ili9341_touch.c

/*
 * ili9341_touch.c
 *
 *  Created on: 29 mars 2023
 *      Author: PC-MAGH
 */


#include "stm32f1xx_hal.h"
#include "ili9341_touch.h"

#define READ_X 0xD0
#define READ_Y 0x90

static void ILI9341_TouchSelect() {
    HAL_GPIO_WritePin(ILI9341_TOUCH_CS_GPIO_Port, ILI9341_TOUCH_CS_Pin, GPIO_PIN_RESET);
}

void ILI9341_TouchUnselect() {
    HAL_GPIO_WritePin(ILI9341_TOUCH_CS_GPIO_Port, ILI9341_TOUCH_CS_Pin, GPIO_PIN_SET);
}

bool ILI9341_TouchPressed() {
    return HAL_GPIO_ReadPin(ILI9341_TOUCH_IRQ_GPIO_Port, ILI9341_TOUCH_IRQ_Pin) == GPIO_PIN_RESET;
}

bool ILI9341_TouchGetCoordinates(uint16_t* x, uint16_t* y) {
    static const uint8_t cmd_read_x[] = { READ_X };
    static const uint8_t cmd_read_y[] = { READ_Y };
    static const uint8_t zeroes_tx[] = { 0x00, 0x00 };

    ILI9341_TouchSelect();

    uint32_t avg_x = 0;
    uint32_t avg_y = 0;
    uint8_t nsamples = 0;
    for(uint8_t i = 0; i < 16; i++) {
        if(!ILI9341_TouchPressed())
            break;

        nsamples++;

        HAL_SPI_Transmit(&ILI9341_TOUCH_SPI_PORT, (uint8_t*)cmd_read_y, sizeof(cmd_read_y), HAL_MAX_DELAY);
        uint8_t y_raw[2];
        HAL_SPI_TransmitReceive(&ILI9341_TOUCH_SPI_PORT, (uint8_t*)zeroes_tx, y_raw, sizeof(y_raw), HAL_MAX_DELAY);

        HAL_SPI_Transmit(&ILI9341_TOUCH_SPI_PORT, (uint8_t*)cmd_read_x, sizeof(cmd_read_x), HAL_MAX_DELAY);
        uint8_t x_raw[2];
        HAL_SPI_TransmitReceive(&ILI9341_TOUCH_SPI_PORT, (uint8_t*)zeroes_tx, x_raw, sizeof(x_raw), HAL_MAX_DELAY);

        avg_x += (((uint16_t)x_raw[0]) << 8) | ((uint16_t)x_raw[1]);
        avg_y += (((uint16_t)y_raw[0]) << 8) | ((uint16_t)y_raw[1]);
    }

    ILI9341_TouchUnselect();

    if(nsamples < 16)
        return false;

    uint32_t raw_x = (avg_x / 16);
    if(raw_x < ILI9341_TOUCH_MIN_RAW_X) raw_x = ILI9341_TOUCH_MIN_RAW_X;
    if(raw_x > ILI9341_TOUCH_MAX_RAW_X) raw_x = ILI9341_TOUCH_MAX_RAW_X;

    uint32_t raw_y = (avg_y / 16);
    if(raw_y < ILI9341_TOUCH_MIN_RAW_X) raw_y = ILI9341_TOUCH_MIN_RAW_Y;
    if(raw_y > ILI9341_TOUCH_MAX_RAW_Y) raw_y = ILI9341_TOUCH_MAX_RAW_Y;

    // Uncomment this line to calibrate touchscreen:
    // UART_Printf("raw_x = %d, raw_y = %d\r\n", x, y);

    *x = (raw_x - ILI9341_TOUCH_MIN_RAW_X) * ILI9341_TOUCH_SCALE_X / (ILI9341_TOUCH_MAX_RAW_X - ILI9341_TOUCH_MIN_RAW_X);
    *y = (raw_y - ILI9341_TOUCH_MIN_RAW_Y) * ILI9341_TOUCH_SCALE_Y / (ILI9341_TOUCH_MAX_RAW_Y - ILI9341_TOUCH_MIN_RAW_Y);

    return true;
}