Merge pull request #2085 from tannewt/epd

Rework display refresh, add M4SK and add ePaper support

17 files changed, 1273 insertions, 460 deletions

diff --git a/shared-module/displayio/ColorConverter.c b/shared-module/displayio/ColorConverter.c
index 6b9bd5840..940aaa1c6 100644
--- a/shared-module/displayio/ColorConverter.c
+++ b/shared-module/displayio/ColorConverter.c
@@ -26,6 +26,8 @@
 
 #include "shared-bindings/displayio/ColorConverter.h"
 
+#include "py/misc.h"
+
 void common_hal_displayio_colorconverter_construct(displayio_colorconverter_t* self) {
 }
 
@@ -45,10 +47,71 @@ uint8_t displayio_colorconverter_compute_luma(uint32_t color_rgb888) {
     return (r8 * 19) / 255 + (g8 * 182) / 255 + (b8 + 54) / 255;
 }
 
+uint8_t displayio_colorconverter_compute_chroma(uint32_t color_rgb888) {
+    uint32_t r8 = (color_rgb888 >> 16);
+    uint32_t g8 = (color_rgb888 >> 8) & 0xff;
+    uint32_t b8 = color_rgb888 & 0xff;
+    uint8_t max = MAX(r8, MAX(g8, b8));
+    uint8_t min = MIN(r8, MIN(g8, b8));
+    return max - min;
+}
+
+uint8_t displayio_colorconverter_compute_hue(uint32_t color_rgb888) {
+    uint32_t r8 = (color_rgb888 >> 16);
+    uint32_t g8 = (color_rgb888 >> 8) & 0xff;
+    uint32_t b8 = color_rgb888 & 0xff;
+    uint8_t max = MAX(r8, MAX(g8, b8));
+    uint8_t min = MIN(r8, MIN(g8, b8));
+    uint8_t c = max - min;
+    if (c == 0) {
+        return 0;
+    }
+
+    int32_t hue = 0;
+    if (max == r8) {
+        hue = (((int32_t) (g8 - b8) * 40) / c) % 240;
+    } else if (max == g8) {
+        hue = (((int32_t) (b8 - r8) + (2 * c)) * 40) / c;
+    } else if (max == b8) {
+        hue = (((int32_t) (r8 - g8) + (4 * c)) * 40) / c;
+    }
+    if (hue < 0) {
+        hue += 240;
+    }
+
+    return hue;
+}
+
+void displayio_colorconverter_compute_tricolor(const _displayio_colorspace_t* colorspace, uint8_t pixel_hue, uint8_t pixel_luma, uint32_t*  color) {
+
+    int16_t hue_diff = colorspace->tricolor_hue - pixel_hue;
+    if ((-10 <= hue_diff && hue_diff <= 10) || hue_diff <= -220 || hue_diff >= 220) {
+        if (colorspace->grayscale) {
+            *color = 0;
+        } else {
+            *color = 1;
+        }
+    } else if (!colorspace->grayscale) {
+        *color = 0;
+    }
+}
+
 bool displayio_colorconverter_convert(displayio_colorconverter_t *self, const _displayio_colorspace_t* colorspace, uint32_t input_color, uint32_t* output_color) {
     if (colorspace->depth == 16) {
         *output_color = displayio_colorconverter_compute_rgb565(input_color);
         return true;
+    } else if (colorspace->tricolor) {
+        uint8_t luma = displayio_colorconverter_compute_luma(input_color);
+        *output_color = luma >> (8 - colorspace->depth);
+        if (displayio_colorconverter_compute_chroma(input_color) <= 16) {
+            if (!colorspace->grayscale) {
+                *output_color = 0;
+            }
+            return true;
+        }
+        uint8_t pixel_hue = displayio_colorconverter_compute_hue(input_color);
+        displayio_colorconverter_compute_tricolor(colorspace, pixel_hue, luma, output_color);
+        return true;
     } else if (colorspace->grayscale && colorspace->depth <= 8) {
         uint8_t luma = displayio_colorconverter_compute_luma(input_color);
         *output_color = luma >> (8 - colorspace->depth);
diff --git a/shared-module/displayio/ColorConverter.h b/shared-module/displayio/ColorConverter.h
index c48b98e6d..c79e6a2f7 100644
--- a/shared-module/displayio/ColorConverter.h
+++ b/shared-module/displayio/ColorConverter.h
@@ -42,5 +42,8 @@ void displayio_colorconverter_finish_refresh(displayio_colorconverter_t *self);
 bool displayio_colorconverter_convert(displayio_colorconverter_t *self, const _displayio_colorspace_t* colorspace, uint32_t input_color, uint32_t* output_color);
 uint16_t displayio_colorconverter_compute_rgb565(uint32_t color_rgb888);
 uint8_t displayio_colorconverter_compute_luma(uint32_t color_rgb888);
+uint8_t displayio_colorconverter_compute_chroma(uint32_t color_rgb888);
+uint8_t displayio_colorconverter_compute_hue(uint32_t color_rgb888);
+void displayio_colorconverter_compute_tricolor(const _displayio_colorspace_t* colorspace, uint8_t pixel_hue, uint8_t pixel_luma, uint32_t*  color);
 
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_COLORCONVERTER_H
diff --git a/shared-module/displayio/Display.c b/shared-module/displayio/Display.c
index d11813b8c..f210a80c3 100644
--- a/shared-module/displayio/Display.c
+++ b/shared-module/displayio/Display.c
@@ -33,75 +33,64 @@
 #include "shared-bindings/microcontroller/Pin.h"
 #include "shared-bindings/time/__init__.h"
 #include "shared-module/displayio/__init__.h"
+#include "shared-module/displayio/display_core.h"
 #include "supervisor/shared/display.h"
+#include "supervisor/usb.h"
 
 #include <stdint.h>
 #include <string.h>
 
 #include "tick.h"
 
-#define DELAY 0x80
-
 void common_hal_displayio_display_construct(displayio_display_obj_t* self,
-        mp_obj_t bus, uint16_t width, uint16_t height, int16_t colstart, int16_t rowstart, uint16_t rotation,
-        uint16_t color_depth, bool grayscale, bool pixels_in_byte_share_row, uint8_t bytes_per_cell, bool reverse_pixels_in_byte,
-        uint8_t set_column_command, uint8_t set_row_command,
-        uint8_t write_ram_command, uint8_t set_vertical_scroll, uint8_t* init_sequence, uint16_t init_sequence_len,
-        const mcu_pin_obj_t* backlight_pin, uint16_t brightness_command, mp_float_t brightness, bool auto_brightness,
-        bool single_byte_bounds, bool data_as_commands) {
-    self->colorspace.depth = color_depth;
-    self->colorspace.grayscale = grayscale;
-    self->colorspace.pixels_in_byte_share_row = pixels_in_byte_share_row;
-    self->colorspace.bytes_per_cell = bytes_per_cell;
-    self->colorspace.reverse_pixels_in_byte = reverse_pixels_in_byte;
+        mp_obj_t bus, uint16_t width, uint16_t height, int16_t colstart, int16_t rowstart,
+        uint16_t rotation, uint16_t color_depth, bool grayscale, bool pixels_in_byte_share_row,
+        uint8_t bytes_per_cell, bool reverse_pixels_in_byte, uint8_t set_column_command,
+        uint8_t set_row_command, uint8_t write_ram_command, uint8_t set_vertical_scroll,
+        uint8_t* init_sequence, uint16_t init_sequence_len, const mcu_pin_obj_t* backlight_pin,
+        uint16_t brightness_command, mp_float_t brightness, bool auto_brightness,
+        bool single_byte_bounds, bool data_as_commands, bool auto_refresh, uint16_t native_frames_per_second) {
+    uint16_t ram_width = 0x100;
+    uint16_t ram_height = 0x100;
+    if (single_byte_bounds) {
+        ram_width = 0xff;
+        ram_height = 0xff;
+    }
+    displayio_display_core_construct(&self->core, bus, width, height, ram_width, ram_height, colstart, rowstart, rotation,
+        color_depth, grayscale, pixels_in_byte_share_row, bytes_per_cell, reverse_pixels_in_byte);
+
     self->set_column_command = set_column_command;
     self->set_row_command = set_row_command;
     self->write_ram_command = write_ram_command;
-    self->refresh = false;
-    self->current_group = NULL;
-    self->colstart = colstart;
-    self->rowstart = rowstart;
     self->brightness_command = brightness_command;
     self->auto_brightness = auto_brightness;
+    self->auto_refresh = auto_refresh;
+    self->first_manual_refresh = !auto_refresh;
     self->data_as_commands = data_as_commands;
-    self->single_byte_bounds = single_byte_bounds;
-
-    if (MP_OBJ_IS_TYPE(bus, &displayio_parallelbus_type)) {
-        self->begin_transaction = common_hal_displayio_parallelbus_begin_transaction;
-        self->send = common_hal_displayio_parallelbus_send;
-        self->end_transaction = common_hal_displayio_parallelbus_end_transaction;
-    } else if (MP_OBJ_IS_TYPE(bus, &displayio_fourwire_type)) {
-        self->begin_transaction = common_hal_displayio_fourwire_begin_transaction;
-        self->send = common_hal_displayio_fourwire_send;
-        self->end_transaction = common_hal_displayio_fourwire_end_transaction;
-    } else if (MP_OBJ_IS_TYPE(bus, &displayio_i2cdisplay_type)) {
-        self->begin_transaction = common_hal_displayio_i2cdisplay_begin_transaction;
-        self->send = common_hal_displayio_i2cdisplay_send;
-        self->end_transaction = common_hal_displayio_i2cdisplay_end_transaction;
-    } else {
-        mp_raise_ValueError(translate("Unsupported display bus type"));
-    }
-    self->bus = bus;
+
+    self->native_frames_per_second = native_frames_per_second;
+    self->native_ms_per_frame = 1000 / native_frames_per_second;
 
     uint32_t i = 0;
-    while (!self->begin_transaction(self->bus)) {
-        RUN_BACKGROUND_TASKS;
-    }
     while (i < init_sequence_len) {
         uint8_t *cmd = init_sequence + i;
         uint8_t data_size = *(cmd + 1);
         bool delay = (data_size & DELAY) != 0;
         data_size &= ~DELAY;
         uint8_t *data = cmd + 2;
+        while (!displayio_display_core_begin_transaction(&self->core)) {
+            RUN_BACKGROUND_TASKS;
+        }
         if (self->data_as_commands) {
             uint8_t full_command[data_size + 1];
             full_command[0] = cmd[0];
             memcpy(full_command + 1, data, data_size);
-            self->send(self->bus, true, full_command, data_size + 1);
+            self->core.send(self->core.bus, DISPLAY_COMMAND, CHIP_SELECT_TOGGLE_EVERY_BYTE, full_command, data_size + 1);
         } else {
-            self->send(self->bus, true, cmd, 1);
-            self->send(self->bus, false, data, data_size);
+            self->core.send(self->core.bus, DISPLAY_COMMAND, CHIP_SELECT_TOGGLE_EVERY_BYTE, cmd, 1);
+            self->core.send(self->core.bus, DISPLAY_DATA, CHIP_SELECT_UNTOUCHED, data, data_size);
         }
+        self->core.end_transaction(self->core.bus);
         uint16_t delay_length_ms = 10;
         if (delay) {
             data_size++;
@@ -113,33 +102,9 @@ void common_hal_displayio_display_construct(displayio_display_obj_t* self,
         common_hal_time_delay_ms(delay_length_ms);
         i += 2 + data_size;
     }
-    self->end_transaction(self->bus);
 
     supervisor_start_terminal(width, height);
 
