Add initial I2C support, not quite working fully though

13 files changed, 1085 insertions, 3 deletions

diff --git a/ports/esp32s2/Makefile b/ports/esp32s2/Makefile
index 5ad5c2f1d..4eac07f99 100644
--- a/ports/esp32s2/Makefile
+++ b/ports/esp32s2/Makefile
@@ -78,6 +78,7 @@ INC += -Iesp-idf/components/freertos/xtensa/include
 INC += -Iesp-idf/components/esp32s2/include
 INC += -Iesp-idf/components/xtensa/esp32s2/include
 INC += -Iesp-idf/components/esp_common/include
+INC += -Iesp-idf/components/esp_ringbuf/include
 INC += -Iesp-idf/components/esp_rom/include
 INC += -Iesp-idf/components/xtensa/include
 INC += -Iesp-idf/components/esp_timer/include
diff --git a/ports/esp32s2/common-hal/busio/I2C.c b/ports/esp32s2/common-hal/busio/I2C.c
new file mode 100644
index 000000000..80743dc89
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/I2C.c
@@ -0,0 +1,239 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft
+ *
+ * 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/busio/I2C.h"
+#include "py/mperrno.h"
+#include "py/runtime.h"
+
+#include "driver/i2c.h"
+
+#include "esp_log.h"
+
+#include "shared-bindings/microcontroller/__init__.h"
+#include "supervisor/shared/translate.h"
+
+// Number of times to try to send packet if failed.
+#define ATTEMPTS 2
+
+static const char* TAG = "CircuitPython I2C";
+
+typedef enum {
+    STATUS_FREE = 0,
+    STATUS_IN_USE,
+    STATUS_NEVER_RESET
+} i2c_status_t;
+
+static i2c_status_t i2c_status[I2C_NUM_MAX];
+
+void never_reset_i2c(i2c_port_t num) {
+    i2c_status[num] = STATUS_NEVER_RESET;
+}
+
+void i2c_reset(void) {
+    for (i2c_port_t num = 0; num < I2C_NUM_MAX; num++) {
+        if (i2c_status[num] == STATUS_IN_USE) {
+            i2c_driver_delete(num);
+            i2c_status[num] = STATUS_FREE;
+        }
+    }
+}
+
+void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
+        const mcu_pin_obj_t* scl, const mcu_pin_obj_t* sda, uint32_t frequency, uint32_t timeout) {
+
+    // Make sure scl and sda aren't input only
+
+#if CIRCUITPY_REQUIRE_I2C_PULLUPS
+    // // Test that the pins are in a high state. (Hopefully indicating they are pulled up.)
+    // gpio_set_pin_function(sda->number, GPIO_PIN_FUNCTION_OFF);
+    // gpio_set_pin_function(scl->number, GPIO_PIN_FUNCTION_OFF);
+    // gpio_set_pin_direction(sda->number, GPIO_DIRECTION_IN);
+    // gpio_set_pin_direction(scl->number, GPIO_DIRECTION_IN);
+
+    // gpio_set_pin_pull_mode(sda->number, GPIO_PULL_DOWN);
+    // gpio_set_pin_pull_mode(scl->number, GPIO_PULL_DOWN);
+
+    // common_hal_mcu_delay_us(10);
+
+    // gpio_set_pin_pull_mode(sda->number, GPIO_PULL_OFF);
+    // gpio_set_pin_pull_mode(scl->number, GPIO_PULL_OFF);
+
+    // // We must pull up within 3us to achieve 400khz.
+    // common_hal_mcu_delay_us(3);
+
+    // if (!gpio_get_pin_level(sda->number) || !gpio_get_pin_level(scl->number)) {
+    //     reset_pin_number(sda->number);
+    //     reset_pin_number(scl->number);
+    //     mp_raise_RuntimeError(translate("SDA or SCL needs a pull up"));
+    // }
+#endif
+    ESP_EARLY_LOGW(TAG, "create I2C");
+
+
+    self->semaphore_handle = xSemaphoreCreateBinaryStatic(&self->semaphore);
+    xSemaphoreGive(self->semaphore_handle);
+    ESP_EARLY_LOGW(TAG, "new I2C lock %x", self->semaphore_handle);
+    self->sda_pin = sda;
+    self->scl_pin = scl;
+    ESP_EARLY_LOGW(TAG, "scl %d sda %d", self->sda_pin->number, self->scl_pin->number);
+    self->i2c_num = I2C_NUM_MAX;
+    for (i2c_port_t num = 0; num < I2C_NUM_MAX; num++) {
+        if (i2c_status[num] == STATUS_FREE) {
+            self->i2c_num = num;
+        }
+    }
+    if (self->i2c_num == I2C_NUM_MAX) {
+        mp_raise_ValueError(translate("All I2C peripherals are in use"));
+    }
+    i2c_status[self->i2c_num] = STATUS_IN_USE;
+    i2c_config_t i2c_conf = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = self->sda_pin->number,
+        .scl_io_num = self->scl_pin->number,
+        .sda_pullup_en = GPIO_PULLUP_DISABLE,  /*!< Internal GPIO pull mode for I2C sda signal*/
+        .scl_pullup_en = GPIO_PULLUP_DISABLE,  /*!< Internal GPIO pull mode for I2C scl signal*/
+
+        .master = {
+            .clk_speed = frequency,
+        }
+    };
+    // ESP_EARLY_LOGW(TAG, "param config %p %p %d %d", &i2c_conf, &(i2c_conf.mode), i2c_conf.mode, I2C_MODE_MAX);
+    ESP_EARLY_LOGW(TAG, "param config %p %d %d", &i2c_conf, i2c_conf.mode, I2C_MODE_MAX);
+    esp_err_t result = i2c_param_config(self->i2c_num, &i2c_conf);
+    if (result != ESP_OK) {
+        ESP_EARLY_LOGW(TAG, "error %d %p %d %d", result, &i2c_conf, (&i2c_conf)->mode, I2C_MODE_MAX);
+        vTaskDelay(0);
+        mp_raise_ValueError(translate("Invalid pins"));
+    }
+    ESP_EARLY_LOGW(TAG, "param config I2C done");
