esp-idf/examples/peripherals/touch_pad_interrupt/main/tp_interrupt_main.c

/* Touch Pad Interrupt Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"

#include "driver/touch_pad.h"
#include "soc/rtc_cntl_reg.h"
#include "soc/sens_reg.h"

static const char* TAG = "Touch pad";

static bool touch_pad_activated[TOUCH_PAD_MAX];


/*
  Read values sensed at all available touch pads.
  Use half of read value as the threshold
  to trigger interrupt when the pad is touched.
  Note: this routine demonstrates a simple way
  to configure activation threshold for the touch pads.
  Do not touch any pads when this routine
  is running (on application start).
 */
static void touch_pad_set_thresholds(void)
{
    uint16_t touch_value;
    for (int i=0; i<TOUCH_PAD_MAX; i++) {
        ESP_ERROR_CHECK(touch_pad_read(i, &touch_value));
        ESP_ERROR_CHECK(touch_pad_config(i, touch_value/2));
    }
}

/*
  Check if any of touch pads has been activated
  by reading a table updated by rtc_intr()
  If so, then print it out on a serial monitor.
  Clear related entry in the table afterwards
 */
static void touch_pad_read_task(void *pvParameter)
{
    static int show_message;
    while (1) {
        for (int i=0; i<TOUCH_PAD_MAX; i++) {
            if (touch_pad_activated[i] == true) {
                ESP_LOGI(TAG, "T%d activated!", i);
                // Wait a while for the pad being released
                vTaskDelay(200 / portTICK_PERIOD_MS);
                // Clear information on pad activation
                touch_pad_activated[i] = false;
                // Reset the counter triggering a message
                // that application is running
                show_message = 1;
            }
        }
        // If no pad is touched, every couple of seconds, show a message
        // that application is running
        if (show_message++ % 500 == 0) {
            ESP_LOGI(TAG, "Waiting for any pad being touched...");
        }
        vTaskDelay(10 / portTICK_PERIOD_MS);
    }
}

/*
  Handle an interrupt triggered when a pad is touched.
  Recognize what pad has been touched and save it in a table.
 */
static void touch_pad_rtc_intr(void * arg)
{
    uint32_t pad_intr = READ_PERI_REG(SENS_SAR_TOUCH_CTRL2_REG) & 0x3ff;
    uint32_t rtc_intr = READ_PERI_REG(RTC_CNTL_INT_ST_REG);
    //clear interrupt
    WRITE_PERI_REG(RTC_CNTL_INT_CLR_REG, rtc_intr);
    SET_PERI_REG_MASK(SENS_SAR_TOUCH_CTRL2_REG, SENS_TOUCH_MEAS_EN_CLR);

    if (rtc_intr & RTC_CNTL_TOUCH_INT_ST) {
        for (int i = 0; i < TOUCH_PAD_MAX; i++) {
            if ((pad_intr >> i) & 0x01) {
                touch_pad_activated[i] = true;
            }
        }
    }
}


void app_main()
{
    // Initialize touch pad peripheral
    ESP_LOGI(TAG, "Initializing touch pad");
    touch_pad_init();
    touch_pad_set_thresholds();
    touch_pad_isr_handler_register(touch_pad_rtc_intr, NULL, 0, NULL);

    // Start a task to show what pads have been touched
    xTaskCreate(&touch_pad_read_task, "touch_pad_read_task", 2048, NULL, 5, NULL);
}