-    self->width = width;
-    self->height = height;
-    self->rotation = rotation % 360;
-    self->transform.x = 0;
-    self->transform.y = 0;
-    self->transform.scale = 1;
-    self->transform.mirror_x = false;
-    self->transform.mirror_y = false;
-    self->transform.transpose_xy = false;
-    if (rotation == 0 || rotation == 180) {
-        if (rotation == 180) {
-            self->transform.mirror_x = true;
-            self->transform.mirror_y = true;
-        }
-    } else {
-        self->transform.transpose_xy = true;
-        if (rotation == 270) {
-            self->transform.mirror_y = true;
-        } else {
-            self->transform.mirror_x = true;
-        }
-    }
-
     // Always set the backlight type in case we're reusing memory.
     self->backlight_inout.base.type = &mp_type_NoneType;
     if (backlight_pin != NULL && common_hal_mcu_pin_is_free(backlight_pin)) {
@@ -160,105 +125,25 @@ void common_hal_displayio_display_construct(displayio_display_obj_t* self,
         self->current_brightness = -1.0;
     }
 
-    self->area.x1 = 0;
-    self->area.y1 = 0;
-    self->area.next = NULL;
-
-    self->transform.dx = 1;
-    self->transform.dy = 1;
-    if (self->transform.transpose_xy) {
-        self->area.x2 = height;
-        self->area.y2 = width;
-        if (self->transform.mirror_x) {
-            self->transform.x = height;
-            self->transform.dx = -1;
-        }
-        if (self->transform.mirror_y) {
-            self->transform.y = width;
-            self->transform.dy = -1;
-        }
-    } else {
-        self->area.x2 = width;
-        self->area.y2 = height;
-        if (self->transform.mirror_x) {
-            self->transform.x = width;
-            self->transform.dx = -1;
-        }
-        if (self->transform.mirror_y) {
-            self->transform.y = height;
-            self->transform.dy = -1;
-        }
-    }
-
     // Set the group after initialization otherwise we may send pixels while we delay in
     // initialization.
     common_hal_displayio_display_show(self, &circuitpython_splash);
 }
 
 bool common_hal_displayio_display_show(displayio_display_obj_t* self, displayio_group_t* root_group) {
-    if (root_group == NULL) {
-        if (!circuitpython_splash.in_group) {
-            root_group = &circuitpython_splash;
-        } else if (self->current_group == &circuitpython_splash) {
-            return false;
-        }
-    }
-    if (root_group == self->current_group) {
-        return true;
-    }
-    if (root_group != NULL && root_group->in_group) {
-        return false;
-    }
-    if (self->current_group != NULL) {
-        self->current_group->in_group = false;
-    }
-
-    if (root_group != NULL) {
-        displayio_group_update_transform(root_group, &self->transform);
-        root_group->in_group = true;
-    }
-    self->current_group = root_group;
-    self->full_refresh = true;
-    common_hal_displayio_display_refresh_soon(self);
-    return true;
-}
-
-void common_hal_displayio_display_refresh_soon(displayio_display_obj_t* self) {
-    self->refresh = true;
-}
-
-const displayio_area_t* displayio_display_get_refresh_areas(displayio_display_obj_t *self) {
-    if (self->full_refresh) {
-        self->area.next = NULL;
-        return &self->area;
-    } else {
-        return displayio_group_get_refresh_areas(self->current_group, NULL);
-    }
-}
-
-int32_t common_hal_displayio_display_wait_for_frame(displayio_display_obj_t* self) {
-    uint64_t last_refresh = self->last_refresh;
-    // Don't try to refresh if we got an exception.
-    while (last_refresh == self->last_refresh && MP_STATE_VM(mp_pending_exception) == NULL) {
-        RUN_BACKGROUND_TASKS;
-    }
-    return 0;
-}
-
-bool common_hal_displayio_display_get_auto_brightness(displayio_display_obj_t* self) {
-    return self->auto_brightness;
+    return displayio_display_core_show(&self->core, root_group);
 }
 
 uint16_t common_hal_displayio_display_get_width(displayio_display_obj_t* self){
-    return self->width;
+    return displayio_display_core_get_width(&self->core);
 }
 
 uint16_t common_hal_displayio_display_get_height(displayio_display_obj_t* self){
-    return self->height;
+    return displayio_display_core_get_height(&self->core);
 }
 
-uint16_t common_hal_displayio_display_get_rotation(displayio_display_obj_t* self){
-    return self->rotation;
+bool common_hal_displayio_display_get_auto_brightness(displayio_display_obj_t* self) {
+    return self->auto_brightness;
 }
 
 void common_hal_displayio_display_set_auto_brightness(displayio_display_obj_t* self, bool auto_brightness) {
@@ -279,18 +164,18 @@ bool common_hal_displayio_display_set_brightness(displayio_display_obj_t* self,
         common_hal_digitalio_digitalinout_set_value(&self->backlight_inout, brightness > 0.99);
         ok = true;
     } else if (self->brightness_command != NO_BRIGHTNESS_COMMAND) {
-        ok = self->begin_transaction(self->bus);
+        ok = displayio_display_core_begin_transaction(&self->core);
         if (ok) {
             if (self->data_as_commands) {
                 uint8_t set_brightness[2] = {self->brightness_command, (uint8_t) (0xff * brightness)};
-                self->send(self->bus, true, set_brightness, 2);
+                self->core.send(self->core.bus, DISPLAY_COMMAND, CHIP_SELECT_TOGGLE_EVERY_BYTE, set_brightness, 2);
             } else {
                 uint8_t command = self->brightness_command;
                 uint8_t hex_brightness = 0xff * brightness;
-                self->send(self->bus, true, &command, 1);
-                self->send(self->bus, false, &hex_brightness, 1);
+                self->core.send(self->core.bus, DISPLAY_COMMAND, CHIP_SELECT_TOGGLE_EVERY_BYTE, &command, 1);
+                self->core.send(self->core.bus, DISPLAY_DATA, CHIP_SELECT_UNTOUCHED, &hex_brightness, 1);
             }
-            self->end_transaction(self->bus);
+            displayio_display_core_end_transaction(&self->core);
         }
 
     }
@@ -301,102 +186,165 @@ bool common_hal_displayio_display_set_brightness(displayio_display_obj_t* self,
     return ok;
 }
 
-bool displayio_display_begin_transaction(displayio_display_obj_t* self) {
-    return self->begin_transaction(self->bus);
+mp_obj_t common_hal_displayio_display_get_bus(displayio_display_obj_t* self) {
+    return self->core.bus;
 }
 
-void displayio_display_end_transaction(displayio_display_obj_t* self) {
-    self->end_transaction(self->bus);
+STATIC const displayio_area_t* _get_refresh_areas(displayio_display_obj_t *self) {
+    if (self->core.full_refresh) {
+        self->core.area.next = NULL;
+        return &self->core.area;
+    } else if (self->core.current_group != NULL) {
+        return displayio_group_get_refresh_areas(self->core.current_group, NULL);
+    }
+    return NULL;
 }
 
-void displayio_display_set_region_to_update(displayio_display_obj_t* self, displayio_area_t* area) {
-    uint16_t x1 = area->x1;
-    uint16_t x2 = area->x2;
-    uint16_t y1 = area->y1;
-    uint16_t y2 = area->y2;
-    // Collapse down the dimension where multiple pixels are in a byte.
-    if (self->colorspace.depth < 8) {
-        uint8_t pixels_per_byte = 8 / self->colorspace.depth;
-        if (self->colorspace.pixels_in_byte_share_row) {
-            x1 /= pixels_per_byte * self->colorspace.bytes_per_cell;
-            x2 /= pixels_per_byte * self->colorspace.bytes_per_cell;
-        } else {
-            y1 /= pixels_per_byte * self->colorspace.bytes_per_cell;
-            y2 /= pixels_per_byte * self->colorspace.bytes_per_cell;
-        }
+STATIC void _send_pixels(displayio_display_obj_t* self, uint8_t* pixels, uint32_t length) {
+    if (!self->data_as_commands) {
+        self->core.send(self->core.bus, DISPLAY_COMMAND, CHIP_SELECT_TOGGLE_EVERY_BYTE, &self->write_ram_command, 1);
     }
+    self->core.send(self->core.bus, DISPLAY_DATA, CHIP_SELECT_UNTOUCHED, pixels, length);
+}
 
-    // Set column.
-    uint8_t data[5];
-    data[0] = self->set_column_command;
-    uint8_t data_length = 1;
-    if (!self->data_as_commands) {
-        self->send(self->bus, true, data, 1);
-        data_length = 0;
+STATIC bool _refresh_area(displayio_display_obj_t* self, const displayio_area_t* area) {
+    uint16_t buffer_size = 128; // In uint32_ts
+
+    displayio_area_t clipped;
+    // Clip the area to the display by overlapping the areas. If there is no overlap then we're done.
+    if (!displayio_display_core_clip_area(&self->core, area, &clipped)) {
+        return true;
     }
-    if (self->single_byte_bounds) {
-        data[data_length++] = x1 + self->colstart;
-        data[data_length++] = x2 - 1 + self->colstart;
-    } else {
-        x1 += self->colstart;
-        x2 += self->colstart - 1;
-        data[data_length++] = x1 >> 8;
-        data[data_length++] = x1 & 0xff;
-        data[data_length++] = x2 >> 8;
-        data[data_length++] = x2 & 0xff;
+    uint16_t subrectangles = 1;
+    uint16_t rows_per_buffer = displayio_area_height(&clipped);
+    uint8_t pixels_per_word = (sizeof(uint32_t) * 8) / self->core.colorspace.depth;
+    uint16_t pixels_per_buffer = displayio_area_size(&clipped);
+    if (displayio_area_size(&clipped) > buffer_size * pixels_per_word) {
+        rows_per_buffer = buffer_size * pixels_per_word / displayio_area_width(&clipped);
+        if (rows_per_buffer == 0) {
+            rows_per_buffer = 1;
+        }
+        // If pixels are packed by column then ensure rows_per_buffer is on a byte boundary.
+        if (self->core.colorspace.depth < 8 && !self->core.colorspace.pixels_in_byte_share_row) {
+            uint8_t pixels_per_byte = 8 / self->core.colorspace.depth;
+            if (rows_per_buffer % pixels_per_byte != 0) {
+                rows_per_buffer -= rows_per_buffer % pixels_per_byte;
+            }
+        }
+        subrectangles = displayio_area_height(&clipped) / rows_per_buffer;
+        if (displayio_area_height(&clipped) % rows_per_buffer != 0) {
+            subrectangles++;
+        }
+        pixels_per_buffer = rows_per_buffer * displayio_area_width(&clipped);
+        buffer_size = pixels_per_buffer / pixels_per_word;
+        if (pixels_per_buffer % pixels_per_word) {
+            buffer_size += 1;
+        }
     }
-    self->send(self->bus, self->data_as_commands, data, data_length);
 