+    result = i2c_driver_install(self->i2c_num,
+                                I2C_MODE_MASTER,
+                                0,
+                                0,
+                                0);
+    if (result != ESP_OK) {
+        mp_raise_OSError(MP_EIO);
+    }
+
+    claim_pin(sda);
+    claim_pin(scl);
+    ESP_EARLY_LOGW(TAG, "create I2C done");
+}
+
+bool common_hal_busio_i2c_deinited(busio_i2c_obj_t *self) {
+    return self->sda_pin == NULL;
+}
+
+void common_hal_busio_i2c_deinit(busio_i2c_obj_t *self) {
+    if (common_hal_busio_i2c_deinited(self)) {
+        return;
+    }
+
+    i2c_driver_delete(self->i2c_num);
+    i2c_status[self->i2c_num] = STATUS_FREE;
+
+    reset_pin(self->sda_pin);
+    reset_pin(self->scl_pin);
+    self->sda_pin = NULL;
+    self->scl_pin = NULL;
+}
+
+bool common_hal_busio_i2c_probe(busio_i2c_obj_t *self, uint8_t addr) {
+    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
+    i2c_master_start(cmd);
+    i2c_master_write_byte(cmd, addr << 1, true);
+    i2c_master_stop(cmd);
+    esp_err_t result = i2c_master_cmd_begin(self->i2c_num, cmd, 100);
+    i2c_cmd_link_delete(cmd);
+    return result == ESP_OK;
+}
+
+bool common_hal_busio_i2c_try_lock(busio_i2c_obj_t *self) {
+    ESP_EARLY_LOGW(TAG, "locking I2C %x", self->semaphore_handle);
+    self->has_lock = xSemaphoreTake(self->semaphore_handle, 0) == pdTRUE;
+    if (self->has_lock) {
+        ESP_EARLY_LOGW(TAG, "lock grabbed");
+    } else {
+        ESP_EARLY_LOGW(TAG, "unable to grab lock");
+    }
+    return self->has_lock;
+}
+
+bool common_hal_busio_i2c_has_lock(busio_i2c_obj_t *self) {
+    return self->has_lock;
+}
+
+void common_hal_busio_i2c_unlock(busio_i2c_obj_t *self) {
+    ESP_EARLY_LOGW(TAG, "unlocking I2C");
+    xSemaphoreGive(self->semaphore_handle);
+    self->has_lock = false;
+}
+
+uint8_t common_hal_busio_i2c_write(busio_i2c_obj_t *self, uint16_t addr,
+                                   const uint8_t *data, size_t len, bool transmit_stop_bit) {
+    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
+    i2c_master_start(cmd);
+    i2c_master_write_byte(cmd, addr << 1, true);
+    i2c_master_write(cmd, (uint8_t*) data, len, true);
+    if (transmit_stop_bit) {
+        i2c_master_stop(cmd);
+    }
+    esp_err_t result = i2c_master_cmd_begin(self->i2c_num, cmd, 100 /* wait in ticks */);
+    i2c_cmd_link_delete(cmd);
+
+    if (result == ESP_OK) {
+        return 0;
+    } else if (result == ESP_FAIL) {
+        return MP_ENODEV;
+    }
+    return MP_EIO;
+}
+
+uint8_t common_hal_busio_i2c_read(busio_i2c_obj_t *self, uint16_t addr,
+        uint8_t *data, size_t len) {
+
+    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
+    i2c_master_start(cmd);
+    i2c_master_write_byte(cmd, addr << 1 | 1, true); // | 1 to indicate read
+    i2c_master_read(cmd, data, len, true);
+    i2c_master_stop(cmd);
+    esp_err_t result = i2c_master_cmd_begin(self->i2c_num, cmd, 100 /* wait in ticks */);
+    i2c_cmd_link_delete(cmd);
+
+    if (result == ESP_OK) {
+        return 0;
+    } else if (result == ESP_FAIL) {
+        return MP_ENODEV;
+    }
+    return MP_EIO;
+}
+
+void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
+    never_reset_i2c(self->i2c_num);
+
+    never_reset_pin(self->scl_pin);
+    never_reset_pin(self->sda_pin);
+}
diff --git a/ports/esp32s2/common-hal/busio/I2C.h b/ports/esp32s2/common-hal/busio/I2C.h
new file mode 100644
index 000000000..d90fb2713
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/I2C.h
@@ -0,0 +1,49 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft
+ *
+ * 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_ESP32S2_COMMON_HAL_BUSIO_I2C_H
+#define MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_I2C_H
+
+#include "common-hal/microcontroller/Pin.h"
+
+#include "esp-idf/components/soc/include/hal/i2c_types.h"
+#include "FreeRTOS.h"
+#include "freertos/semphr.h"
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    const mcu_pin_obj_t* scl_pin;
+    const mcu_pin_obj_t* sda_pin;
+    i2c_port_t i2c_num;
+    StaticSemaphore_t semaphore;
+    SemaphoreHandle_t semaphore_handle;
+    bool has_lock;
+} busio_i2c_obj_t;
+
+void i2c_reset(void);
+
+#endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_BUSIO_I2C_H
diff --git a/ports/esp32s2/common-hal/busio/OneWire.h b/ports/esp32s2/common-hal/busio/OneWire.h
new file mode 100644
index 000000000..bb6a01419
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/OneWire.h
@@ -0,0 +1,33 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2020 Scott Shawcroft
+ *
+ * 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_ESP32S2_COMMON_HAL_BUSIO_ONEWIRE_H
+#define MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_ONEWIRE_H
+
+// Use bitbangio.
