integrate timer use into task

Author: bertmelis

README.md

@@ -5,7 +5,7 @@
 This is a DHT11/22 library for ESP32 using the RMT peripheral, for use in the Arduino framework.  
 For ESP8266, please look into this repo: [DHT](https://github.com/bertmelis/DHT)
 
-The library is non blocking, doesn't use delay and is usable in async frameworks. The library is kept simple on purpose. You are responsible yourself to follow the sensor's constraints (like polling frequency) and logical programming errors. Supplementary functions like dew point calculation are not included.
+The library is non blocking and is usable in async frameworks. Time consuming methods are offloaded to a separate task. The library is kept simple on purpose. You are responsible yourself to follow the sensor's constraints (like polling frequency) and logical programming errors. Supplementary functions like dew point calculation are not included.
 
 ## Installation
 

src/esp32DHT.cpp

@@ -33,28 +33,16 @@ DHT::DHT() :
   _channel(RMT_CHANNEL_0),
   _onData(nullptr),
   _onError(nullptr),
-  _timer(nullptr),
   _task(nullptr) {}
 
 DHT::~DHT() {
-  if (_timer) {  // if _timer is true, setup() has been called
-                 // so RMT driver is loaded and the aux task is
-                 // running
-    esp_timer_delete(_timer);
-    rmt_driver_uninstall(_channel);
-    vTaskDelete(_task);
-  }
+  rmt_driver_uninstall(_channel);
+  vTaskDelete(_task);
 }
 
 void DHT::setup(uint8_t pin, rmt_channel_t channel) {
   _pin = pin;
   _channel = channel;
-  esp_timer_create_args_t _timerConfig;
-  _timerConfig.arg = static_cast<void*>(this);
-  _timerConfig.callback = reinterpret_cast<esp_timer_cb_t>(_handleTimer);
-  _timerConfig.dispatch_method = ESP_TIMER_TASK;
-  _timerConfig.name = "esp32DHTTimer";
-  esp_timer_create(&_timerConfig, &_timer);
   rmt_config_t config;
   config.rmt_mode = RMT_MODE_RX;
   config.channel = _channel;
@@ -67,7 +55,7 @@ void DHT::setup(uint8_t pin, rmt_channel_t channel) {
   rmt_config(&config);
   rmt_driver_install(_channel, 400, 0);  // 400 words for ringbuffer containing pulse trains from DHT
   rmt_get_ringbuf_handle(_channel, &_ringBuf);
-  xTaskCreate((TaskFunction_t)&_handleData, "esp32DHT", 2048, this, 5, &_task);
+  xTaskCreate((TaskFunction_t)&_readSensor, "esp32DHT", 2048, this, 5, &_task);
   pinMode(_pin, OUTPUT);
   digitalWrite(_pin, HIGH);
 }
@@ -81,11 +69,7 @@ void DHT::onError(esp32DHTInternals::OnError_CB callback) {
 }
 
 void DHT::read() {
-  // _pin should be set to OUTPUT and HIGH
-  digitalWrite(_pin, LOW);
-  esp_timer_start_once(_timer, 18 * 1000);  // timer is in microseconds
-  _data[0] = _data[1] = _data[2] = _data[3] = _data[4] = 0;
-  _status = 0;
+  xTaskNotifyGive(_task);
 }
 
 const char* DHT::getError() const {
@@ -107,17 +91,27 @@ const char* DHT::getError() const {
   return "UNKNOWN";
 }
 
-void DHT::_handleTimer(DHT* instance) {
-  pinMode(instance->_pin, INPUT);
-  rmt_rx_start(instance->_channel, 1);
-  rmt_set_pin(instance->_channel, RMT_MODE_RX, static_cast<gpio_num_t>(instance->_pin));  // reset after using pin as output
-  xTaskNotifyGive(instance->_task);
-}
-
-void DHT::_handleData(DHT* instance) {
+void DHT::_readSensor(DHT* instance) {
   size_t rx_size = 0;
   while (1) {
-    ulTaskNotifyTake(pdTRUE, portMAX_DELAY);  // block and wait for notification
+    // reset
+    instance->_data[0] = 
+    instance->_data[1] = 
+    instance->_data[2] = 
+    instance->_data[3] = 
+    instance->_data[4] = 0;
+    instance->_status = 0;
+
+    // block and wait for notification
+    ulTaskNotifyTake(pdTRUE, portMAX_DELAY);
+
+    // give start signal to sensor
+    digitalWrite(instance->_pin, LOW);
+    vTaskDelay(18);
+    pinMode(instance->_pin, INPUT);
+    rmt_rx_start(instance->_channel, 1);
+    rmt_set_pin(instance->_channel, RMT_MODE_RX, static_cast<gpio_num_t>(instance->_pin));  // reset after using pin as output
+    
     // blocks until data is available or timeouts after 1000
     rmt_item32_t* items = static_cast<rmt_item32_t*>(xRingbufferReceive(instance->_ringBuf, &rx_size, 1000));
     if (items) {
@@ -132,6 +126,8 @@ void DHT::_handleData(DHT* instance) {
       pinMode(instance->_pin, OUTPUT);
       digitalWrite(instance->_pin, HIGH);
     }
+
+    // return results
     instance->_tryCallback();
   }
 }

src/esp32DHT.hpp

@@ -55,8 +55,7 @@ class DHT {
   uint8_t _data[5];
 
  private:
-  static void _handleTimer(DHT* instance);
-  static void _handleData(DHT* instance);
+  static void _readSensor(DHT* instance);
   void _decode(rmt_item32_t* data, int numItems);
   void _tryCallback();
   virtual float _getTemperature() = 0;
@@ -67,7 +66,6 @@ class DHT {
   rmt_channel_t _channel;
   esp32DHTInternals::OnData_CB _onData;
   esp32DHTInternals::OnError_CB _onError;
-  esp_timer_handle_t _timer;
   TaskHandle_t _task;
   RingbufHandle_t _ringBuf;
 };