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ESP LCD Touch CST816S - touch controller CST816S


# ESP LCD Touch CST816S Controller

[![Component Registry](](

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, there are two things about the driver are noteworthy (from [document](**

* It only responds to I2C commands after an event, such as a touch detection. Do not expect it to respond on init. Instead after a touch event, it will assert the IRQ and respond to I2C reads for a short time.
* While it should be able to detect multiple finger events, this version of the chip always returns only a single finger event and a gesture.

Reading the display data multiple times during a single event will return the last sampled finger position.

## Add to project

Packages from this repository are uploaded to [Espressif's component service](
You can add them to your project via ` add-dependancy`, e.g.
``` add-dependency esp_lcd_touch_cst816s==1.0.0

Alternatively, you can create `idf_component.yml`. More is in [Espressif's documentation](

## Example use

Define a mutex for the touch and create it before initialize the touch:

static SemaphoreHandle_t touch_mux;

touch_mux = xSemaphoreCreateBinary();

Define a callback function used by ISR:

static void touch_callback(esp_lcd_touch_handle_t tp)
    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
    xSemaphoreGiveFromISR(touch_mux, &xHigherPriorityTaskWoken);

    if (xHigherPriorityTaskWoken) {

Initialization of the touch component.

    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.

    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.

    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);


Supports all targets

License: Apache-2.0

To add this component to your project, run: add-dependency "espressif/esp_lcd_touch_cst816s^1.0.3"

or download archive


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espressif/esp_lcd_touch_cst816s version: 1.0.3