+#include "shared-module/busio/OneWire.h"
+
+#endif // MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_ONEWIRE_H
diff --git a/ports/esp32s2/common-hal/busio/SPI.c b/ports/esp32s2/common-hal/busio/SPI.c
new file mode 100644
index 000000000..e761eb49b
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/SPI.c
@@ -0,0 +1,249 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft
+ *
+ * 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/busio/SPI.h"
+#include "py/mperrno.h"
+#include "py/runtime.h"
+
+#include "boards/board.h"
+#include "common-hal/microcontroller/Pin.h"
+#include "supervisor/shared/rgb_led_status.h"
+
+void spi_reset(void) {
+
+}
+
+void common_hal_busio_spi_construct(busio_spi_obj_t *self,
+        const mcu_pin_obj_t * clock, const mcu_pin_obj_t * mosi,
+        const mcu_pin_obj_t * miso) {
+    // uint8_t sercom_index;
+    // uint32_t clock_pinmux = 0;
+    // bool mosi_none = mosi == NULL;
+    // bool miso_none = miso == NULL;
+    // uint32_t mosi_pinmux = 0;
+    // uint32_t miso_pinmux = 0;
+    // uint8_t clock_pad = 0;
+    // uint8_t mosi_pad = 0;
+    // uint8_t miso_pad = 0;
+    // uint8_t dopo = 255;
+
+    // if (sercom == NULL) {
+    //     mp_raise_ValueError(translate("Invalid pins"));
+    // }
+
+    // // Set up SPI clocks on SERCOM.
+    // samd_peripherals_sercom_clock_init(sercom, sercom_index);
+
+    #if defined(MICROPY_HW_APA102_SCK) && defined(MICROPY_HW_APA102_MOSI) && !CIRCUITPY_BITBANG_APA102
+    // // if we're re-using the dotstar sercom, make sure it is disabled or the init will fail out
+    // hri_sercomspi_clear_CTRLA_ENABLE_bit(sercom);
+    #endif
+    // if (spi_m_sync_init(&self->spi_desc, sercom) != ERR_NONE) {
+    //     mp_raise_OSError(MP_EIO);
+    // }
+
+    // Pads must be set after spi_m_sync_init(), which uses default values from
+    // the prototypical SERCOM.
+    // hri_sercomspi_write_CTRLA_DOPO_bf(sercom, dopo);
+    // hri_sercomspi_write_CTRLA_DIPO_bf(sercom, miso_pad);
+
+    // Always start at 250khz which is what SD cards need. They are sensitive to
+    // SPI bus noise before they are put into SPI mode.
+    // uint8_t baud_value = samd_peripherals_spi_baudrate_to_baud_reg_value(250000);
+    // if (spi_m_sync_set_baudrate(&self->spi_desc, baud_value) != ERR_NONE) {
+    //     // spi_m_sync_set_baudrate does not check for validity, just whether the device is
+    //     // busy or not
+    //     mp_raise_OSError(MP_EIO);
+    // }
+
+    // gpio_set_pin_direction(clock->number, GPIO_DIRECTION_OUT);
+    // gpio_set_pin_pull_mode(clock->number, GPIO_PULL_OFF);
+    // gpio_set_pin_function(clock->number, clock_pinmux);
+    // claim_pin(clock);
+    // self->clock_pin = clock->number;
+
+    // if (mosi_none) {
+    //     self->MOSI_pin = NO_PIN;
+    // } else {
+    //     gpio_set_pin_direction(mosi->number, GPIO_DIRECTION_OUT);
+    //     gpio_set_pin_pull_mode(mosi->number, GPIO_PULL_OFF);
+    //     gpio_set_pin_function(mosi->number, mosi_pinmux);
+    //     self->MOSI_pin = mosi->number;
+    //     claim_pin(mosi);
+    // }
+
+    // if (miso_none) {
+    //     self->MISO_pin = NO_PIN;
+    // } else {
+    //     gpio_set_pin_direction(miso->number, GPIO_DIRECTION_IN);
+    //     gpio_set_pin_pull_mode(miso->number, GPIO_PULL_OFF);
+    //     gpio_set_pin_function(miso->number, miso_pinmux);
+    //     self->MISO_pin = miso->number;
+    //     claim_pin(miso);
+    // }
+
+    // spi_m_sync_enable(&self->spi_desc);
+}
+
+void common_hal_busio_spi_never_reset(busio_spi_obj_t *self) {
+    // never_reset_sercom(self->spi_desc.dev.prvt);
+
+    never_reset_pin(self->clock_pin);
+    never_reset_pin(self->MOSI_pin);
+    never_reset_pin(self->MISO_pin);
+}
+
+bool common_hal_busio_spi_deinited(busio_spi_obj_t *self) {
+    return self->clock_pin == NULL;
+}
+
+void common_hal_busio_spi_deinit(busio_spi_obj_t *self) {
+    if (common_hal_busio_spi_deinited(self)) {
+        return;
+    }
+    // allow_reset_sercom(self->spi_desc.dev.prvt);
+
+    // spi_m_sync_disable(&self->spi_desc);
+    // spi_m_sync_deinit(&self->spi_desc);
+    reset_pin(self->clock_pin);
+    reset_pin(self->MOSI_pin);
+    reset_pin(self->MISO_pin);
+    self->clock_pin = NULL;
+}
+
+bool common_hal_busio_spi_configure(busio_spi_obj_t *self,
+        uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t bits) {
+    // If the settings are already what we want then don't reset them.
