Implementation of the CST816S touch controller with esp_lcd_touch component.
Touch controller | Communication interface | Component name | Link to datasheet |
---|---|---|---|
CST816S | I2C | esp_lcd_touch_cst816s | datasheet |
Note
CONFIG_ESP_LCD_TOUCH_CST816S_DISABLE_READ_ID
to y
in menuconfig
.Packages from this repository are uploaded to Espressif's component service.
You can add them to your project via idf.py add-dependancy
, e.g.
Plaintext
idf.py add-dependency esp_lcd_touch_cst816s==1.0.0
Alternatively, you can create idf_component.yml
. More is in Espressif's documentation.
Define a mutex for the touch and create it before initialize the touch:
Plaintext
static SemaphoreHandle_t touch_mux;
touch_mux = xSemaphoreCreateBinary();
Define a callback function used by ISR:
Plaintext
static void touch_callback(esp_lcd_touch_handle_t tp)
{
BaseType_t xHigherPriorityTaskWoken = pdFALSE;
xSemaphoreGiveFromISR(touch_mux, &xHigherPriorityTaskWoken);
if (xHigherPriorityTaskWoken) {
portYIELD_FROM_ISR();
}
}
Initialization of the touch component.
Plaintext
esp_lcd_panel_io_i2c_config_t io_config = ESP_LCD_TOUCH_IO_I2C_CST816S_CONFIG();
esp_lcd_touch_config_t tp_cfg = {
.x_max = CONFIG_LCD_HRES,
.y_max = CONFIG_LCD_VRES,
.rst_gpio_num = CONFIG_LCD_TOUCH_RST,
.int_gpio_num = CONFIG_LCD_TOUCH_INT,
.levels = {
.reset = 0,
.interrupt = 0,
},
.flags = {
.swap_xy = 0,
.mirror_x = 0,
.mirror_y = 0,
},
.interrupt_callback = touch_callback,
};
esp_lcd_touch_handle_t tp;
esp_lcd_touch_new_i2c_cst816s(io_handle, &tp_cfg, &tp);
Read data from the touch controller and store it in RAM memory. It should be called regularly in poll.
Plaintext
if (xSemaphoreTake(touch_mux, 0) == pdTRUE) {
esp_lcd_touch_read_data(tp); // read only when ISR was triggled
}
Get one X and Y coordinates with strength of touch.
Plaintext
uint16_t touch_x[1];
uint16_t touch_y[1];
uint16_t touch_strength[1];
uint8_t touch_cnt = 0;
bool touchpad_pressed = esp_lcd_touch_get_coordinates(tp, touch_x, touch_y, touch_strength, &touch_cnt, 1);
idf.py add-dependency "espressif/esp_lcd_touch_cst816s^1.1.0"