-    // Set row.
-    data[0] = self->set_row_command;
-    data_length = 1;
-    if (!self->data_as_commands) {
-        self->send(self->bus, true, data, 1);
-        data_length = 0;
+    // Allocated and shared as a uint32_t array so the compiler knows the
+    // alignment everywhere.
+    uint32_t buffer[buffer_size];
+    uint32_t mask_length = (pixels_per_buffer / 32) + 1;
+    uint32_t mask[mask_length];
+    uint16_t remaining_rows = displayio_area_height(&clipped);
+
+    for (uint16_t j = 0; j < subrectangles; j++) {
+        displayio_area_t subrectangle = {
+            .x1 = clipped.x1,
+            .y1 = clipped.y1 + rows_per_buffer * j,
+            .x2 = clipped.x2,
+            .y2 = clipped.y1 + rows_per_buffer * (j + 1)
+        };
+        if (remaining_rows < rows_per_buffer) {
+            subrectangle.y2 = subrectangle.y1 + remaining_rows;
+        }
+        remaining_rows -= rows_per_buffer;
+
+        displayio_display_core_set_region_to_update(&self->core, self->set_column_command, self->set_row_command, NO_COMMAND, NO_COMMAND, self->data_as_commands, false, &subrectangle);
+
+        uint16_t subrectangle_size_bytes;
+        if (self->core.colorspace.depth >= 8) {
+            subrectangle_size_bytes = displayio_area_size(&subrectangle) * (self->core.colorspace.depth / 8);
+        } else {
+            subrectangle_size_bytes = displayio_area_size(&subrectangle) / (8 / self->core.colorspace.depth);
+        }
+
+        memset(mask, 0, mask_length * sizeof(mask[0]));
+        memset(buffer, 0, buffer_size * sizeof(buffer[0]));
+
+        displayio_display_core_fill_area(&self->core, &subrectangle, mask, buffer);
+
+        // Can't acquire display bus; skip the rest of the data.
+        if (!displayio_display_core_bus_free(&self->core)) {
+            return false;
+        }
+
+        displayio_display_core_begin_transaction(&self->core);
+        _send_pixels(self, (uint8_t*) buffer, subrectangle_size_bytes);
+        displayio_display_core_end_transaction(&self->core);
+
+        // TODO(tannewt): Make refresh displays faster so we don't starve other
+        // background tasks.
+        usb_background();
     }
-    if (self->single_byte_bounds) {
-        data[data_length++] = y1 + self->rowstart;
-        data[data_length++] = y2 - 1 + self->rowstart;
-    } else {
-        y1 += self->rowstart;
-        y2 += self->rowstart - 1;
-        data[data_length++] = y1 >> 8;
-        data[data_length++] = y1 & 0xff;
-        data[data_length++] = y2 >> 8;
-        data[data_length++] = y2 & 0xff;
+    return true;
+}
+
+STATIC void _refresh_display(displayio_display_obj_t* self) {
+    if (!displayio_display_core_bus_free(&self->core)) {
+        // Can't acquire display bus; skip updating this display. Try next display.
+        return;
     }
-    self->send(self->bus, self->data_as_commands, data, data_length);
+    displayio_display_core_start_refresh(&self->core);
+    const displayio_area_t* current_area = _get_refresh_areas(self);
+    while (current_area != NULL) {
+        _refresh_area(self, current_area);
+        current_area = current_area->next;
+    }
+    displayio_display_core_finish_refresh(&self->core);
 }
 
-void displayio_display_start_refresh(displayio_display_obj_t* self) {
-    self->last_refresh = ticks_ms;
+uint16_t common_hal_displayio_display_get_rotation(displayio_display_obj_t* self){
+    return self->core.rotation;
 }
 
-bool displayio_display_frame_queued(displayio_display_obj_t* self) {
-    if (self->current_group == NULL) {
-        return false;
+bool common_hal_displayio_display_refresh(displayio_display_obj_t* self, uint32_t target_ms_per_frame, uint32_t maximum_ms_per_real_frame) {
+    if (!self->auto_refresh && !self->first_manual_refresh) {
+        uint64_t current_time = ticks_ms;
+        uint32_t current_ms_since_real_refresh = current_time - self->core.last_refresh;
+        // Test to see if the real frame time is below our minimum.
+        if (current_ms_since_real_refresh > maximum_ms_per_real_frame) {
+            mp_raise_RuntimeError(translate("Below minimum frame rate"));
+        }
+        uint32_t current_ms_since_last_call = current_time - self->last_refresh_call;
+        self->last_refresh_call = current_time;
+        // Skip the actual refresh to help catch up.
+        if (current_ms_since_last_call > target_ms_per_frame) {
+            return false;
+        }
+        uint32_t remaining_time = target_ms_per_frame - (current_ms_since_real_refresh % target_ms_per_frame);
+        // We're ahead of the game so wait until we align with the frame rate.
+        while (ticks_ms - self->last_refresh_call < remaining_time) {
+            RUN_BACKGROUND_TASKS;
+        }
     }
-    // Refresh at ~60 fps.
-    return (ticks_ms - self->last_refresh) > 16;
+    self->first_manual_refresh = false;
+    _refresh_display(self);
+    return true;
 }
 
-void displayio_display_finish_refresh(displayio_display_obj_t* self) {
-    if (self->current_group != NULL) {
-        displayio_group_finish_refresh(self->current_group);
-    }
-    self->refresh = false;
-    self->full_refresh = false;
-    self->last_refresh = ticks_ms;
+bool common_hal_displayio_display_get_auto_refresh(displayio_display_obj_t* self) {
+    return self->auto_refresh;
 }
 
-void displayio_display_send_pixels(displayio_display_obj_t* self, uint8_t* pixels, uint32_t length) {
-    if (!self->data_as_commands) {
-        self->send(self->bus, true, &self->write_ram_command, 1);
-    }
-    self->send(self->bus, false, pixels, length);
+void common_hal_displayio_display_set_auto_refresh(displayio_display_obj_t* self,
+                                                   bool auto_refresh) {
+    self->first_manual_refresh = !auto_refresh;
+    self->auto_refresh = auto_refresh;
 }
 
-void displayio_display_update_backlight(displayio_display_obj_t* self) {
+STATIC void _update_backlight(displayio_display_obj_t* self) {
     if (!self->auto_brightness || self->updating_backlight) {
         return;
     }
@@ -410,11 +358,16 @@ void displayio_display_update_backlight(displayio_display_obj_t* self) {
     self->last_backlight_refresh = ticks_ms;
 }
 
-void release_display(displayio_display_obj_t* self) {
-    if (self->current_group != NULL) {
-        self->current_group->in_group = false;
+void displayio_display_background(displayio_display_obj_t* self) {
+    _update_backlight(self);
+
+    if (self->auto_refresh && (ticks_ms - self->core.last_refresh) > self->native_ms_per_frame) {
+        _refresh_display(self);
     }
+}
 
+void release_display(displayio_display_obj_t* self) {
+    release_display_core(&self->core);
     if (self->backlight_pwm.base.type == &pulseio_pwmout_type) {
         common_hal_pulseio_pwmout_reset_ok(&self->backlight_pwm);
         common_hal_pulseio_pwmout_deinit(&self->backlight_pwm);
@@ -423,34 +376,12 @@ void release_display(displayio_display_obj_t* self) {
     }
 }
 
-bool displayio_display_fill_area(displayio_display_obj_t *self, displayio_area_t* area, uint32_t* mask, uint32_t *buffer) {
-    return displayio_group_fill_area(self->current_group, &self->colorspace, area, mask, buffer);
+void reset_display(displayio_display_obj_t* self) {
+    self->auto_refresh = true;
+    self->auto_brightness = true;
+    common_hal_displayio_display_show(self, NULL);
 }
 
-bool displayio_display_clip_area(displayio_display_obj_t *self, const displayio_area_t* area, displayio_area_t* clipped) {
-    bool overlaps = displayio_area_compute_overlap(&self->area, area, clipped);
-    if (!overlaps) {
-        return false;
-    }
-    // Expand the area if we have multiple pixels per byte and we need to byte
-    // align the bounds.
-    if (self->colorspace.depth < 8) {
-        uint8_t pixels_per_byte = 8 / self->colorspace.depth * self->colorspace.bytes_per_cell;
-        if (self->colorspace.pixels_in_byte_share_row) {
-            if (clipped->x1 % pixels_per_byte != 0) {
-                clipped->x1 -= clipped->x1 % pixels_per_byte;
-            }
-            if (clipped->x2 % pixels_per_byte != 0) {
-                clipped->x2 += pixels_per_byte - clipped->x2 % pixels_per_byte;
-            }
-        } else {
-            if (clipped->y1 % pixels_per_byte != 0) {
-                clipped->y1 -= clipped->y1 % pixels_per_byte;
-            }
-            if (clipped->y2 % pixels_per_byte != 0) {
-                clipped->y2 += pixels_per_byte - clipped->y2 % pixels_per_byte;
-            }
-        }
-    }
-    return true;
+void displayio_display_collect_ptrs(displayio_display_obj_t* self) {
+    displayio_display_core_collect_ptrs(&self->core);
 }
diff --git a/shared-module/displayio/Display.h b/shared-module/displayio/Display.h
index 74ae175b1..e5fe0a708 100644
--- a/shared-module/displayio/Display.h
+++ b/shared-module/displayio/Display.h
@@ -32,50 +32,35 @@
 #include "shared-bindings/pulseio/PWMOut.h"
 
 #include "shared-module/displayio/area.h"
-
-typedef bool (*display_bus_begin_transaction)(mp_obj_t bus);
-typedef void (*display_bus_send)(mp_obj_t bus, bool command, uint8_t *data, uint32_t data_length);
-typedef void (*display_bus_end_transaction)(mp_obj_t bus);
+#include "shared-module/displayio/display_core.h"
 
 typedef struct {
     mp_obj_base_t base;
-    mp_obj_t bus;
-    displayio_group_t *current_group;
-    uint64_t last_refresh;
-    display_bus_begin_transaction begin_transaction;
-    display_bus_send send;
-    display_bus_end_transaction end_transaction;
+    displayio_display_core_t core;
     union {
         digitalio_digitalinout_obj_t backlight_inout;
         pulseio_pwmout_obj_t backlight_pwm;
     };
     uint64_t last_backlight_refresh;
-    displayio_buffer_transform_t transform;
-    displayio_area_t area;
+    uint64_t last_refresh_call;
     mp_float_t current_brightness;
-    uint16_t width;
-    uint16_t height;
-    uint16_t rotation;
-    _displayio_colorspace_t colorspace;
-    int16_t colstart;
-    int16_t rowstart;
     uint16_t brightness_command;
+    uint16_t native_frames_per_second;
+    uint16_t native_ms_per_frame;
     uint8_t set_column_command;
     uint8_t set_row_command;
     uint8_t write_ram_command;
-    bool refresh;
-    bool single_byte_bounds;
+    bool auto_refresh;
+    bool first_manual_refresh;
     bool data_as_commands;
     bool auto_brightness;
     bool updating_backlight;
-    bool full_refresh; // New group means we need to refresh the whole display.
 } displayio_display_obj_t;
 
-void displayio_display_start_refresh(displayio_display_obj_t* self);
-const displayio_area_t* displayio_display_get_refresh_areas(displayio_display_obj_t *self);
-bool displayio_display_fill_area(displayio_display_obj_t *self, displayio_area_t* area, uint32_t* mask, uint32_t *buffer);
-void displayio_display_update_backlight(displayio_display_obj_t* self);
-bool displayio_display_clip_area(displayio_display_obj_t *self, const displayio_area_t* area, displayio_area_t* clipped);
+void displayio_display_background(displayio_display_obj_t* self);
 void release_display(displayio_display_obj_t* self);
+void reset_display(displayio_display_obj_t* self);
+
+void displayio_display_collect_ptrs(displayio_display_obj_t* self);
 