+    // if (hri_sercomspi_get_CTRLA_CPHA_bit(hw) == phase &&
+    //     hri_sercomspi_get_CTRLA_CPOL_bit(hw) == polarity &&
+    //     hri_sercomspi_read_CTRLB_CHSIZE_bf(hw) == ((uint32_t)bits - 8) &&
+    //     hri_sercomspi_read_BAUD_BAUD_bf(hw) == baud_reg_value) {
+    //     return true;
+    // }
+
+    // Disable, set values (most or all are enable-protected), and re-enable.
+    // spi_m_sync_disable(&self->spi_desc);
+    // hri_sercomspi_wait_for_sync(hw, SERCOM_SPI_SYNCBUSY_MASK);
+
+    // hri_sercomspi_write_CTRLA_CPHA_bit(hw, phase);
+    // hri_sercomspi_write_CTRLA_CPOL_bit(hw, polarity);
+    // hri_sercomspi_write_CTRLB_CHSIZE_bf(hw, bits - 8);
+    // hri_sercomspi_write_BAUD_BAUD_bf(hw, baud_reg_value);
+    // hri_sercomspi_wait_for_sync(hw, SERCOM_SPI_SYNCBUSY_MASK);
+
+    // spi_m_sync_enable(&self->spi_desc);
+    // hri_sercomspi_wait_for_sync(hw, SERCOM_SPI_SYNCBUSY_MASK);
+
+    return true;
+}
+
+bool common_hal_busio_spi_try_lock(busio_spi_obj_t *self) {
+    bool grabbed_lock = false;
+    // CRITICAL_SECTION_ENTER()
+        if (!self->has_lock) {
+            grabbed_lock = true;
+            self->has_lock = true;
+        }
+    // CRITICAL_SECTION_LEAVE();
+    return grabbed_lock;
+}
+
+bool common_hal_busio_spi_has_lock(busio_spi_obj_t *self) {
+    return self->has_lock;
+}
+
+void common_hal_busio_spi_unlock(busio_spi_obj_t *self) {
+    self->has_lock = false;
+}
+
+bool common_hal_busio_spi_write(busio_spi_obj_t *self,
+        const uint8_t *data, size_t len) {
+    if (len == 0) {
+        return true;
+    }
+    // int32_t status;
+    if (len >= 16) {
+        // status = sercom_dma_write(self->spi_desc.dev.prvt, data, len);
+    } else {
+        // struct io_descriptor *spi_io;
+        // spi_m_sync_get_io_descriptor(&self->spi_desc, &spi_io);
+        // status = spi_io->write(spi_io, data, len);
+    }
+    return false; // Status is number of chars read or an error code < 0.
+}
+
+bool common_hal_busio_spi_read(busio_spi_obj_t *self,
+        uint8_t *data, size_t len, uint8_t write_value) {
+    if (len == 0) {
+        return true;
+    }
+    // int32_t status;
+    if (len >= 16) {
+        // status = sercom_dma_read(self->spi_desc.dev.prvt, data, len, write_value);
+    } else {
+        // self->spi_desc.dev.dummy_byte = write_value;
+
+        // struct io_descriptor *spi_io;
+        // spi_m_sync_get_io_descriptor(&self->spi_desc, &spi_io);
+
+        // status = spi_io->read(spi_io, data, len);
+    }
+    return false; // Status is number of chars read or an error code < 0.
+}
+
+bool common_hal_busio_spi_transfer(busio_spi_obj_t *self, uint8_t *data_out, uint8_t *data_in, size_t len) {
+    if (len == 0) {
+        return true;
+    }
+    // int32_t status;
+    if (len >= 16) {
+        // status = sercom_dma_transfer(self->spi_desc.dev.prvt, data_out, data_in, len);
+    } else {
+        // struct spi_xfer xfer;
+        // xfer.txbuf = data_out;
+        // xfer.rxbuf = data_in;
+        // xfer.size = len;
+        // status = spi_m_sync_transfer(&self->spi_desc, &xfer);
+    }
+    return false; // Status is number of chars read or an error code < 0.
