a61e51f579
Co-authored-by: Zoltan Janosy <zjanosy@fishman.com> Co-authored-by: Gabor Kiss-Vamosi <kisvegabor@gmail.com>
110 lines
4.4 KiB
ReStructuredText
110 lines
4.4 KiB
ReStructuredText
==================================================================================================
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LCD driver SPI bus I/O implementation example for STM32 devices using the STM32Cube HAL SPI driver
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==================================================================================================
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This is an example implementation of an SPI bus driver using STM32CubeIDE and the ST HAL libraries, tested on a Nucleo-F746ZG board. This code example only implements
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the LCD driver specific parts, so you still have to configure the hardware using STM32CubeMX or STM32CubeIDE. It is not meant as the best possible implementation,
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but since it uses DMA for the pixel transfer, it has a good performance.
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To use this code without change you need to name the appropriate GPIO pins as follows:
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.. code:: c
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LCD_RESET /* Reset */
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LCD_CS /* Chip Select */
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LCD_DCX /* Data/Command Select */
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The example code uses the SPI1 port. The SPI controller of the STM32F746 is capable of 16-bit transfers, and it can swap the 16-bit pixel data bytes on the fly, so
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there is no need to do this in software. This improves the performance considerably.
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This code implements a rather simple locking mechanism using a global variable :cpp:var:`my_disp_bus_busy` to prevent accessing the controller while there is a DMA transfer
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going on in the background. In a more sophisticated implementation this could be replaced with a semaphore or a transaction queue.
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.. code:: c
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#include "stm32f7xx_hal.h"
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#include "lvgl.h"
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...
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lv_display_t *my_disp;
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volatile int my_disp_bus_busy = 0;
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...
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/* DMA transfer ready callback */
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static void my_lcd_color_transfer_ready_cb(SPI_HandleTypeDef *hspi)
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{
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/* CS high */
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HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
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my_disp_bus_busy = 0;
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lv_display_flush_ready(my_disp);
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}
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/* Initialize LCD I/O bus, reset LCD */
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static int32_t my_lcd_io_init(void)
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{
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/* Register SPI Tx Complete Callback */
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HAL_SPI_RegisterCallback(&hspi1, HAL_SPI_TX_COMPLETE_CB_ID, stm32_lcd_color_transfer_ready_cb);
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/* reset LCD */
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HAL_GPIO_WritePin(LCD_RESET_GPIO_Port, LCD_RESET_Pin, GPIO_PIN_RESET);
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HAL_Delay(100);
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HAL_GPIO_WritePin(LCD_RESET_GPIO_Port, LCD_RESET_Pin, GPIO_PIN_SET);
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HAL_Delay(100);
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HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
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HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
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return HAL_OK;
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}
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/* Send short command to the LCD. This function shall wait until the transaction finishes. */
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static void my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
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{
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LV_UNUSED(disp);
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/* Set the SPI in 8-bit mode */
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hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
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HAL_SPI_Init(&hspi1);
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/* DCX low (command) */
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HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_RESET);
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/* CS low */
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HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_RESET);
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/* send command */
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if (HAL_SPI_Transmit(&hspi1, cmd, cmd_size, BUS_SPI1_POLL_TIMEOUT) == HAL_OK) {
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/* DCX high (data) */
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HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
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/* for short data blocks we use polling transfer */
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HAL_SPI_Transmit(&hspi1, (uint8_t *)param, (uint16_t)param_size, BUS_SPI1_POLL_TIMEOUT);
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/* CS high */
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HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
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}
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}
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/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
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static void my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
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{
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LV_UNUSED(disp);
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while (my_disp_bus_busy); /* wait until previous transfer is finished */
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/* Set the SPI in 8-bit mode */
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hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
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HAL_SPI_Init(&hspi1);
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/* DCX low (command) */
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HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_RESET);
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/* CS low */
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HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_RESET);
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/* send command */
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if (HAL_SPI_Transmit(&hspi1, cmd, cmd_size, BUS_SPI1_POLL_TIMEOUT) == HAL_OK) {
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/* DCX high (data) */
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HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
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/* for color data use DMA transfer */
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/* Set the SPI in 16-bit mode to match endianess */
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hspi1.Init.DataSize = SPI_DATASIZE_16BIT;
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HAL_SPI_Init(&hspi1);
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my_disp_bus_busy = 1;
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HAL_SPI_Transmit_DMA(&hspi1, param, (uint16_t)param_size / 2);
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/* NOTE: CS will be reset in the transfer ready callback */
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}
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}
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