 #endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_DISPLAY_H
diff --git a/shared-module/displayio/EPaperDisplay.c b/shared-module/displayio/EPaperDisplay.c
new file mode 100644
index 000000000..efbd9f3dd
--- /dev/null
+++ b/shared-module/displayio/EPaperDisplay.c
@@ -0,0 +1,385 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "shared-bindings/displayio/EPaperDisplay.h"
+
+#include "py/runtime.h"
+#include "shared-bindings/displayio/ColorConverter.h"
+#include "shared-bindings/displayio/FourWire.h"
+#include "shared-bindings/displayio/I2CDisplay.h"
+#include "shared-bindings/displayio/ParallelBus.h"
+#include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/time/__init__.h"
+#include "shared-module/displayio/__init__.h"
+#include "supervisor/shared/display.h"
+#include "supervisor/usb.h"
+
+#include <stdint.h>
+#include <string.h>
+
+#include "tick.h"
+
+void common_hal_displayio_epaperdisplay_construct(displayio_epaperdisplay_obj_t* self,
+        mp_obj_t bus, uint8_t* start_sequence, uint16_t start_sequence_len, uint8_t* stop_sequence, uint16_t stop_sequence_len,
+        uint16_t width, uint16_t height, uint16_t ram_width, uint16_t ram_height,
+        int16_t colstart, int16_t rowstart, uint16_t rotation,
+        uint16_t set_column_window_command, uint16_t set_row_window_command,
+        uint16_t set_current_column_command, uint16_t set_current_row_command,
+        uint16_t write_black_ram_command, bool black_bits_inverted, uint16_t write_color_ram_command, bool color_bits_inverted, uint32_t highlight_color, uint16_t refresh_display_command, mp_float_t refresh_time,
+        const mcu_pin_obj_t* busy_pin, bool busy_state, mp_float_t seconds_per_frame, bool chip_select) {
+    if (highlight_color != 0x000000) {
+        self->core.colorspace.tricolor = true;
+        self->core.colorspace.tricolor_hue = displayio_colorconverter_compute_hue(highlight_color);
+        self->core.colorspace.tricolor_luma = displayio_colorconverter_compute_luma(highlight_color);
+    }
+
+    displayio_display_core_construct(&self->core, bus, width, height, ram_width, ram_height, colstart, rowstart, rotation, 1, true, true, 1, true);
+
+    self->set_column_window_command = set_column_window_command;
+    self->set_row_window_command = set_row_window_command;
+    self->set_current_column_command = set_current_column_command;
+    self->set_current_row_command = set_current_row_command;
+    self->write_black_ram_command = write_black_ram_command;
+    self->black_bits_inverted = black_bits_inverted;
+    self->write_color_ram_command = write_color_ram_command;
+    self->color_bits_inverted = color_bits_inverted;
+    self->refresh_display_command = refresh_display_command;
+    self->refresh_time = refresh_time * 1000;
+    self->busy_state = busy_state;
+    self->refreshing = false;
+    self->milliseconds_per_frame = seconds_per_frame * 1000;
+    self->chip_select = chip_select ? CHIP_SELECT_TOGGLE_EVERY_BYTE : CHIP_SELECT_UNTOUCHED;
+
+    self->start_sequence = start_sequence;
+    self->start_sequence_len = start_sequence_len;
+    self->stop_sequence = stop_sequence;
+    self->stop_sequence_len = stop_sequence_len;
+
+    self->busy.base.type = &mp_type_NoneType;
+    if (busy_pin != NULL) {
+        self->busy.base.type = &digitalio_digitalinout_type;
+        common_hal_digitalio_digitalinout_construct(&self->busy, busy_pin);
+        never_reset_pin_number(busy_pin->number);
+    }
+
+    // Clear the color memory if it isn't in use.
+    if (highlight_color == 0x00 && write_color_ram_command != NO_COMMAND) {
+        // TODO: Clear
+    }
+
+    supervisor_start_terminal(width, height);
+
+    // Set the group after initialization otherwise we may send pixels while we delay in
+    // initialization.
+    common_hal_displayio_epaperdisplay_show(self, &circuitpython_splash);
+}
+
+bool common_hal_displayio_epaperdisplay_show(displayio_epaperdisplay_obj_t* self, displayio_group_t* root_group) {
+    return displayio_display_core_show(&self->core, root_group);
+}
+
+const displayio_area_t* displayio_epaperdisplay_get_refresh_areas(displayio_epaperdisplay_obj_t *self) {
+    if (self->core.full_refresh) {
+        self->core.area.next = NULL;
+        return &self->core.area;
+    }
+    const displayio_area_t* first_area = NULL;
+    if (self->core.current_group != NULL) {
+        first_area = displayio_group_get_refresh_areas(self->core.current_group, NULL);
+    }
+    if (first_area != NULL && self->set_row_window_command == NO_COMMAND) {
+        self->core.area.next = NULL;
+        return &self->core.area;
+    }
+    return first_area;
+}
+
+uint16_t common_hal_displayio_epaperdisplay_get_width(displayio_epaperdisplay_obj_t* self){
+    return displayio_display_core_get_width(&self->core);
+}
+
+uint16_t common_hal_displayio_epaperdisplay_get_height(displayio_epaperdisplay_obj_t* self){
+    return displayio_display_core_get_height(&self->core);
+}
+
+STATIC void wait_for_busy(displayio_epaperdisplay_obj_t* self) {
+    if (self->busy.base.type == &mp_type_NoneType) {
+        return;
+    }
+    while (common_hal_digitalio_digitalinout_get_value(&self->busy) == self->busy_state) {
+        RUN_BACKGROUND_TASKS;
+    }
+}
+
+STATIC void send_command_sequence(displayio_epaperdisplay_obj_t* self, bool should_wait_for_busy, uint8_t* sequence, uint32_t sequence_len) {
+    uint32_t i = 0;
+    while (i < sequence_len) {
+        uint8_t *cmd = sequence + i;
+        uint8_t data_size = *(cmd + 1);
+        bool delay = (data_size & DELAY) != 0;
+        data_size &= ~DELAY;
+        uint8_t *data = cmd + 2;
+        displayio_display_core_begin_transaction(&self->core);
+        self->core.send(self->core.bus, DISPLAY_COMMAND, self->chip_select, cmd, 1);
+        self->core.send(self->core.bus, DISPLAY_DATA, self->chip_select, data, data_size);
+        displayio_display_core_end_transaction(&self->core);
+        uint16_t delay_length_ms = 0;
+        if (delay) {
+            data_size++;
+            delay_length_ms = *(cmd + 1 + data_size);
+            if (delay_length_ms == 255) {
+                delay_length_ms = 500;
+            }
+        }
+        common_hal_time_delay_ms(delay_length_ms);
+        if (should_wait_for_busy) {
+            wait_for_busy(self);
+        }
+        i += 2 + data_size;
+    }
+}
+
+void displayio_epaperdisplay_start_refresh(displayio_epaperdisplay_obj_t* self) {
+    // run start sequence
+    self->core.bus_reset(self->core.bus);
+
+    send_command_sequence(self, true, self->start_sequence, self->start_sequence_len);
+    displayio_display_core_start_refresh(&self->core);
+}
+
+uint32_t common_hal_displayio_epaperdisplay_get_time_to_refresh(displayio_epaperdisplay_obj_t* self) {
+    if (self->core.last_refresh == 0) {
+        return 0;
+    }
+    // Refresh at seconds per frame rate.
+    uint32_t elapsed_time = ticks_ms - self->core.last_refresh;
+    if (elapsed_time > self->milliseconds_per_frame) {
+        return 0;
+    }
+    return self->milliseconds_per_frame - elapsed_time;
+}
+
+void displayio_epaperdisplay_finish_refresh(displayio_epaperdisplay_obj_t* self) {
+    // Actually refresh the display now that all pixel RAM has been updated.
+    displayio_display_core_begin_transaction(&self->core);
+    self->core.send(self->core.bus, DISPLAY_COMMAND, self->chip_select, &self->refresh_display_command, 1);
+    displayio_display_core_end_transaction(&self->core);
+    self->refreshing = true;
+
+    displayio_display_core_finish_refresh(&self->core);
+}
+
+mp_obj_t common_hal_displayio_epaperdisplay_get_bus(displayio_epaperdisplay_obj_t* self) {
+    return self->core.bus;
+}
+
+bool displayio_epaperdisplay_refresh_area(displayio_epaperdisplay_obj_t* self, const displayio_area_t* area) {
+    uint16_t buffer_size = 128; // In uint32_ts
+
+    displayio_area_t clipped;
+    // Clip the area to the display by overlapping the areas. If there is no overlap then we're done.
+    if (!displayio_display_core_clip_area(&self->core, area, &clipped)) {
+        return true;
+    }
+    uint16_t subrectangles = 1;
+    uint16_t rows_per_buffer = displayio_area_height(&clipped);
+    uint8_t pixels_per_word = (sizeof(uint32_t) * 8) / self->core.colorspace.depth;
+    uint16_t pixels_per_buffer = displayio_area_size(&clipped);
+    if (displayio_area_size(&clipped) > buffer_size * pixels_per_word) {
+        rows_per_buffer = buffer_size * pixels_per_word / displayio_area_width(&clipped);
+        if (rows_per_buffer == 0) {
+            rows_per_buffer = 1;
+        }
+        subrectangles = displayio_area_height(&clipped) / rows_per_buffer;
+        if (displayio_area_height(&clipped) % rows_per_buffer != 0) {
+            subrectangles++;
+        }
+        pixels_per_buffer = rows_per_buffer * displayio_area_width(&clipped);
+        buffer_size = pixels_per_buffer / pixels_per_word;
+        if (pixels_per_buffer % pixels_per_word) {
+            buffer_size += 1;
+        }
+    }
+
+    // Allocated and shared as a uint32_t array so the compiler knows the
+    // alignment everywhere.
+    uint32_t buffer[buffer_size];
+    volatile uint32_t mask_length = (pixels_per_buffer / 32) + 1;
+    uint32_t mask[mask_length];
+
+    uint8_t passes = 1;
+    if (self->core.colorspace.tricolor) {
+        passes = 2;
+    }
+    for (uint8_t pass = 0; pass < passes; pass++) {
+        uint16_t remaining_rows = displayio_area_height(&clipped);
+
+        if (self->set_row_window_command != NO_COMMAND) {
+            displayio_display_core_set_region_to_update(&self->core, self->set_column_window_command, self->set_row_window_command, self->set_current_column_command, self->set_current_row_command, false, self->chip_select, &clipped);
+        }
+
+        uint8_t write_command = self->write_black_ram_command;
+        if (pass == 1) {
+            write_command = self->write_color_ram_command;
+        }
+        displayio_display_core_begin_transaction(&self->core);
+        self->core.send(self->core.bus, DISPLAY_COMMAND, self->chip_select, &write_command, 1);
+        displayio_display_core_end_transaction(&self->core);
+
+        for (uint16_t j = 0; j < subrectangles; j++) {
+            displayio_area_t subrectangle = {
+                .x1 = clipped.x1,
+                .y1 = clipped.y1 + rows_per_buffer * j,
+                .x2 = clipped.x2,
+                .y2 = clipped.y1 + rows_per_buffer * (j + 1)
+            };
+            if (remaining_rows < rows_per_buffer) {
+                subrectangle.y2 = subrectangle.y1 + remaining_rows;
+            }
+            remaining_rows -= rows_per_buffer;
+
+
+            uint16_t subrectangle_size_bytes = displayio_area_size(&subrectangle) / (8 / self->core.colorspace.depth);
+
+            memset(mask, 0, mask_length * sizeof(mask[0]));
+            memset(buffer, 0, buffer_size * sizeof(buffer[0]));
+
+            self->core.colorspace.grayscale = true;
+            if (pass == 1) {
+                self->core.colorspace.grayscale = false;
+            }
+            displayio_display_core_fill_area(&self->core, &subrectangle, mask, buffer);
+
+            // Invert it all.
+            if ((pass == 1 && self->color_bits_inverted) ||
+                (pass == 0 && self->black_bits_inverted)) {
+                for (uint16_t k = 0; k < buffer_size; k++) {
+                    buffer[k] = ~buffer[k];
+                }
+            }
+
+            if (!displayio_display_core_begin_transaction(&self->core)) {
+                // Can't acquire display bus; skip the rest of the data. Try next display.
+                return false;
+            }
+            self->core.send(self->core.bus, DISPLAY_DATA, self->chip_select, (uint8_t*) buffer, subrectangle_size_bytes);
+            displayio_display_core_end_transaction(&self->core);
+
+            // TODO(tannewt): Make refresh displays faster so we don't starve other
+            // background tasks.
+            usb_background();
+        }
+    }
+
+    return true;
+}
+
+bool common_hal_displayio_epaperdisplay_refresh(displayio_epaperdisplay_obj_t* self) {
+    
+    if (self->refreshing && self->busy.base.type == &digitalio_digitalinout_type) {
+        if (common_hal_digitalio_digitalinout_get_value(&self->busy) != self->busy_state) {
+            self->refreshing = false;
+            // Run stop sequence but don't wait for busy because busy is set when sleeping.
+            send_command_sequence(self, false, self->stop_sequence, self->stop_sequence_len);
+        } else {
+            return false;
+        }
+    }
+    if (self->core.current_group == NULL) {
+        return true;
+    }
+    // Refresh at seconds per frame rate.
+    if (common_hal_displayio_epaperdisplay_get_time_to_refresh(self) > 0) {
+        return false;
+    }
+    if (!displayio_display_core_bus_free(&self->core)) {
+        // Can't acquire display bus; skip updating this display. Try next display.
+        return false;
+    }
+    const displayio_area_t* current_area = displayio_epaperdisplay_get_refresh_areas(self);
+    if (current_area == NULL) {
+        return true;
+    }
+    displayio_epaperdisplay_start_refresh(self);
+    while (current_area != NULL) {
+        displayio_epaperdisplay_refresh_area(self, current_area);
+        current_area = current_area->next;
+    }
+    displayio_epaperdisplay_finish_refresh(self);
+    return true;
+}
+
+void displayio_epaperdisplay_background(displayio_epaperdisplay_obj_t* self) {
+    if (self->refreshing) {
+        bool refresh_done = false;
+        if (self->busy.base.type == &digitalio_digitalinout_type) {
+            bool busy = common_hal_digitalio_digitalinout_get_value(&self->busy);
+            refresh_done = busy != self->busy_state;
+        } else {
+            refresh_done = ticks_ms - self->core.last_refresh > self->refresh_time;
+        }
+        if (refresh_done) {
+            self->refreshing = false;
+            // Run stop sequence but don't wait for busy because busy is set when sleeping.
+            send_command_sequence(self, false, self->stop_sequence, self->stop_sequence_len);
+        }
+    }
+}
+
+void release_epaperdisplay(displayio_epaperdisplay_obj_t* self) {
+    if (self->refreshing) {
+        wait_for_busy(self);
+        self->refreshing = false;
+        // Run stop sequence but don't wait for busy because busy is set when sleeping.
+        send_command_sequence(self, false, self->stop_sequence, self->stop_sequence_len);
+    }
+
+    release_display_core(&self->core);
+    if (self->busy.base.type == &digitalio_digitalinout_type) {
+        common_hal_digitalio_digitalinout_deinit(&self->busy);
+    }
+}
+
+void displayio_epaperdisplay_collect_ptrs(displayio_epaperdisplay_obj_t* self) {
+    displayio_display_core_collect_ptrs(&self->core);
+}
+
+bool maybe_refresh_epaperdisplay(void) {
+    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
+        if (displays[i].epaper_display.base.type != &displayio_epaperdisplay_type ||
+            displays[i].epaper_display.core.current_group != &circuitpython_splash) {
+            // Skip regular displays and those not showing the splash.
+            continue;
+        }
+        displayio_epaperdisplay_obj_t* display = &displays[i].epaper_display;
+        if (common_hal_displayio_epaperdisplay_get_time_to_refresh(display) != 0) {
+            return false;
+        }
+        return common_hal_displayio_epaperdisplay_refresh(display);
+    }
+    // Return true if no ePaper displays are available to pretend it was updated.
+    return true;
+}
diff --git a/shared-module/displayio/EPaperDisplay.h b/shared-module/displayio/EPaperDisplay.h
new file mode 100644
index 000000000..d08bed546
--- /dev/null
+++ b/shared-module/displayio/EPaperDisplay.h
@@ -0,0 +1,68 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_EPAPERDISPLAY_H
+#define MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_EPAPERDISPLAY_H
+
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-bindings/displayio/Group.h"
+#include "shared-bindings/pulseio/PWMOut.h"
+
+#include "shared-module/displayio/area.h"
+#include "shared-module/displayio/display_core.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    displayio_display_core_t core;
+    digitalio_digitalinout_obj_t busy;
+    uint32_t milliseconds_per_frame;
+    uint8_t* start_sequence;
+    uint32_t start_sequence_len;
+    uint8_t* stop_sequence;
+    uint32_t stop_sequence_len;
+    uint16_t refresh_time;
+    uint16_t set_column_window_command;
+    uint16_t set_row_window_command;
+    uint16_t set_current_column_command;
+    uint16_t set_current_row_command;
+    uint16_t write_black_ram_command;
+    uint16_t write_color_ram_command;
+    uint8_t refresh_display_command;
+    uint8_t hue;
+    bool busy_state;
+    bool black_bits_inverted;
+    bool color_bits_inverted;
+    bool refreshing;
+    display_chip_select_behavior_t chip_select;
+} displayio_epaperdisplay_obj_t;
+
+void displayio_epaperdisplay_background(displayio_epaperdisplay_obj_t* self);
+void release_epaperdisplay(displayio_epaperdisplay_obj_t* self);
+bool maybe_refresh_epaperdisplay(void);
+
+void displayio_epaperdisplay_collect_ptrs(displayio_epaperdisplay_obj_t* self);
+
+#endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_EPAPERDISPLAY_H
diff --git a/shared-module/displayio/FourWire.c b/shared-module/displayio/FourWire.c
index 913635db8..fcc4c1a20 100644
--- a/shared-module/displayio/FourWire.c
+++ b/shared-module/displayio/FourWire.c
@@ -33,6 +33,7 @@
 #include "shared-bindings/digitalio/DigitalInOut.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/time/__init__.h"
+#include "shared-module/displayio/display_core.h"
 