+}
+
+uint32_t common_hal_busio_spi_get_frequency(busio_spi_obj_t* self) {
+    // return samd_peripherals_spi_baud_reg_value_to_baudrate(hri_sercomspi_read_BAUD_reg(self->spi_desc.dev.prvt));
+    return 0;
+}
+
+uint8_t common_hal_busio_spi_get_phase(busio_spi_obj_t* self) {
+    // void * hw = self->spi_desc.dev.prvt;
+    // return hri_sercomspi_get_CTRLA_CPHA_bit(hw);
+    return 0;
+}
+
+uint8_t common_hal_busio_spi_get_polarity(busio_spi_obj_t* self) {
+    // void * hw = self->spi_desc.dev.prvt;
+    // return hri_sercomspi_get_CTRLA_CPOL_bit(hw);
+    return 0;
+}
diff --git a/ports/esp32s2/common-hal/busio/SPI.h b/ports/esp32s2/common-hal/busio/SPI.h
new file mode 100644
index 000000000..0ff1a4f7e
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/SPI.h
@@ -0,0 +1,44 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft
+ *
+ * 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_ESP32S2_COMMON_HAL_BUSIO_SPI_H
+#define MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_SPI_H
+
+#include "common-hal/microcontroller/Pin.h"
+
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    bool has_lock;
+    const mcu_pin_obj_t* clock_pin;
+    const mcu_pin_obj_t* MOSI_pin;
+    const mcu_pin_obj_t* MISO_pin;
+} busio_spi_obj_t;
+
+void spi_reset(void);
+
+#endif // MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_SPI_H
diff --git a/ports/esp32s2/common-hal/busio/UART.c b/ports/esp32s2/common-hal/busio/UART.c
new file mode 100644
index 000000000..4a016ad1a
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/UART.c
@@ -0,0 +1,405 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * 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/microcontroller/__init__.h"
+#include "shared-bindings/busio/UART.h"
+
+#include "mpconfigport.h"
+#include "lib/utils/interrupt_char.h"
+#include "py/gc.h"
+#include "py/mperrno.h"
+#include "py/runtime.h"
+#include "py/stream.h"
+#include "supervisor/shared/translate.h"
+#include "supervisor/shared/tick.h"
+
+#define UART_DEBUG(...) (void)0
+// #define UART_DEBUG(...) mp_printf(&mp_plat_print __VA_OPT__(,) __VA_ARGS__)
+
+// Do-nothing callback needed so that usart_async code will enable rx interrupts.
+// See comment below re usart_async_register_callback()
+// static void usart_async_rxc_callback(const struct usart_async_descriptor *const descr) {
+//     // Nothing needs to be done by us.
+// }
+
+void uart_reset(void) {
+
+}
+
+void common_hal_busio_uart_construct(busio_uart_obj_t *self,
+    const mcu_pin_obj_t * tx, const mcu_pin_obj_t * rx,
+    const mcu_pin_obj_t * rts, const mcu_pin_obj_t * cts,
+    const mcu_pin_obj_t * rs485_dir, bool rs485_invert,
+    uint32_t baudrate, uint8_t bits, uart_parity_t parity, uint8_t stop,
+    mp_float_t timeout, uint16_t receiver_buffer_size, byte* receiver_buffer,
+    bool sigint_enabled) {
+
+    // uint8_t sercom_index = 255; // Unset index
+    // uint32_t rx_pinmux = 0;
+    // uint8_t rx_pad = 255; // Unset pad
+    // uint32_t tx_pinmux = 0;
+    // uint8_t tx_pad = 255; // Unset pad
+
+    // if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
+    //     mp_raise_ValueError(translate("RTS/CTS/RS485 Not yet supported on this device"));
+    // }
+
+    // if (bits > 8) {
+    //     mp_raise_NotImplementedError(translate("bytes > 8 bits not supported"));
+    // }
+
+    bool have_tx = tx != NULL;
+    bool have_rx = rx != NULL;
+    if (!have_tx && !have_rx) {
+        mp_raise_ValueError(translate("tx and rx cannot both be None"));
+    }
+
+    self->baudrate = baudrate;
+    self->character_bits = bits;
+    self->timeout_ms = timeout * 1000;
+
+    // This assignment is only here because the usart_async routines take a *const argument.
+//     struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+
+//     for (int i = 0; i < NUM_SERCOMS_PER_PIN; i++) {
+//         Sercom* potential_sercom = NULL;
+//         if (have_tx) {
+//             sercom_index = tx->sercom[i].index;
+//             if (sercom_index >= SERCOM_INST_NUM) {
+//                 continue;
+//             }
+//             potential_sercom = sercom_insts[sercom_index];
+// #ifdef SAMD21
+// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
+//                 !(tx->sercom[i].pad == 0 ||
+//                   tx->sercom[i].pad == 2)) {
+//                 continue;
+//             }
+// #endif
+// #ifdef SAMD51
+// 	    if (potential_sercom->USART.CTRLA.bit.ENABLE != 0 ||
+//                 !(tx->sercom[i].pad == 0)) {
+//                 continue;
+//             }
+// #endif
+//             tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
+//             tx_pad = tx->sercom[i].pad;
+//             if (rx == NULL) {
+//                 sercom = potential_sercom;
+//                 break;
+//             }
+//         }
+//         for (int j = 0; j < NUM_SERCOMS_PER_PIN; j++) {
+//             if (((!have_tx && rx->sercom[j].index < SERCOM_INST_NUM &&
+//                   sercom_insts[rx->sercom[j].index]->USART.CTRLA.bit.ENABLE == 0) ||
+//                  sercom_index == rx->sercom[j].index) &&
+//                 rx->sercom[j].pad != tx_pad) {
+//                 rx_pinmux = PINMUX(rx->number, (j == 0) ? MUX_C : MUX_D);
+//                 rx_pad = rx->sercom[j].pad;
+//                 sercom = sercom_insts[rx->sercom[j].index];
+//                 sercom_index = rx->sercom[j].index;
+//                 break;
+//             }
+//         }
+//         if (sercom != NULL) {
+//             break;
+//         }
+//     }
+    // if (sercom == NULL) {
+    //     mp_raise_ValueError(translate("Invalid pins"));
+    // }
+    // if (!have_tx) {
+    //     tx_pad = 0;
+    //     if (rx_pad == 0) {
+    //         tx_pad = 2;
+    //     }
+    // }
+    // if (!have_rx) {
+    //     rx_pad = (tx_pad + 1) % 4;
+    // }
+
+    // // Set up clocks on SERCOM.
