ESP32 and FreeRTOS delete a task

I have following program running on ESP32 I need help understanding how its working

void setup()
{
  Serial.begin(112500);
  /* we create a new task here */
  xTaskCreate(
  anotherTask, /* Task function. */
  "another Task", /* name of task. */
  10000, /* Stack size of task */
  NULL, /* parameter of the task */
  1, /* priority of the task */
  NULL); /* Task handle to keep track of created task */
}


void loop()
{
  Serial.println("Task 1");
  delay(1000);
}


void anotherTask( void * parameter )
{
/* loop forever */
for(;;)
{
   Serial.println("another Task");
   delay(1000);
}
/* delete a task when finish,
this will never happen because this is infinity loop */
vTaskDelete( NULL );
}

output

19:46:25.113 -> another Task
19:46:25.113 -> Task 1
19:46:26.111 -> another Task
19:46:26.111 -> Task 1
19:46:27.109 -> another Task
19:46:27.109 -> Task 1
19:46:28.090 -> another Task
19:46:28.090 -> Task 1
19:46:29.088 -> another Task
19:46:29.088 -> Task 1
19:46:30.117 -> another Task
19:46:30.117 -> Task 1
19:46:31.108 -> another Task
19:46:31.108 -> Task 1
19:46:32.105 -> another Task
19:46:32.105 -> Task 1
19:46:33.086 -> another Task
19:46:33.086 -> Task 1
19:46:34.082 -> another Task
19:46:34.082 -> Task 1
19:46:35.097 -> another Task
19:46:35.097 -> Task 1
19:46:36.108 -> another Task
19:46:36.108 -> Task 1
19:46:37.121 -> another Task
19:46:37.121 -> Task 1
19:46:38.117 -> another Task
19:46:38.117 -> Task 1
19:46:39.113 -> another Task
19:46:39.113 -> Task 1

https://www.freertos.org/a00126.html

Do you have a question?

In the code I have nener called scheduler so how th thread anotherTask is execuring ?

Hi,

My understanding is (I am new to this myself) that LOOP in your sketch is running as a task, when you issue the command "xTaskCreate" this then creates a second task (anotherTask) which starts running along side LOOP (so you then effectively have two programs running at the same time on the esp32).

I have been experimenting with using tasks myself recently and created this sketch which may be of interest/help

1 Like

As soon as that task is created it starts running.

With freeRTOS and an ESP32 putting code in the loop() defeats the memory cleanup functions and code in loop() is NOT guaranteed any run time as loop() has a priority if 1; the lowest priority.