 #include "tick.h"
 
@@ -55,15 +56,13 @@ void common_hal_displayio_fourwire_construct(displayio_fourwire_obj_t* self,
     common_hal_digitalio_digitalinout_construct(&self->chip_select, chip_select);
     common_hal_digitalio_digitalinout_switch_to_output(&self->chip_select, true, DRIVE_MODE_PUSH_PULL);
 
+    self->reset.base.type = &mp_type_NoneType;
     if (reset != NULL) {
+        self->reset.base.type = &digitalio_digitalinout_type;
         common_hal_digitalio_digitalinout_construct(&self->reset, reset);
         common_hal_digitalio_digitalinout_switch_to_output(&self->reset, true, DRIVE_MODE_PUSH_PULL);
         never_reset_pin_number(reset->number);
-
-        common_hal_digitalio_digitalinout_set_value(&self->reset, false);
-        common_hal_mcu_delay_us(10);
-        common_hal_digitalio_digitalinout_set_value(&self->reset, true);
-        common_hal_mcu_delay_us(10);
+        common_hal_displayio_fourwire_reset(self);
     }
 
     never_reset_pin_number(command->number);
@@ -80,6 +79,27 @@ void common_hal_displayio_fourwire_deinit(displayio_fourwire_obj_t* self) {
     reset_pin_number(self->reset.pin->number);
 }
 
+bool common_hal_displayio_fourwire_reset(mp_obj_t obj) {
+    displayio_fourwire_obj_t* self = MP_OBJ_TO_PTR(obj);
+    if (self->reset.base.type == &mp_type_NoneType) {
+        return false;
+    }
+    common_hal_digitalio_digitalinout_set_value(&self->reset, false);
+    common_hal_time_delay_ms(1);
+    common_hal_digitalio_digitalinout_set_value(&self->reset, true);
+    common_hal_time_delay_ms(1);
+    return true;
+}
+
+bool common_hal_displayio_fourwire_bus_free(mp_obj_t obj) {
+    displayio_fourwire_obj_t* self = MP_OBJ_TO_PTR(obj);
+    if (!common_hal_busio_spi_try_lock(self->bus)) {
+        return false;
+    }
+    common_hal_busio_spi_unlock(self->bus);
+    return true;
+}
+
 bool common_hal_displayio_fourwire_begin_transaction(mp_obj_t obj) {
     displayio_fourwire_obj_t* self = MP_OBJ_TO_PTR(obj);
     if (!common_hal_busio_spi_try_lock(self->bus)) {
@@ -91,10 +111,10 @@ bool common_hal_displayio_fourwire_begin_transaction(mp_obj_t obj) {
     return true;
 }
 
-void common_hal_displayio_fourwire_send(mp_obj_t obj, bool command, uint8_t *data, uint32_t data_length) {
+void common_hal_displayio_fourwire_send(mp_obj_t obj, display_byte_type_t data_type, display_chip_select_behavior_t chip_select, uint8_t *data, uint32_t data_length) {
     displayio_fourwire_obj_t* self = MP_OBJ_TO_PTR(obj);
-    common_hal_digitalio_digitalinout_set_value(&self->command, !command);
-    if (command) {
+    common_hal_digitalio_digitalinout_set_value(&self->command, data_type == DISPLAY_DATA);
+    if (chip_select == CHIP_SELECT_TOGGLE_EVERY_BYTE) {
         // Toggle chip select after each command byte in case the display driver
         // IC latches commands based on it.
         for (size_t i = 0; i < data_length; i++) {
diff --git a/shared-module/displayio/I2CDisplay.c b/shared-module/displayio/I2CDisplay.c
index 9d8949528..87261dca0 100644
--- a/shared-module/displayio/I2CDisplay.c
+++ b/shared-module/displayio/I2CDisplay.c
@@ -35,6 +35,7 @@
 #include "shared-bindings/digitalio/DigitalInOut.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/time/__init__.h"
+#include "shared-module/displayio/display_core.h"
 
 #include "tick.h"
 
@@ -55,14 +56,13 @@ void common_hal_displayio_i2cdisplay_construct(displayio_i2cdisplay_obj_t* self,
 
     self->address = device_address;
 
+    self->reset.base.type = &mp_type_NoneType;
     if (reset != NULL) {
+        self->reset.base.type = &digitalio_digitalinout_type;
         common_hal_digitalio_digitalinout_construct(&self->reset, reset);
         common_hal_digitalio_digitalinout_switch_to_output(&self->reset, true, DRIVE_MODE_PUSH_PULL);
         never_reset_pin_number(reset->number);
-
-        common_hal_digitalio_digitalinout_set_value(&self->reset, false);
-        common_hal_mcu_delay_us(1);
-        common_hal_digitalio_digitalinout_set_value(&self->reset, true);
+        common_hal_displayio_i2cdisplay_reset(self);
     }
 }
 
@@ -74,7 +74,19 @@ void common_hal_displayio_i2cdisplay_deinit(displayio_i2cdisplay_obj_t* self) {
     reset_pin_number(self->reset.pin->number);
 }
 
-bool common_hal_displayio_i2cdisplay_begin_transaction(mp_obj_t obj) {
+bool common_hal_displayio_i2cdisplay_reset(mp_obj_t obj) {
+    displayio_i2cdisplay_obj_t* self = MP_OBJ_TO_PTR(obj);
+    if (self->reset.base.type == &mp_type_NoneType) {
+        return false;
+    }
+
+    common_hal_digitalio_digitalinout_set_value(&self->reset, false);
+    common_hal_mcu_delay_us(4);
+    common_hal_digitalio_digitalinout_set_value(&self->reset, true);
+    return true;
+}
+
+bool common_hal_displayio_i2cdisplay_bus_free(mp_obj_t obj) {
     displayio_i2cdisplay_obj_t* self = MP_OBJ_TO_PTR(obj);
     if (!common_hal_busio_i2c_try_lock(self->bus)) {
         return false;
@@ -82,9 +94,13 @@ bool common_hal_displayio_i2cdisplay_begin_transaction(mp_obj_t obj) {
     return true;
 }
 
-void common_hal_displayio_i2cdisplay_send(mp_obj_t obj, bool command, uint8_t *data, uint32_t data_length) {
+bool common_hal_displayio_i2cdisplay_begin_transaction(mp_obj_t obj) {
+    return common_hal_displayio_i2cdisplay_bus_free(obj);
+}
+
+void common_hal_displayio_i2cdisplay_send(mp_obj_t obj, display_byte_type_t data_type, display_chip_select_behavior_t chip_select, uint8_t *data, uint32_t data_length) {
     displayio_i2cdisplay_obj_t* self = MP_OBJ_TO_PTR(obj);
-    if (command) {
+    if (data_type == DISPLAY_COMMAND) {
         uint8_t command_bytes[2 * data_length];
         for (uint32_t i = 0; i < data_length; i++) {
             command_bytes[2 * i] = 0x80;
diff --git a/shared-module/displayio/OnDiskBitmap.c b/shared-module/displayio/OnDiskBitmap.c
index 2b5642437..993fc03de 100644
--- a/shared-module/displayio/OnDiskBitmap.c
+++ b/shared-module/displayio/OnDiskBitmap.c
@@ -74,7 +74,7 @@ void common_hal_displayio_ondiskbitmap_construct(displayio_ondiskbitmap_t *self,
             self->g_bitmask = 0x3e0;
             self->b_bitmask = 0x1f;
         }
-    } else if ((indexed) && (self->bits_per_pixel != 1)) {
+    } else if (indexed && self->bits_per_pixel != 1) {
         uint16_t palette_size = number_of_colors * sizeof(uint32_t);
         uint16_t palette_offset = 0xe + header_size;
 