+    // samd_peripherals_sercom_clock_init(sercom, sercom_index);
+
+    // if (rx && receiver_buffer_size > 0) {
+    //     self->buffer_length = receiver_buffer_size;
+    //     // Initially allocate the UART's buffer in the long-lived part of the
+    //     // heap.  UARTs are generally long-lived objects, but the "make long-
+    //     // lived" machinery is incapable of moving internal pointers like
+    //     // self->buffer, so do it manually.  (However, as long as internal
+    //     // pointers like this are NOT moved, allocating the buffer
+    //     // in the long-lived pool is not strictly necessary)
+    //     self->buffer = (uint8_t *) gc_alloc(self->buffer_length * sizeof(uint8_t), false, true);
+    //     if (self->buffer == NULL) {
+    //         common_hal_busio_uart_deinit(self);
+    //         mp_raise_msg_varg(&mp_type_MemoryError, translate("Failed to allocate RX buffer of %d bytes"), self->buffer_length * sizeof(uint8_t));
+    //     }
+    // } else {
+    //     self->buffer_length = 0;
+    //     self->buffer = NULL;
+    // }
+
+    // if (usart_async_init(usart_desc_p, sercom, self->buffer, self->buffer_length, NULL) != ERR_NONE) {
+    //     mp_raise_ValueError(translate("Could not initialize UART"));
+    // }
+
+    // usart_async_init() sets a number of defaults based on a prototypical SERCOM
+    // which don't necessarily match what we need. After calling it, set the values
+    // specific to this instantiation of UART.
+
+    // Set pads computed for this SERCOM.
+    // TXPO:
+    // 0x0: TX pad 0; no RTS/CTS
+    // 0x1: TX pad 2; no RTS/CTS
+    // 0x2: TX pad 0; RTS: pad 2, CTS: pad 3 (not used by us right now)
+    // So divide by 2 to map pad to value.
+    // RXPO:
+    // 0x0: RX pad 0
+    // 0x1: RX pad 1
+    // 0x2: RX pad 2
+    // 0x3: RX pad 3
+
+    // Doing a group mask and set of the registers saves 60 bytes over setting the bitfields individually.
+
+    // sercom->USART.CTRLA.reg &= ~(SERCOM_USART_CTRLA_TXPO_Msk |
+    //                              SERCOM_USART_CTRLA_RXPO_Msk |
+    //                              SERCOM_USART_CTRLA_FORM_Msk);
+    // sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(tx_pad / 2) |
+    //                            SERCOM_USART_CTRLA_RXPO(rx_pad) |
+    //                            (parity == PARITY_NONE ? 0 : SERCOM_USART_CTRLA_FORM(1));
+
+    // Enable tx and/or rx based on whether the pins were specified.
+    // CHSIZE is 0 for 8 bits, 5, 6, 7 for 5, 6, 7 bits. 1 for 9 bits, but we don't support that.
+    // sercom->USART.CTRLB.reg &= ~(SERCOM_USART_CTRLB_TXEN |
+    //                              SERCOM_USART_CTRLB_RXEN |
+    //                              SERCOM_USART_CTRLB_PMODE |
+    //                              SERCOM_USART_CTRLB_SBMODE |
+    //                              SERCOM_USART_CTRLB_CHSIZE_Msk);
+    // sercom->USART.CTRLB.reg |= (have_tx ? SERCOM_USART_CTRLB_TXEN : 0) |
+    //                            (have_rx ? SERCOM_USART_CTRLB_RXEN : 0) |
+    //                            (parity == PARITY_ODD ? SERCOM_USART_CTRLB_PMODE : 0) |
+    //                            (stop > 1 ? SERCOM_USART_CTRLB_SBMODE : 0) |
+    //                            SERCOM_USART_CTRLB_CHSIZE(bits % 8);
+
+    // Set baud rate
+    // common_hal_busio_uart_set_baudrate(self, baudrate);
+
+    // Turn on rx interrupt handling. The UART async driver has its own set of internal callbacks,
+    // which are set up by uart_async_init(). These in turn can call user-specified callbacks.
+    // In fact, the actual interrupts are not enabled unless we set up a user-specified callback.
+    // This is confusing. It's explained in the Atmel START User Guide -> Implementation Description ->
+    // Different read function behavior in some asynchronous drivers. As of this writing:
+    // http://start.atmel.com/static/help/index.html?GUID-79201A5A-226F-4FBB-B0B8-AB0BE0554836
+    // Look at the ASFv4 code example for async USART.