/*
  https://github.com/G6EJD/ESP32-e-Paper-Weather-Display/blob/master/examples/Waveshare_4_2/Waveshare_4_2.ino
  Stole some code from that guy.
*/
#include "MyBitmap.h"
#include <WiFi.h>
#include <PubSubClient.h>
#include "certs.h"
#include "sdkconfig.h"
#include "esp_system.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"
#include <GxEPD2_BW.h>
#include <U8g2_for_Adafruit_GFX.h> // Select u8g2 font from here: https://github.com/olikraus/u8g2/wiki/fntlistall
#include <Fonts/FreeMonoBold9pt7b.h> //https://learn.adafruit.com/adafruit-gfx-graphics-library/using-fonts
#include <Fonts/FreeMono9pt7b.h>
#include <HardwareSerial.h>
#include <SimpleKalmanFilter.h>
#include "MHZ19.h"
#include <ESP32Time.h>
#include <SolarCalculator.h>
////
ESP32Time rtc;
MHZ19 myMHZ19;
GxEPD2_BW<GxEPD2_420, GxEPD2_420::HEIGHT> display(GxEPD2_420(/*CS=5*/ SS, /*DC=*/ 17, /*RST=*/ 16, /*BUSY=*/ 4)); // GDEW042T2
Adafruit_BME680 bme( GPIO_NUM_15 );
WiFiClient   wifiClient; // do the WiFi instantiation thing
PubSubClient MQTTclient( mqtt_server, mqtt_port, wifiClient );
U8G2_FOR_ADAFRUIT_GFX u8g2Fonts;
////
#define evtStoreAirPressure   ( 1 << 0 )
#define evtWaitForBME         ( 1 << 1 )
#define evtParseMQTT          ( 1 << 3 )
#define evtDisplayUpdate      ( 1 << 4 )
#define evtDoBME              ( 1 << 5 )
#define OneMinuteGroup ( evtDoBME )
EventGroupHandle_t eg;
//////
QueueHandle_t xQ_WindChillDewPoint;
QueueHandle_t xQ_eData;
struct stu_eData
{
  float  oTemperature = 0.0f;
  float  oHumidity    = 0.0f;
  float  oPressure    = 0.0f;
  // for outside aqi???????????????????????? what does the RPi send an int or float???
  float  Temperature  = 0.0f;
  float  Pressure    = 0.0f;
  float  Humidity    = 0.0f;
  float  IAQ         = 0.0f; // Index Air Quality
  float  RM0         = 0.0f; // Remaining Moisture from sensor 0
  //float  PM2         = 0.0f; // particles in air
  float  WS          = 0.0f; // wind speed
  String WD          = "";   // wind direction
  float  RF          = 0.0f; // rainfall
  //float  WSV         = 0.0f; // weather station volts
  //float  WSC         = 0.0f; // weather station current
  //float  WSP         = 0.0f; // weather station power
  float  WindChill   = 0.0f; //windchill
  float  DewPoint    = 0.0f; //dew point or dew index
  int    SunRiseHr   = 0;    // sunrise hour
  int    SunRiseMin  = 0;    //sunrise minute
  int    SunSetHr    = 0;    //sunset hour
  int    SunSetMin   = 0;    //sunset minute
  int    DuskHr      = 0;    //dusk
  int    DuskMin     = 0;    //dusk
  int    DawnHr      = 0;    // dawn
  int    DawnMin     = 0;    // dawn
  int    TransitHr   = 0;    // 'noon' time
  int    TransitMin  = 0;    // 'noon' time
  double azimuth     = 0.0f;   // Sun's azimuth, in degrees
  double elevation   = 0.0f;     // Sun's elevation, in degrees
  float  CO2         = 0.0f;
  float  PressureH   = 0.0f;
  float  PressureL   = 10000.0f;
} x_eData; // environmental data
QueueHandle_t xQ_Message; // payload and topic queue of MQTT payload and topic
const int payloadSize = 100;
struct stu_message
{
  char payload [payloadSize] = {'\0'};
  String topic ;
} x_message;
////
const float oGasResistanceBaseLine = 149598.0f;
int mqttOK = 0;
volatile bool TimeSet = false;
const int BufferCount = 60;
float CollectionPressure[BufferCount] = {0.0f};
boolean LargeIcon = true, SmallIcon = false;
//bool CollectionDone = false;
#define Large  11           // For icon drawing, needs to be odd number for best effect
#define Small  5            // For icon drawing, needs to be odd number for best effect
enum alignment {LEFT, RIGHT, CENTER};
SemaphoreHandle_t sema_MQTT_KeepAlive;
SemaphoreHandle_t sema_PublishPM;
SemaphoreHandle_t sema_mqttOK;
SemaphoreHandle_t sema_CollectPressure;
////
//serial(2) = pin25 RX, pin26 TX
HardwareSerial co2Serial ( 2 );
////
void IRAM_ATTR onTimer()
{
  BaseType_t xHigherPriorityTaskWoken;
  xEventGroupSetBitsFromISR(eg, OneMinuteGroup, &xHigherPriorityTaskWoken);
} // void IRAM_ATTR onTimer()
// interrupt service routine for WiFi events put into IRAM
void IRAM_ATTR WiFiEvent(WiFiEvent_t event)
{
  switch (event) {
      break;
    default: break;
  }
} // void IRAM_ATTR WiFiEvent(WiFiEvent_t event)
void IRAM_ATTR mqttCallback(char* topic, byte * payload, unsigned int length)
{
  memset( x_message.payload, '\0', payloadSize ); // clear payload char buffer
  x_message.topic = ""; //clear topic string buffer
  x_message.topic = topic; //store new topic
  int i = 0; // extract payload
  for ( i; i < length; i++)
  {
    x_message.payload[i] = ((char)payload[i]);
  }
  x_message.payload[i] = '\0';
  xQueueOverwrite( xQ_Message, (void *) &x_message );// send data to queue
} // void mqttCallback(char* topic, byte* payload, unsigned int length)
////
void setup()
{
  // hardware timer 4 set for one minute alarm
  hw_timer_t * timer = NULL;
  timer = timerBegin( 3, 80, true );
  timerAttachInterrupt( timer, &onTimer, true );
  timerAlarmWrite(timer, 60000000, true);
  timerAlarmEnable(timer);
  ///
  co2Serial.begin( 9600 , SERIAL_8N1, 25, 26 ); // pin25 RX, pin26 TX
  x_eData.WD.reserve(50);
  x_message.topic.reserve( payloadSize );
  xQ_WindChillDewPoint = xQueueCreate( 1, sizeof(stu_eData) );
  xQ_Message  = xQueueCreate( 1, sizeof(stu_message) );
  xQ_eData    = xQueueCreate( 1, sizeof(stu_eData) ); // sends a queue copy of the structure
  //
  sema_PublishPM = xSemaphoreCreateBinary();
  xSemaphoreGive( sema_PublishPM );
  sema_mqttOK    =  xSemaphoreCreateBinary();
  xSemaphoreGive( sema_mqttOK );
  sema_CollectPressure = xSemaphoreCreateBinary();
  xSemaphoreGive( sema_CollectPressure );
  //
  eg = xEventGroupCreate(); // get an event group handle
  //
  xTaskCreatePinnedToCore( fparseMQTT, "fparseMQTT", 7000,  NULL, 5, NULL, 1 );
  xTaskCreatePinnedToCore( MQTTkeepalive, "MQTTkeepalive", 5000, NULL, 6, NULL, 1 );
  xTaskCreatePinnedToCore( DoTheBME680Thing, "DoTheBME280Thing", 20000, NULL, 5, NULL, 1);
  xTaskCreatePinnedToCore( fmqttWatchDog, "fmqttWatchDog", 5000, NULL, 3, NULL, 1 );
  xTaskCreatePinnedToCore( fDoTheDisplayThing, "fDoTheDisplayThing", 30000, NULL, 3, NULL, 1 );
  xTaskCreatePinnedToCore( fGetCO2, "fGetCO2", 4500, NULL, 2, NULL, 1 );
  xTaskCreatePinnedToCore( fParseDewPointWindChill, "fParseDewPointWindChill", 4500, NULL, 2, NULL, 1 );
  xTaskCreatePinnedToCore( fSolarCalculations, "fSolarCalculations", 10000, NULL, 2, NULL, 1 );
  xTaskCreatePinnedToCore( fStoreAirPressure, "fStoreAirPressure", 10000, NULL, 2, NULL, 1 );
} //void setup()
////
void fStoreAirPressure ( void *pvParemeters )
{
  int cellCount = 58;
  int Ticks     = 118;
  bool Filled   = false;
  const int ticksTrigger = 120; // triggered at 1 minute intervals
  for (;;)
  {
    //triggered by BME which is triggered by the 1 minute hardware timer.
    xEventGroupWaitBits (eg, evtStoreAirPressure, pdTRUE, pdTRUE, portMAX_DELAY );
    xSemaphoreTake( sema_CollectPressure, portMAX_DELAY );
    if ( !Filled )
    {
      for ( int j = 0; j < BufferCount; j++ )
      {
        CollectionPressure[j] = x_eData.oPressure;
      }
      Filled = true;     
    } else {
      if ( Ticks == ticksTrigger )
      {
        //shift contents left and insert new value at the end
        for ( int i = 0; i <= BufferCount - 2; i++ )
        {
          CollectionPressure[i] = CollectionPressure[i + 1];
        }
      }
      CollectionPressure[BufferCount - 1] = x_eData.oPressure;
    }
    if ( x_eData.oPressure > x_eData.PressureH )
    {
      x_eData.PressureH = x_eData.oPressure;
    }
    if ( x_eData.oPressure < x_eData.PressureL )
    {
      x_eData.PressureL = x_eData.oPressure;
    }
    Ticks++;
    if ( Ticks >= (ticksTrigger + 1) )
    {
      Ticks = 1;
      cellCount++;
    }
    if ( cellCount == (BufferCount - 1) )
    {
      cellCount = 0;
    }
    xSemaphoreGive( sema_CollectPressure );
    //
    //log_i( " high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
  } //for (;;)
  vTaskDelete( NULL );