@@ -90,25 +90,24 @@ void common_hal_displayio_ondiskbitmap_construct(displayio_ondiskbitmap_t *self,
         if (palette_bytes_read != palette_size) {
             mp_raise_ValueError(translate("Unable to read color palette data"));
         }
-
-
     } else if (!(header_size == 12 || header_size == 40 || header_size == 108 || header_size == 124)) {
         mp_raise_ValueError_varg(translate("Only Windows format, uncompressed BMP supported: given header size is %d"), header_size);
     }
 
-    if ((bits_per_pixel == 4 ) || (( bits_per_pixel == 8) && (number_of_colors == 0))) {
-        mp_raise_ValueError_varg(translate("Only monochrome, indexed 8bpp, and 16bpp or greater BMPs supported: %d bpp given"), bits_per_pixel);
+    if (bits_per_pixel == 8 && number_of_colors == 0) {
+        mp_raise_ValueError_varg(translate("Only monochrome, indexed 4bpp or 8bpp, and 16bpp or greater BMPs supported: %d bpp given"), bits_per_pixel);
     }
 
-    if (self->bits_per_pixel >=8){
-        self->stride = (self->width * (bits_per_pixel / 8));
+    uint8_t bytes_per_pixel = (self->bits_per_pixel / 8)  ? (self->bits_per_pixel /8) : 1;
+    uint8_t pixels_per_byte = 8 / self->bits_per_pixel;
+    if (pixels_per_byte == 0){
+        self->stride = (self->width * bytes_per_pixel);
         // Rows are word aligned.
         if (self->stride % 4 != 0) {
             self->stride += 4 - self->stride % 4;
         }
-
     } else {
-        uint32_t bit_stride = self->width;
+        uint32_t bit_stride = self->width * self->bits_per_pixel;
         if (bit_stride % 32 != 0) {
             bit_stride += 32 - bit_stride % 32;
         }
@@ -126,10 +125,11 @@ uint32_t common_hal_displayio_ondiskbitmap_get_pixel(displayio_ondiskbitmap_t *s
 
     uint32_t location;
     uint8_t bytes_per_pixel = (self->bits_per_pixel / 8)  ? (self->bits_per_pixel /8) : 1;
-    if (self->bits_per_pixel >= 8){
+    uint8_t pixels_per_byte = 8 / self->bits_per_pixel;
+    if (pixels_per_byte == 0){
         location = self->data_offset + (self->height - y - 1) * self->stride + x * bytes_per_pixel;
     } else {
-        location = self->data_offset + (self->height - y - 1) * self->stride + x / 8;
+        location = self->data_offset + (self->height - y - 1) * self->stride + x / pixels_per_byte;
     }
     // We don't cache here because the underlying FS caches sectors.
     f_lseek(&self->file->fp, location);
@@ -141,20 +141,19 @@ uint32_t common_hal_displayio_ondiskbitmap_get_pixel(displayio_ondiskbitmap_t *s
         uint8_t red;
         uint8_t green;
         uint8_t blue;
-        if (self->bits_per_pixel == 1) {
-            uint8_t bit_offset = x%8;
-            tmp = ( pixel_data & (0x80 >> (bit_offset))) >> (7 - bit_offset);
-            if (tmp == 1) {
-                return 0x00FFFFFF;
-            } else {
-                return 0x00000000;
+        if (bytes_per_pixel == 1) {
+            uint8_t offset = (x % pixels_per_byte) * self->bits_per_pixel;
+            uint8_t mask = (1 << self->bits_per_pixel) - 1;
+
+            uint8_t index = (pixel_data >> ((8 - self->bits_per_pixel) - offset)) & mask;
+            if (self->bits_per_pixel == 1) {
+                if (index == 1) {
+                    return 0xFFFFFF;
+                } else {
+                    return 0x000000;
+                }
             }
-        } else if (bytes_per_pixel == 1) {
-            blue = ((self->palette_data[pixel_data] & 0xFF) >> 0);
-            red = ((self->palette_data[pixel_data] & 0xFF0000) >> 16);
-            green = ((self->palette_data[pixel_data] & 0xFF00) >> 8);
-            tmp = (red << 16 | green << 8 | blue );
-            return tmp;
+            return self->palette_data[index];
         } else if (bytes_per_pixel == 2) {
             if (self->g_bitmask == 0x07e0) { // 565
                 red =((pixel_data & self->r_bitmask) >>11);
diff --git a/shared-module/displayio/Palette.c b/shared-module/displayio/Palette.c
index 444151b3c..3bce86f48 100644
--- a/shared-module/displayio/Palette.c
+++ b/shared-module/displayio/Palette.c
@@ -52,6 +52,10 @@ void common_hal_displayio_palette_set_color(displayio_palette_t* self, uint32_t
     self->colors[palette_index].rgb888 = color;
     self->colors[palette_index].luma = displayio_colorconverter_compute_luma(color);
     self->colors[palette_index].rgb565 = displayio_colorconverter_compute_rgb565(color);
+
+    uint8_t chroma = displayio_colorconverter_compute_chroma(color);
+    self->colors[palette_index].chroma = chroma;
+    self->colors[palette_index].hue = displayio_colorconverter_compute_hue(color);
     self->needs_refresh = true;
 }
 
@@ -64,7 +68,19 @@ bool displayio_palette_get_color(displayio_palette_t *self, const _displayio_col
         return false; // returns opaque
     }
 
-    if (colorspace->grayscale) {
+    if (colorspace->tricolor) {
+        uint8_t luma = self->colors[palette_index].luma;
+        *color = luma >> (8 - colorspace->depth);
+        // Chroma 0 means the color is a gray and has no hue so never color based on it.
+        if (self->colors[palette_index].chroma  <= 16) {
+            if (!colorspace->grayscale) {
+                *color = 0;
+            }
+            return true;
+        }
+        uint8_t pixel_hue = self->colors[palette_index].hue;
+        displayio_colorconverter_compute_tricolor(colorspace, pixel_hue, luma, color);
+    } else if (colorspace->grayscale) {
         *color = self->colors[palette_index].luma >> (8 - colorspace->depth);
     } else {
         *color = self->colors[palette_index].rgb565;
diff --git a/shared-module/displayio/Palette.h b/shared-module/displayio/Palette.h
index a917e2432..1cfdd199a 100644
--- a/shared-module/displayio/Palette.h
+++ b/shared-module/displayio/Palette.h
@@ -34,17 +34,21 @@
 
 typedef struct {
     uint8_t depth;
+    uint8_t bytes_per_cell;
+    uint8_t tricolor_hue;
+    uint8_t tricolor_luma;
     bool grayscale;
+    bool tricolor;
     bool pixels_in_byte_share_row;
-    uint8_t bytes_per_cell;
     bool reverse_pixels_in_byte;
-    uint8_t hue;
 } _displayio_colorspace_t;
 
 typedef struct {
     uint32_t rgb888;
     uint16_t rgb565;
     uint8_t luma;
+    uint8_t hue;
+    uint8_t chroma;
     bool transparent; // This may have additional bits added later for blending.
 } _displayio_color_t;
 
diff --git a/shared-module/displayio/TileGrid.c b/shared-module/displayio/TileGrid.c
index 6144f8f99..f34d2fc52 100644
--- a/shared-module/displayio/TileGrid.c
+++ b/shared-module/displayio/TileGrid.c
@@ -207,7 +207,7 @@ uint8_t common_hal_displayio_tilegrid_get_tile(displayio_tilegrid_t *self, uint1
 
 void common_hal_displayio_tilegrid_set_tile(displayio_tilegrid_t *self, uint16_t x, uint16_t y, uint8_t tile_index) {
     if (tile_index >= self->tiles_in_bitmap) {
-        mp_raise_ValueError(translate("Tile value out of bounds"));
+        mp_raise_ValueError(translate("Tile index out of bounds"));
     }
     uint8_t* tiles = self->tiles;
     if (self->inline_tiles) {
@@ -443,6 +443,7 @@ bool displayio_tilegrid_fill_area(displayio_tilegrid_t *self, const _displayio_c
                     }
                     uint8_t shift = (offset % pixels_per_byte) * colorspace->depth;
                     if (colorspace->reverse_pixels_in_byte) {
+                        // Reverse the shift by subtracting it from the leftmost shift.
                         shift = (pixels_per_byte - 1) * colorspace->depth - shift;
                     }
                     ((uint8_t*)buffer)[offset / pixels_per_byte] |= pixel << shift;
diff --git a/shared-module/displayio/TileGrid.h b/shared-module/displayio/TileGrid.h
index 222aaed19..0a414b062 100644
--- a/shared-module/displayio/TileGrid.h
+++ b/shared-module/displayio/TileGrid.h
@@ -43,7 +43,7 @@ typedef struct {
     uint16_t pixel_width;
     uint16_t pixel_height;
     uint16_t bitmap_width_in_tiles;;
-    uint8_t tiles_in_bitmap;
+    uint16_t tiles_in_bitmap;
     uint16_t width_in_tiles;
     uint16_t height_in_tiles;
     uint16_t tile_width;
diff --git a/shared-module/displayio/__init__.c b/shared-module/displayio/__init__.c
index 3e9c4aa2a..af22cb0df 100644
--- a/shared-module/displayio/__init__.c
+++ b/shared-module/displayio/__init__.c
@@ -4,7 +4,6 @@
 #include "shared-module/displayio/__init__.h"
 
 #include "lib/utils/interrupt_char.h"
-#include "py/gc.h"
 #include "py/reload.h"
 #include "py/runtime.h"
 #include "shared-bindings/board/__init__.h"
@@ -16,103 +15,13 @@
 #include "supervisor/shared/autoreload.h"
 #include "supervisor/shared/display.h"
 #include "supervisor/memory.h"
-#include "supervisor/usb.h"
 
 primary_display_t displays[CIRCUITPY_DISPLAY_LIMIT];
-uint32_t frame_count = 0;
 
-bool refresh_area(displayio_display_obj_t* display, const displayio_area_t* area) {
-    uint16_t buffer_size = 128; // In uint32_ts
+// Check for recursive calls to displayio_background.
+bool displayio_background_in_progress = false;
 
