diff options
Diffstat (limited to 'ports')
| -rw-r--r-- | ports/esp32s2/common-hal/displayio/ParallelBus.c | 90 |
1 files changed, 39 insertions, 51 deletions
diff --git a/ports/esp32s2/common-hal/displayio/ParallelBus.c b/ports/esp32s2/common-hal/displayio/ParallelBus.c index 04e24b291..b644610f2 100644 --- a/ports/esp32s2/common-hal/displayio/ParallelBus.c +++ b/ports/esp32s2/common-hal/displayio/ParallelBus.c @@ -34,20 +34,18 @@ #include "shared-bindings/microcontroller/__init__.h" /* -* Current pin limitations: -* data0 pin must be byte aligned and use pin numbers < 32 (data0 options: 0, 8, 16 or 24) -* write pin must be pin number < 32. -* -* Future extensions: -* 1. Allow data0 pin numbers >= 32. -* 2. Allow write pin numbers >= 32. -*/ + * + * Current pin limitations for ESP32-S2 ParallelBus: + * 1. data0 pin must be byte aligned (data0 pin options: 0, 8, 16 or 24) + * 2. The 8 data lines must use pin numbers < 32 + * 3. The write pin must be pin number < 32. + * + */ void common_hal_displayio_parallelbus_construct(displayio_parallelbus_obj_t* self, const mcu_pin_obj_t* data0, const mcu_pin_obj_t* command, const mcu_pin_obj_t* chip_select, const mcu_pin_obj_t* write, const mcu_pin_obj_t* read, const mcu_pin_obj_t* reset) { - uint8_t data_pin = data0->number; if ( (data_pin % 8 != 0) && (data_pin >= 32) ) { mp_raise_ValueError(translate("Data 0 pin must be byte aligned and < 32")); @@ -63,10 +61,10 @@ void common_hal_displayio_parallelbus_construct(displayio_parallelbus_obj_t* sel mp_raise_ValueError(translate("Write pin must be < 32")); } - gpio_dev_t *g = &GPIO; /* this is the GPIO registers, see "extern gpio_dev_t GPIO" from file:gpio_struct.h */ + gpio_dev_t *g = &GPIO; // this is the GPIO registers, see "extern gpio_dev_t GPIO" from file:gpio_struct.h - /* Setup the pins as "Simple GPIO outputs" see section 19.3.3 of the ESP32-S2 Reference Manual */ - /* Enable pins with "enable_w1ts" */ + // Setup the pins as "Simple GPIO outputs" see section 19.3.3 of the ESP32-S2 Reference Manual + // Enable pins with "enable_w1ts" for (uint8_t i = 0; i < 8; i++) { g->enable_w1ts = (0x1 << (data_pin + i)); @@ -74,10 +72,11 @@ void common_hal_displayio_parallelbus_construct(displayio_parallelbus_obj_t* sel } - /* I think there is a limitation of the ESP32-S2 that does not allow single-byte writes into - the GPIO registers. See section 10.3.3 regarding "non-aligned writes" into the registers. - If a method for writing single-byte writes is uncovered, this code can be modified to provide - single-byte access into the output register */ + /* From my understanding, there is a limitation of the ESP32-S2 that does not allow single-byte writes + * into the GPIO registers. See section 10.3.3 regarding "non-aligned writes" into the registers. + * If a method for writing single-byte writes is uncovered, this code can be modified to provide + * single-byte access into the output register + */ self->bus = (uint32_t*) &g->out; //pointer to GPIO output register (for pins 0-31) @@ -100,14 +99,16 @@ void common_hal_displayio_parallelbus_construct(displayio_parallelbus_obj_t* sel self->data0_pin = data_pin; self->write_group = &GPIO; - /* Should modify the .h structure definitions if want to allow a write pin >= 32. - If so, consider putting separate "clear_write" and "set_write" pointers into the .h in place of "write_group" - to select between out_w1tc/out1_w1tc (clear) and out_w1ts/out1_w1ts (set) registers. */ + /* If we want to allow a write pin >= 32, should consider putting separate "clear_write" and + * "set_write" pointers into the .h in place of "write_group" + * to select between out_w1tc/out1_w1tc (clear) and out_w1ts/out1_w1ts (set) registers. + */ self->write_mask = 1 << (write->number % 32); /* the write pin triggers the LCD to latch the data */ /* Note: As currently written for the ESP32-S2 port, the write pin must be a pin number less than 32 - This could be updated to accommodate 32 and higher by using the different construction of the - address for writing to output pins >= 32, see related note above for 'self->write_group' */ + * This could be updated to accommodate 32 and higher by using the different construction of the + * address for writing to output pins >= 32, see related note above for 'self->write_group' + */ /* SNIP - common setup of the reset pin, same as from SAMD and NRF ports */ self->reset.base.type = &mp_type_NoneType; @@ -174,57 +175,44 @@ void common_hal_displayio_parallelbus_send(mp_obj_t obj, display_byte_type_t byt common_hal_digitalio_digitalinout_set_value(&self->command, byte_type == DISPLAY_DATA); /* Currently the write pin number must be < 32. - Future: To accommodate write pin numbers >= 32, will need to update to choose a different register - for set/reset (out1_w1tc and out1_w1ts) */ - - // **** Bit shifting trial - // uint32_t* output_register = self->bus; - // const uint8_t bit_shift=self->data0_pin; + * Future: To accommodate write pin numbers >= 32, will need to update to choose the correct register + * for the write pin set/clear (out_w1ts/out1_w1ts and out_w1tc/out1_w1tc) + */ uint32_t* clear_write = (uint32_t*) &self->write_group->out_w1tc; uint32_t* set_write = (uint32_t*) &self->write_group->out_w1ts; const uint32_t mask = self->write_mask; - /* Setup structures for data writing. The ESP32-S2 port differs from the SAMD and NRF ports - because I have not found a way to write a single byte into the ESP32-S2 registers. - For the ESP32-S2, I create a 32-bit data_buffer that is used to transfer the data bytes. */ + * because I have not found a way to write a single byte into the ESP32-S2 registers. + * For the ESP32-S2, I create a 32-bit data_buffer that is used to transfer the data bytes. + */ - *clear_write = mask; // Clear the write pin to prepare the registers before storing register settings into data_buffer + *clear_write = mask; // Clear the write pin to prepare the registers before storing the + // register value into data_buffer const uint32_t data_buffer = *self->bus; // store the initial output register values into the data output buffer uint8_t* data_address = ((uint8_t*) &data_buffer) + (self->data0_pin / 8); /* address inside data_buffer where - each data byte will be written (as offset by (data0_pin/8) number of bytes) */ - - // *** Bit shifting trial - // *data_address = 0; //clear the 8 data bits - - //mp_printf(&mp_plat_print, "\n\ndata_buffer: %x\n", data_buffer); - //mp_printf(&mp_plat_print, "data[0]: %x\n", data[0]); - //mp_printf(&mp_plat_print, "data_buffer[0]: %x\n\n", (data_buffer | (((uint32_t) data[0]) << self->data0_pin))); + * each data byte will be written to the data pin registers + */ for (uint32_t i = 0; i < data_length; i++) { /* Question: Is there a faster way of stuffing the data byte into the data_buffer, is bit arithmetic - faster than writing to the byte address? */ + * faster than writing to the byte address? + */ - /* Note: May be able to eliminate either the clear_write or set_write since the data buffer - can be written with the write pin cleared or set already, and depending upon whether the display - latches the data on the rising or falling edge of the write pin. Remember: This method - will require the write pin to be controlled by the same GPIO register as the data pins. */ + /* Note: If the write pin and data pins are controlled by the same GPIO register, we can eliminate + * the "clear_write" step below, since the write pin is cleared when the data_buffer is written + * to the bus. + * Remember: This method requires the write pin to be controlled by the same GPIO register as the data pins. + */ - // Can ignore this line if the write pin is in the same register as the data pins // *clear_write = mask; // clear the write pin (See comment above, this may not be necessary). - // *** Original code *(data_address) = data[i]; // stuff the data byte into the data_buffer at the correct offset byte location *self->bus = data_buffer; // write the data to the output register - - // *** Bit shifting trial - didn't have much improvement in performance - // *output_register = (data_buffer | (((uint32_t) data[i]) << bit_shift)); - - *set_write = mask; // set the write pin } |