gen2: basic touch sensor support (#17)

Play audio sample on touch event.

src/main.c

@@ -11,10 +11,16 @@
 #include "gfx.h"
 #include "remote.h"
 #include "sdkconfig.h"
+#include "touch.h"
 #include "wifi.h"
 
 static const char* TAG = "main";
 
+void _on_touch() {
+  ESP_LOGI(TAG, "Touch detected");
+  audio_play(ASSET_LAZY_DADDY_MP3, ASSET_LAZY_DADDY_MP3_LEN);
+}
+
 void app_main(void) {
   ESP_LOGI(TAG, "Hello world!");
 
@@ -45,6 +51,12 @@ void app_main(void) {
     return;
   }
 
+  // Setup touch.
+  if (touch_initialize(_on_touch) != ESP_OK) {
+    ESP_LOGE(TAG, "failed to initialize touch");
+    return;
+  }
+
   uint8_t mac[6];
   if (!wifi_get_mac(mac)) {
     ESP_LOGI(TAG, "WiFi MAC: %02x:%02x:%02x:%02x:%02x:%02x", mac[0], mac[1],

src/touch.c

@@ -0,0 +1,101 @@
+#include "touch.h"
+
+#ifdef TIDBYT_GEN2
+
+#include <driver/gpio.h>
+#include <driver/touch_pad.h>
+#include <esp_err.h>
+#include <esp_log.h>
+#include <esp_timer.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <stdint.h>
+
+#define TOUCH_PAD_NUM TOUCH_PAD_NUM8
+#define DEBOUNCE_TIME_MICROS (250 * 1000)
+#define TOUCH_FILTER_PERIOD_MILLIS 10
+
+const char *TAG = "touch";
+
+touch_callback_t _callback = NULL;
+uint16_t _threshold = 0;
+uint64_t _lastTouch = 0;
+
+static void _filterCallback(uint16_t *raw, uint16_t *filtered) {
+  uint16_t val = filtered[TOUCH_PAD_NUM];
+
+  uint64_t now = esp_timer_get_time();
+  if (val < _threshold && now - _lastTouch > DEBOUNCE_TIME_MICROS) {
+    _lastTouch = now;
+    if (_callback != NULL) {
+      _callback();
+    }
+  }
+}
+
+esp_err_t touch_initialize(touch_callback_t callback) {
+  _callback = callback;
+
+  esp_err_t err = touch_pad_init();
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  touch_pad_set_measurement_interval(TOUCH_PAD_SLEEP_CYCLE_DEFAULT / 4);
+  touch_pad_set_measurement_clock_cycles(TOUCH_PAD_MEASURE_CYCLE_DEFAULT / 2);
+
+  err = touch_pad_set_fsm_mode(TOUCH_FSM_MODE_TIMER);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  err = touch_pad_set_voltage(TOUCH_HVOLT_2V7, TOUCH_LVOLT_0V5,
+                              TOUCH_HVOLT_ATTEN_1V);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  err = touch_pad_filter_start(TOUCH_FILTER_PERIOD_MILLIS);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  err = touch_pad_config(TOUCH_PAD_NUM, 0);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  ESP_LOGI(TAG, "Reading current touch pad values");
+  uint16_t thresh = 0;
+  for (int i = 0; i < 3; i++) {
+    vTaskDelay(pdMS_TO_TICKS(100));
+    uint16_t x;
+    touch_pad_read_filtered(TOUCH_PAD_NUM, &x);
+
+    if (x > thresh) {
+      thresh = x;
+    }
+  }
+
+  _threshold = (thresh * 95) / 100;
+
+  ESP_LOGI(TAG, "Touch threshold: %d", _threshold);
+
+  err = touch_pad_config(TOUCH_PAD_NUM, 0);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  err = touch_pad_set_filter_read_cb(_filterCallback);
+  if (err != ESP_OK) {
+    return err;
+  }
+
+  return ESP_OK;
+}
+
+#else
+
+esp_err_t touch_initialize(touch_callback_t callback) { return ESP_OK; }
+
+#endif

src/touch.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <esp_err.h>
+
+typedef void (*touch_callback_t)();
+
+esp_err_t touch_initialize(touch_callback_t callback);