-    displayio_area_t clipped;
-    // Clip the area to the display by overlapping the areas. If there is no overlap then we're done.
-    if (!displayio_display_clip_area(display, area, &clipped)) {
-        return true;
-    }
-    uint16_t subrectangles = 1;
-    uint16_t rows_per_buffer = displayio_area_height(&clipped);
-    uint8_t pixels_per_word = (sizeof(uint32_t) * 8) / display->colorspace.depth;
-    uint16_t pixels_per_buffer = displayio_area_size(&clipped);
-    if (displayio_area_size(&clipped) > buffer_size * pixels_per_word) {
-        rows_per_buffer = buffer_size * pixels_per_word / displayio_area_width(&clipped);
-        if (rows_per_buffer == 0) {
-            rows_per_buffer = 1;
-        }
-        // If pixels are packed by column then ensure rows_per_buffer is on a byte boundary.
-        if (display->colorspace.depth < 8 && !display->colorspace.pixels_in_byte_share_row) {
-            uint8_t pixels_per_byte = 8 / display->colorspace.depth;
-            if (rows_per_buffer % pixels_per_byte != 0) {
-                rows_per_buffer -= rows_per_buffer % pixels_per_byte;
-            }
-        }
-        subrectangles = displayio_area_height(&clipped) / rows_per_buffer;
-        if (displayio_area_height(&clipped) % rows_per_buffer != 0) {
-            subrectangles++;
-        }
-        pixels_per_buffer = rows_per_buffer * displayio_area_width(&clipped);
-        buffer_size = pixels_per_buffer / pixels_per_word;
-        if (pixels_per_buffer % pixels_per_word) {
-            buffer_size += 1;
-        }
-    }
-
-    // Allocated and shared as a uint32_t array so the compiler knows the
-    // alignment everywhere.
-    uint32_t buffer[buffer_size];
-    volatile uint32_t mask_length = (pixels_per_buffer / 32) + 1;
-    uint32_t mask[mask_length];
-    uint16_t remaining_rows = displayio_area_height(&clipped);
-
-    for (uint16_t j = 0; j < subrectangles; j++) {
-        displayio_area_t subrectangle = {
-            .x1 = clipped.x1,
-            .y1 = clipped.y1 + rows_per_buffer * j,
-            .x2 = clipped.x2,
-            .y2 = clipped.y1 + rows_per_buffer * (j + 1)
-        };
-        if (remaining_rows < rows_per_buffer) {
-            subrectangle.y2 = subrectangle.y1 + remaining_rows;
-        }
-        remaining_rows -= rows_per_buffer;
-
-        displayio_display_begin_transaction(display);
-        displayio_display_set_region_to_update(display, &subrectangle);
-        displayio_display_end_transaction(display);
-
-        uint16_t subrectangle_size_bytes;
-        if (display->colorspace.depth >= 8) {
-            subrectangle_size_bytes = displayio_area_size(&subrectangle) * (display->colorspace.depth / 8);
-        } else {
-            subrectangle_size_bytes = displayio_area_size(&subrectangle) / (8 / display->colorspace.depth);
-        }
-
-        for (uint16_t k = 0; k < mask_length; k++) {
-            mask[k] = 0x00000000;
-        }
-        for (uint16_t k = 0; k < buffer_size; k++) {
-            buffer[k] = 0x00000000;
-        }
-
-        displayio_display_fill_area(display, &subrectangle, mask, buffer);
-
-        if (!displayio_display_begin_transaction(display)) {
-            // Can't acquire display bus; skip the rest of the data. Try next display.
-            return false;
-        }
-        displayio_display_send_pixels(display, (uint8_t*) buffer, subrectangle_size_bytes);
-        displayio_display_end_transaction(display);
-
-        // TODO(tannewt): Make refresh displays faster so we don't starve other
-        // background tasks.
-        usb_background();
-    }
-    return true;
-}
-
-// Check for recursive calls to displayio_refresh_displays.
-bool refresh_displays_in_progress = false;
-
-void displayio_refresh_displays(void) {
+void displayio_background(void) {
     if (mp_hal_is_interrupted()) {
         return;
     }
@@ -121,46 +30,43 @@ void displayio_refresh_displays(void) {
         return;
     }
 
-    if (refresh_displays_in_progress) {
+    if (displayio_background_in_progress) {
         // Don't allow recursive calls to this routine.
         return;
     }
 
-    refresh_displays_in_progress = true;
+    displayio_background_in_progress = true;
 
     for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
         if (displays[i].display.base.type == NULL || displays[i].display.base.type == &mp_type_NoneType) {
             // Skip null display.
             continue;
         }
-        displayio_display_obj_t* display = &displays[i].display;
-        displayio_display_update_backlight(display);
-
-        // Time to refresh at specified frame rate?
-        if (!displayio_display_frame_queued(display)) {
-            // Too soon. Try next display.
-            continue;
-        }
-        if (!displayio_display_begin_transaction(display)) {
-            // Can't acquire display bus; skip updating this display. Try next display.
-            continue;
+        if (displays[i].display.base.type == &displayio_display_type) {
+            displayio_display_background(&displays[i].display);
+        } else if (displays[i].epaper_display.base.type == &displayio_epaperdisplay_type) {
+            displayio_epaperdisplay_background(&displays[i].epaper_display);
         }
-        displayio_display_end_transaction(display);
-        displayio_display_start_refresh(display);
-        const displayio_area_t* current_area = displayio_display_get_refresh_areas(display);
-        while (current_area != NULL) {
-            refresh_area(display, current_area);
-            current_area = current_area->next;
-        }
-        displayio_display_finish_refresh(display);
-        frame_count++;
     }
 
     // All done.
-    refresh_displays_in_progress = false;
+    displayio_background_in_progress = false;
 }
 
 void common_hal_displayio_release_displays(void) {
+    // Release displays before busses so that they can send any final commands to turn the display
+    // off properly.
+    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
+        mp_const_obj_t display_type = displays[i].display.base.type;
+        if (display_type == NULL || display_type == &mp_type_NoneType) {
+            continue;
+        } else if (display_type == &displayio_display_type) {
+            release_display(&displays[i].display);
+        } else if (display_type == &displayio_epaperdisplay_type) {
+            release_epaperdisplay(&displays[i].epaper_display);
+        }
+        displays[i].display.base.type = &mp_type_NoneType;
+    }
     for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
         mp_const_obj_t bus_type = displays[i].fourwire_bus.base.type;
         if (bus_type == NULL || bus_type == &mp_type_NoneType) {
@@ -174,10 +80,6 @@ void common_hal_displayio_release_displays(void) {
         }
         displays[i].fourwire_bus.base.type = &mp_type_NoneType;
     }
-    for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
-        release_display(&displays[i].display);
-        displays[i].display.base.type = &mp_type_NoneType;
-    }
 
     supervisor_stop_terminal();
 }
@@ -214,7 +116,7 @@ void reset_displays(void) {
                 ((uint32_t) i2c->bus) > ((uint32_t) &displays + CIRCUITPY_DISPLAY_LIMIT)) {
                 busio_i2c_obj_t* original_i2c = i2c->bus;
                 #if BOARD_I2C
-                    // We don't need to move original_i2c if it is the board.SPI object because it is
+                    // We don't need to move original_i2c if it is the board.I2C object because it is
                     // statically allocated already. (Doing so would also make it impossible to reference in
                     // a subsequent VM run.)
                     if (original_i2c == common_hal_board_get_i2c()) {
@@ -232,7 +134,7 @@ void reset_displays(void) {
                 }
             }
         } else {
-            // Not an active display.
+            // Not an active display bus.
             continue;
         }
     }
@@ -240,9 +142,12 @@ void reset_displays(void) {
     for (uint8_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
         // Reset the displayed group. Only the first will get the terminal but
         // that's ok.
-        displayio_display_obj_t* display = &displays[i].display;
-        display->auto_brightness = true;
-        common_hal_displayio_display_show(display, NULL);
+        if (displays[i].display.base.type == &displayio_display_type) {
+            reset_display(&displays[i].display);
+        } else if (displays[i].epaper_display.base.type == &displayio_epaperdisplay_type) {
+            displayio_epaperdisplay_obj_t* display = &displays[i].epaper_display;
+            common_hal_displayio_epaperdisplay_show(display, NULL);
+        }
     }
 }
 
@@ -254,8 +159,11 @@ void displayio_gc_collect(void) {
 
         // Alternatively, we could use gc_collect_root over the whole object,
         // but this is more precise, and is the only field that needs marking.
-        gc_collect_ptr(displays[i].display.current_group);
-
+        if (displays[i].display.base.type == &displayio_display_type) {
+            displayio_display_collect_ptrs(&displays[i].display);
+        } else if (displays[i].epaper_display.base.type == &displayio_epaperdisplay_type) {
+            displayio_epaperdisplay_collect_ptrs(&displays[i].epaper_display);
+        }
     }
 }
 
diff --git a/shared-module/displayio/__init__.h b/shared-module/displayio/__init__.h
index caa5ce36d..e78bc61ce 100644
--- a/shared-module/displayio/__init__.h
+++ b/shared-module/displayio/__init__.h
@@ -28,6 +28,7 @@
 #define MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO___INIT___H
 
 #include "shared-bindings/displayio/Display.h"
+#include "shared-bindings/displayio/EPaperDisplay.h"
 #include "shared-bindings/displayio/FourWire.h"
 #include "shared-bindings/displayio/Group.h"
 #include "shared-bindings/displayio/I2CDisplay.h"
@@ -39,14 +40,17 @@ typedef struct {
         displayio_i2cdisplay_obj_t i2cdisplay_bus;
         displayio_parallelbus_obj_t parallel_bus;
     };
-    displayio_display_obj_t display;
+    union {
+        displayio_display_obj_t display;
+        displayio_epaperdisplay_obj_t epaper_display;
+    };
 } primary_display_t;
 
 extern primary_display_t displays[CIRCUITPY_DISPLAY_LIMIT];
 
 extern displayio_group_t circuitpython_splash;
 
-void displayio_refresh_displays(void);
+void displayio_background(void);
 void reset_displays(void);
 void displayio_gc_collect(void);
 
