- examples: add 'Capacitive touch sensor read' example

- examples: add 'Capacitive touch sensor interrupts' example - Code review comments implemented - use only one image - add external picture of ESP32 Demo Board V2
2025-11-18 18:40:13 +00:00 · 2017-02-26 08:45:50 +01:00
parent 13dfb5568d
commit 41890f15b9
8 changed files with 234 additions and 0 deletions
--- a/examples/peripherals/touch_pad_interrupt/main/tp_interrupt_main.c
+++ b/examples/peripherals/touch_pad_interrupt/main/tp_interrupt_main.c
@@ -0,0 +1,109 @@
+/* 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_system.h"
+#include "nvs_flash.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()
+{
+    ESP_LOGI(TAG, "Starting");
+    nvs_flash_init();
+
+    // 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);
+}