+    // usart_async_register_callback(usart_desc_p, USART_ASYNC_RXC_CB, usart_async_rxc_callback);
+
+
+    // if (have_tx) {
+    //     gpio_set_pin_direction(tx->number, GPIO_DIRECTION_OUT);
+    //     gpio_set_pin_pull_mode(tx->number, GPIO_PULL_OFF);
+    //     gpio_set_pin_function(tx->number, tx_pinmux);
+    //     self->tx_pin  = tx->number;
+    //     claim_pin(tx);
+    // } else {
+    //     self->tx_pin = NO_PIN;
+    // }
+
+    // if (have_rx) {
+    //     gpio_set_pin_direction(rx->number, GPIO_DIRECTION_IN);
+    //     gpio_set_pin_pull_mode(rx->number, GPIO_PULL_OFF);
+    //     gpio_set_pin_function(rx->number, rx_pinmux);
+    //     self->rx_pin  = rx->number;
+    //     claim_pin(rx);
+    // } else {
+    //     self->rx_pin = NO_PIN;
+    // }
+
+    // usart_async_enable(usart_desc_p);
+}
+
+bool common_hal_busio_uart_deinited(busio_uart_obj_t *self) {
+    return self->rx_pin == NULL && self->tx_pin == NULL;
+}
+
+void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
+    if (common_hal_busio_uart_deinited(self)) {
+        return;
+    }
+    // // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+    // usart_async_disable(usart_desc_p);
+    // usart_async_deinit(usart_desc_p);
+    reset_pin(self->rx_pin);
+    reset_pin(self->tx_pin);
+    self->rx_pin = NULL;
+    self->tx_pin = NULL;
+}
+
+// Read characters.
+size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t len, int *errcode) {
+    if (self->rx_pin == NULL) {
+        mp_raise_ValueError(translate("No RX pin"));
+    }
+
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+
+    if (len == 0) {
+        // Nothing to read.
+        return 0;
+    }
+
+    // struct io_descriptor *io;
+    // usart_async_get_io_descriptor(usart_desc_p, &io);
+
+    // size_t total_read = 0;
+    // uint64_t start_ticks = supervisor_ticks_ms64();
+
+    // Busy-wait until timeout or until we've read enough chars.
+    // while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
+    //     // Read as many chars as we can right now, up to len.
+    //     size_t num_read = io_read(io, data, len);
+
+    //     // Advance pointer in data buffer, and decrease how many chars left to read.
+    //     data += num_read;
+    //     len -= num_read;
+    //     total_read += num_read;
+    //     if (len == 0) {
+    //         // Don't need to read any more: data buf is full.
+    //         break;
+    //     }
+    //     if (num_read > 0) {
+    //         // Reset the timeout on every character read.
+    //         start_ticks = supervisor_ticks_ms64();
+    //     }
+    //     RUN_BACKGROUND_TASKS;
+    //     // Allow user to break out of a timeout with a KeyboardInterrupt.
+    //     if (mp_hal_is_interrupted()) {
+    //         break;
+    //     }
+    //     // If we are zero timeout, make sure we don't loop again (in the event
+    //     // we read in under 1ms)
+    //     if (self->timeout_ms == 0) {
+    //         break;
+    //     }
+    // }
+
+    // if (total_read == 0) {
+    //     *errcode = EAGAIN;
+    //     return MP_STREAM_ERROR;
+    // }
+
+    // return total_read;
+    return 0;
+}
+
+// Write characters.
+size_t common_hal_busio_uart_write(busio_uart_obj_t *self, const uint8_t *data, size_t len, int *errcode) {
+    if (self->tx_pin == NULL) {
+        mp_raise_ValueError(translate("No TX pin"));
+    }
+
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+
+    // struct io_descriptor *io;
+    // usart_async_get_io_descriptor(usart_desc_p, &io);
+
+    // // Start writing characters. This is non-blocking and will
+    // // return immediately after setting up the write.
+    // if (io_write(io, data, len) < 0) {
+    //     *errcode = MP_EAGAIN;
+    //     return MP_STREAM_ERROR;
+    // }
+
+    // // Busy-wait until all characters transmitted.
+    // struct usart_async_status async_status;
+    // while (true) {
+    //     usart_async_get_status(usart_desc_p, &async_status);
+    //     if (async_status.txcnt >= len) {
+    //         break;
+    //     }
+    //     RUN_BACKGROUND_TASKS;
+    // }
+
+    return len;
+}
+
+uint32_t common_hal_busio_uart_get_baudrate(busio_uart_obj_t *self) {
+    return self->baudrate;
+}
+
+void common_hal_busio_uart_set_baudrate(busio_uart_obj_t *self, uint32_t baudrate) {
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+    // usart_async_set_baud_rate(usart_desc_p,
+    //                           // Samples and ARITHMETIC vs FRACTIONAL must correspond to USART_SAMPR in
+    //                           // hpl_sercom_config.h.
+    //                           _usart_async_calculate_baud_rate(baudrate,  // e.g. 9600 baud
+    //                                                            PROTOTYPE_SERCOM_USART_ASYNC_CLOCK_FREQUENCY,
+    //                                                            16,   // samples
+    //                                                            USART_BAUDRATE_ASYNCH_ARITHMETIC,
+    //                                                            0  // fraction - not used for ARITHMETIC
+    //                                                            ));
+    self->baudrate = baudrate;
+}
+
+mp_float_t common_hal_busio_uart_get_timeout(busio_uart_obj_t *self) {
+    return (mp_float_t) (self->timeout_ms / 1000.0f);
+}
+
+void common_hal_busio_uart_set_timeout(busio_uart_obj_t *self, mp_float_t timeout) {
+    self->timeout_ms = timeout * 1000;
+}
+
+uint32_t common_hal_busio_uart_rx_characters_available(busio_uart_obj_t *self) {
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+    // struct usart_async_status async_status;
+    // usart_async_get_status(usart_desc_p, &async_status);
+    // return async_status.rxcnt;
+    return 0;
+}
+
+void common_hal_busio_uart_clear_rx_buffer(busio_uart_obj_t *self) {
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+    // usart_async_flush_rx_buffer(usart_desc_p);
+
+}
+
+// True if there are no characters still to be written.