diff --git a/shared-module/displayio/display_core.c b/shared-module/displayio/display_core.c
new file mode 100644
index 000000000..0f449ea34
--- /dev/null
+++ b/shared-module/displayio/display_core.c
@@ -0,0 +1,325 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "shared-bindings/displayio/Display.h"
+
+#include "py/gc.h"
+#include "py/runtime.h"
+#include "shared-bindings/displayio/FourWire.h"
+#include "shared-bindings/displayio/I2CDisplay.h"
+#include "shared-bindings/displayio/ParallelBus.h"
+#include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/time/__init__.h"
+#include "shared-module/displayio/__init__.h"
+#include "supervisor/shared/display.h"
+
+#include <stdint.h>
+#include <string.h>
+
+#include "tick.h"
+
+void displayio_display_core_construct(displayio_display_core_t* self,
+        mp_obj_t bus, uint16_t width, uint16_t height, uint16_t ram_width, uint16_t ram_height, int16_t colstart, int16_t rowstart, uint16_t rotation,
+        uint16_t color_depth, bool grayscale, bool pixels_in_byte_share_row, uint8_t bytes_per_cell, bool reverse_pixels_in_byte) {
+    self->colorspace.depth = color_depth;
+    self->colorspace.grayscale = grayscale;
+    self->colorspace.pixels_in_byte_share_row = pixels_in_byte_share_row;
+    self->colorspace.bytes_per_cell = bytes_per_cell;
+    self->colorspace.reverse_pixels_in_byte = reverse_pixels_in_byte;
+    self->current_group = NULL;
+    self->colstart = colstart;
+    self->rowstart = rowstart;
+    self->last_refresh = 0;
+
+    if (MP_OBJ_IS_TYPE(bus, &displayio_parallelbus_type)) {
+        self->bus_reset = common_hal_displayio_parallelbus_reset;
+        self->bus_free = common_hal_displayio_parallelbus_bus_free;
+        self->begin_transaction = common_hal_displayio_parallelbus_begin_transaction;
+        self->send = common_hal_displayio_parallelbus_send;
+        self->end_transaction = common_hal_displayio_parallelbus_end_transaction;
+    } else if (MP_OBJ_IS_TYPE(bus, &displayio_fourwire_type)) {
+        self->bus_reset = common_hal_displayio_fourwire_reset;
+        self->bus_free = common_hal_displayio_fourwire_bus_free;
+        self->begin_transaction = common_hal_displayio_fourwire_begin_transaction;
+        self->send = common_hal_displayio_fourwire_send;
+        self->end_transaction = common_hal_displayio_fourwire_end_transaction;
+    } else if (MP_OBJ_IS_TYPE(bus, &displayio_i2cdisplay_type)) {
+        self->bus_reset = common_hal_displayio_i2cdisplay_reset;
+        self->bus_free = common_hal_displayio_i2cdisplay_bus_free;
+        self->begin_transaction = common_hal_displayio_i2cdisplay_begin_transaction;
+        self->send = common_hal_displayio_i2cdisplay_send;
+        self->end_transaction = common_hal_displayio_i2cdisplay_end_transaction;
+    } else {
+        mp_raise_ValueError(translate("Unsupported display bus type"));
+    }
+    self->bus = bus;
+
+
+    supervisor_start_terminal(width, height);
+
+    self->width = width;
+    self->height = height;
+    self->ram_width = ram_width;
+    self->ram_height = ram_height;
+    rotation = rotation % 360;
+    self->transform.x = 0;
+    self->transform.y = 0;
+    self->transform.scale = 1;
+    self->transform.mirror_x = false;
+    self->transform.mirror_y = false;
+    self->transform.transpose_xy = false;
+    if (rotation == 0 || rotation == 180) {
+        if (rotation == 180) {
+            self->transform.mirror_x = true;
+            self->transform.mirror_y = true;
+        }
+    } else {
+        self->transform.transpose_xy = true;
+        if (rotation == 270) {
+            self->transform.mirror_y = true;
+        } else {
+            self->transform.mirror_x = true;
+        }
+    }
+
+    self->area.x1 = 0;
+    self->area.y1 = 0;
+    self->area.next = NULL;
+
+    self->transform.dx = 1;
+    self->transform.dy = 1;
+    if (self->transform.transpose_xy) {
+        self->area.x2 = height;
+        self->area.y2 = width;
+        if (self->transform.mirror_x) {
+            self->transform.x = height;
+            self->transform.dx = -1;
+        }
+        if (self->transform.mirror_y) {
+            self->transform.y = width;
+            self->transform.dy = -1;
+        }
+    } else {
+        self->area.x2 = width;
+        self->area.y2 = height;
+        if (self->transform.mirror_x) {
+            self->transform.x = width;
+            self->transform.dx = -1;
+        }
+        if (self->transform.mirror_y) {
+            self->transform.y = height;
+            self->transform.dy = -1;
+        }
+    }
+}
+
+bool displayio_display_core_show(displayio_display_core_t* self, displayio_group_t* root_group) {
+    if (root_group == NULL) {
+        if (!circuitpython_splash.in_group) {
+            root_group = &circuitpython_splash;
+        } else if (self->current_group == &circuitpython_splash) {
+            return true;
+        }
+    }
+    if (root_group == self->current_group) {
+        return true;
+    }
+    if (root_group != NULL && root_group->in_group) {
+        return false;
+    }
+    if (self->current_group != NULL) {
+        self->current_group->in_group = false;
+    }
+
+    if (root_group != NULL) {
+        displayio_group_update_transform(root_group, &self->transform);
+        root_group->in_group = true;
+    }
+    self->current_group = root_group;
+    self->full_refresh = true;
+    return true;
+}
+
+uint16_t displayio_display_core_get_width(displayio_display_core_t* self){
+    return self->width;
+}
+
+uint16_t displayio_display_core_get_height(displayio_display_core_t* self){
+    return self->height;
+}
+
+bool displayio_display_core_bus_free(displayio_display_core_t *self) {
+    return self->bus_free(self->bus);
+}
+
+bool displayio_display_core_begin_transaction(displayio_display_core_t* self) {
+    return self->begin_transaction(self->bus);
+}
+
+void displayio_display_core_end_transaction(displayio_display_core_t* self) {
+    self->end_transaction(self->bus);
+}
+
+void displayio_display_core_set_region_to_update(displayio_display_core_t* self, uint8_t column_command, uint8_t row_command, uint16_t set_current_column_command, uint16_t set_current_row_command, bool data_as_commands, bool always_toggle_chip_select, displayio_area_t* area) {
+    uint16_t x1 = area->x1;
+    uint16_t x2 = area->x2;
+    uint16_t y1 = area->y1;
+    uint16_t y2 = area->y2;
+    // Collapse down the dimension where multiple pixels are in a byte.
+    if (self->colorspace.depth < 8) {
+        uint8_t pixels_per_byte = 8 / self->colorspace.depth;
+        if (self->colorspace.pixels_in_byte_share_row) {
+            x1 /= pixels_per_byte * self->colorspace.bytes_per_cell;
+            x2 /= pixels_per_byte * self->colorspace.bytes_per_cell;
+        } else {
+            y1 /= pixels_per_byte * self->colorspace.bytes_per_cell;
+            y2 /= pixels_per_byte * self->colorspace.bytes_per_cell;
+        }
+    }
+
+    display_chip_select_behavior_t chip_select = CHIP_SELECT_UNTOUCHED;
+    if (always_toggle_chip_select || data_as_commands) {
+        chip_select = CHIP_SELECT_TOGGLE_EVERY_BYTE;
+    }
+
+    // Set column.
+    displayio_display_core_begin_transaction(self);
+    uint8_t data[5];
+    data[0] = column_command;
+    uint8_t data_length = 1;
+    display_byte_type_t data_type = DISPLAY_DATA;
+    if (!data_as_commands) {
+        self->send(self->bus, DISPLAY_COMMAND, CHIP_SELECT_UNTOUCHED, data, 1);
+        data_length = 0;
+    } else {
+        data_type = DISPLAY_COMMAND;
+    }
+    if (self->ram_width < 0x100) {
+        data[data_length++] = x1 + self->colstart;
+        data[data_length++] = x2 - 1 + self->colstart;
+    } else {
+        x1 += self->colstart;
+        x2 += self->colstart - 1;
+        data[data_length++] = x1 >> 8;
+        data[data_length++] = x1 & 0xff;
+        data[data_length++] = x2 >> 8;
+        data[data_length++] = x2 & 0xff;
+    }
+    self->send(self->bus, data_type, chip_select, data, data_length);
+    displayio_display_core_end_transaction(self);
+    if (set_current_column_command != NO_COMMAND) {
+        uint8_t command = set_current_column_command;
+        displayio_display_core_begin_transaction(self);
+        self->send(self->bus, DISPLAY_COMMAND, chip_select, &command, 1);
+        self->send(self->bus, DISPLAY_DATA, chip_select, data, data_length / 2);
+        displayio_display_core_end_transaction(self);
+    }
+
+
+    // Set row.
+    displayio_display_core_begin_transaction(self);
+    data[0] = row_command;
+    data_length = 1;
+    if (!data_as_commands) {
+        self->send(self->bus, DISPLAY_COMMAND, CHIP_SELECT_UNTOUCHED, data, 1);
+        data_length = 0;
+    }
+    if (self->ram_height < 0x100) {
+        data[data_length++] = y1 + self->rowstart;
+        data[data_length++] = y2 - 1 + self->rowstart;
+    } else {
+        y1 += self->rowstart;
+        y2 += self->rowstart - 1;
+        data[data_length++] = y1 >> 8;
+        data[data_length++] = y1 & 0xff;
+        data[data_length++] = y2 >> 8;
+        data[data_length++] = y2 & 0xff;
+    }
+    self->send(self->bus, data_type, chip_select, data, data_length);
+    displayio_display_core_end_transaction(self);
+
+    if (set_current_row_command != NO_COMMAND) {
+        uint8_t command = set_current_row_command;
+        displayio_display_core_begin_transaction(self);
+        self->send(self->bus, DISPLAY_COMMAND, chip_select, &command, 1);
+        self->send(self->bus, DISPLAY_DATA, chip_select, data, data_length / 2);
+        displayio_display_core_end_transaction(self);
+    }
+}
+
+void displayio_display_core_start_refresh(displayio_display_core_t* self) {
+    self->last_refresh = ticks_ms;
+}
+
+void displayio_display_core_finish_refresh(displayio_display_core_t* self) {
+    if (self->current_group != NULL) {
+        displayio_group_finish_refresh(self->current_group);
+    }
+    self->full_refresh = false;
+    self->last_refresh = ticks_ms;
+}
+
+void release_display_core(displayio_display_core_t* self) {
+    if (self->current_group != NULL) {
+        self->current_group->in_group = false;
+    }
+}
+
+void displayio_display_core_collect_ptrs(displayio_display_core_t* self) {
+    gc_collect_ptr(self->current_group);
+}
+
+bool displayio_display_core_fill_area(displayio_display_core_t *self, displayio_area_t* area, uint32_t* mask, uint32_t *buffer) {
+    return displayio_group_fill_area(self->current_group, &self->colorspace, area, mask, buffer);
+}
+
+bool displayio_display_core_clip_area(displayio_display_core_t *self, const displayio_area_t* area, displayio_area_t* clipped) {
+    bool overlaps = displayio_area_compute_overlap(&self->area, area, clipped);
+    if (!overlaps) {
+        return false;
+    }
+    // Expand the area if we have multiple pixels per byte and we need to byte
+    // align the bounds.
+    if (self->colorspace.depth < 8) {
+        uint8_t pixels_per_byte = 8 / self->colorspace.depth * self->colorspace.bytes_per_cell;
+        if (self->colorspace.pixels_in_byte_share_row) {
+            if (clipped->x1 % pixels_per_byte != 0) {
+                clipped->x1 -= clipped->x1 % pixels_per_byte;
+            }
+            if (clipped->x2 % pixels_per_byte != 0) {
+                clipped->x2 += pixels_per_byte - clipped->x2 % pixels_per_byte;
+            }
+        } else {
+            if (clipped->y1 % pixels_per_byte != 0) {
+                clipped->y1 -= clipped->y1 % pixels_per_byte;
+            }
+            if (clipped->y2 % pixels_per_byte != 0) {
+                clipped->y2 += pixels_per_byte - clipped->y2 % pixels_per_byte;
+            }
+        }
+    }
+    return true;
+}
diff --git a/shared-module/displayio/display_core.h b/shared-module/displayio/display_core.h
new file mode 100644
index 000000000..e92fdbc9f
--- /dev/null
+++ b/shared-module/displayio/display_core.h
@@ -0,0 +1,85 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_DISPLAY_CORE_H
+#define MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_DISPLAY_CORE_H
+
+#include "shared-bindings/displayio/__init__.h"
+#include "shared-bindings/displayio/Group.h"
+
+#include "shared-module/displayio/area.h"
+
+#define NO_COMMAND 0x100
+
+typedef struct {
+    mp_obj_t bus;
+    displayio_group_t *current_group;
+    uint64_t last_refresh;
+    display_bus_bus_reset bus_reset;
+    display_bus_bus_free bus_free;
+    display_bus_begin_transaction begin_transaction;
+    display_bus_send send;
+    display_bus_end_transaction end_transaction;
+    displayio_buffer_transform_t transform;
+    displayio_area_t area;
+    uint16_t width;
+    uint16_t height;
+    uint16_t rotation;
+    uint16_t ram_width;
+    uint16_t ram_height;
+    _displayio_colorspace_t colorspace;
+    int16_t colstart;
+    int16_t rowstart;
+    bool full_refresh; // New group means we need to refresh the whole display.
+} displayio_display_core_t;
+
+void displayio_display_core_construct(displayio_display_core_t* self,
+        mp_obj_t bus, uint16_t width, uint16_t height, uint16_t ram_width, uint16_t ram_height, int16_t colstart, int16_t rowstart, uint16_t rotation,
+        uint16_t color_depth, bool grayscale, bool pixels_in_byte_share_row, uint8_t bytes_per_cell, bool reverse_pixels_in_byte);
+
+bool displayio_display_core_show(displayio_display_core_t* self, displayio_group_t* root_group);
+
+uint16_t displayio_display_core_get_width(displayio_display_core_t* self);
+uint16_t displayio_display_core_get_height(displayio_display_core_t* self);
+
+bool displayio_display_core_bus_free(displayio_display_core_t *self);
+bool displayio_display_core_begin_transaction(displayio_display_core_t* self);
+void displayio_display_core_end_transaction(displayio_display_core_t* self);
+
+void displayio_display_core_set_region_to_update(displayio_display_core_t* self, uint8_t column_command, uint8_t row_command, uint16_t set_current_column_command, uint16_t set_current_row_command, bool data_as_commands, bool always_toggle_chip_select, displayio_area_t* area);
+
+void release_display_core(displayio_display_core_t* self);
+
+void displayio_display_core_start_refresh(displayio_display_core_t* self);
+void displayio_display_core_finish_refresh(displayio_display_core_t* self);
+
+void displayio_display_core_collect_ptrs(displayio_display_core_t* self);
+
+bool displayio_display_core_fill_area(displayio_display_core_t *self, displayio_area_t* area, uint32_t* mask, uint32_t *buffer);
+
+bool displayio_display_core_clip_area(displayio_display_core_t *self, const displayio_area_t* area, displayio_area_t* clipped);
+
+#endif // MICROPY_INCLUDED_SHARED_MODULE_DISPLAYIO_DISPLAY_CORE_H