+bool common_hal_busio_uart_ready_to_tx(busio_uart_obj_t *self) {
+    if (self->tx_pin == NULL) {
+        return false;
+    }
+    // This assignment is only here because the usart_async routines take a *const argument.
+    // struct usart_async_descriptor * const usart_desc_p = (struct usart_async_descriptor * const) &self->usart_desc;
+    // struct usart_async_status async_status;
+    // usart_async_get_status(usart_desc_p, &async_status);
+    // return !(async_status.flags & USART_ASYNC_STATUS_BUSY);
+    return false;
+}
diff --git a/ports/esp32s2/common-hal/busio/UART.h b/ports/esp32s2/common-hal/busio/UART.h
new file mode 100644
index 000000000..3c2bd1dac
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/UART.h
@@ -0,0 +1,48 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Scott Shawcroft
+ *
+ * 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_ESP32S2_COMMON_HAL_BUSIO_UART_H
+#define MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_UART_H
+
+#include "common-hal/microcontroller/Pin.h"
+
+#include "py/obj.h"
+
+typedef struct {
+    mp_obj_base_t base;
+    const mcu_pin_obj_t* rx_pin;
+    const mcu_pin_obj_t* tx_pin;
+    uint8_t character_bits;
+    bool rx_error;
+    uint32_t baudrate;
+    uint32_t timeout_ms;
+    uint32_t buffer_length;
+    uint8_t* buffer;
+} busio_uart_obj_t;
+
+void uart_reset(void);
+
+#endif // MICROPY_INCLUDED_ESP32S2_COMMON_HAL_BUSIO_UART_H
diff --git a/ports/esp32s2/common-hal/busio/__init__.c b/ports/esp32s2/common-hal/busio/__init__.c
new file mode 100644
index 000000000..41761b674
--- /dev/null
+++ b/ports/esp32s2/common-hal/busio/__init__.c
@@ -0,0 +1 @@
+// No busio module functions.
diff --git a/ports/esp32s2/common-hal/microcontroller/Pin.c b/ports/esp32s2/common-hal/microcontroller/Pin.c
index 4c39eea16..fd815518d 100644
--- a/ports/esp32s2/common-hal/microcontroller/Pin.c
+++ b/ports/esp32s2/common-hal/microcontroller/Pin.c
@@ -49,6 +49,10 @@ void reset_pin_number(gpio_num_t pin_number) {
     in_use[pin_number / 32] &= ~(1 << pin_number % 32);
 }
 
+void reset_pin(const mcu_pin_obj_t* pin) {
+    reset_pin_number(pin->number);
+}
+
 void reset_all_pins(void) {
     for (uint8_t i = 0; i < GPIO_PIN_COUNT; i++) {
         uint32_t iomux_address = GPIO_PIN_MUX_REG[i];
diff --git a/ports/esp32s2/common-hal/microcontroller/Pin.h b/ports/esp32s2/common-hal/microcontroller/Pin.h
index 6f47b1ed3..573eec392 100644
--- a/ports/esp32s2/common-hal/microcontroller/Pin.h
+++ b/ports/esp32s2/common-hal/microcontroller/Pin.h
@@ -35,6 +35,7 @@ void reset_all_pins(void);
 // reset_pin_number takes the pin number instead of the pointer so that objects don't
 // need to store a full pointer.
 void reset_pin_number(gpio_num_t pin_number);
+void reset_pin(const mcu_pin_obj_t* pin);
 void claim_pin(const mcu_pin_obj_t* pin);
 bool pin_number_is_free(gpio_num_t pin_number);
 void never_reset_pin_number(gpio_num_t pin_number);
diff --git a/ports/esp32s2/mpconfigport.mk b/ports/esp32s2/mpconfigport.mk
index c9df81db0..9f59c1b46 100644
--- a/ports/esp32s2/mpconfigport.mk
+++ b/ports/esp32s2/mpconfigport.mk
@@ -16,10 +16,10 @@ CIRCUITPY_FULL_BUILD = 0
 CIRCUITPY_ANALOGIO = 0
 CIRCUITPY_AUDIOBUSIO = 0
 CIRCUITPY_AUDIOIO = 0
-CIRCUITPY_BITBANGIO = 0
+CIRCUITPY_BITBANGIO = 1
 CIRCUITPY_BOARD = 1
 CIRCUITPY_DIGITALIO = 1
-CIRCUITPY_BUSIO = 0
+CIRCUITPY_BUSIO = 1
 CIRCUITPY_DISPLAYIO = 0
 CIRCUITPY_FREQUENCYIO = 0
 CIRCUITPY_I2CSLAVE = 0
diff --git a/ports/esp32s2/supervisor/port.c b/ports/esp32s2/supervisor/port.c
index 2437b4f34..fbfbc9f2e 100644
--- a/ports/esp32s2/supervisor/port.c
+++ b/ports/esp32s2/supervisor/port.c
@@ -35,6 +35,9 @@
 #include "freertos/task.h"
 
 #include "common-hal/microcontroller/Pin.h"
+#include "common-hal/busio/I2C.h"
+#include "common-hal/busio/SPI.h"
+#include "common-hal/busio/UART.h"
 #include "supervisor/memory.h"
 #include "supervisor/shared/tick.h"
 
@@ -64,8 +67,13 @@ safe_mode_t port_init(void) {
 }
 
 void reset_port(void) {
-
     reset_all_pins();
+
+#if CIRCUITPY_BUSIO
+    i2c_reset();
+    spi_reset();
+    uart_reset();
+#endif
 }
 
 void reset_to_bootloader(void) {