} //void fStoreAirPressure ( void *pvParemeters )
////
void fSolarCalculations ( void *pvParameters )
{
  double sunrise;  // Sunrise, in hours (UTC)
  double transit;  // Solar noon, in hours (UTC)
  double sunset;   // Sunset, in hours (UTC)
  double dawn;     // Civil dawn, in hours (UTC)
  double dusk;     // Civil dusk, in hours (UTC)
  //double rt_ascension;  // Sun's right ascension, in degrees
  //double declination;   // Sun's declination, in degrees
  const  float time_zone = -7.0f;
  TickType_t xLastWakeTime = xTaskGetTickCount();
  const TickType_t xFrequency = 1000; //delay for mS
  int count  = 3590;
  int monthX = 1;
  int dayX   = 1;
  for (;;)
  {
    if ( count % 60 == 0 )
    {
      if ( (rtc.getHour(true) >= 12) & (rtc.getHour(true) <= 23) )
      {
        dayX = 0;
      } else {
        dayX = 1;
      }
      calcSunriseSunset( rtc.getYear(), (rtc.getMonth() + monthX) , (rtc.getDay() + dayX), latitude, longitude, transit, sunrise, sunset );  // Calculate the times of sunrise, transit and sunset
      sunrise += time_zone;
      sunset  += time_zone;
      SolarTimeFormat( sunrise, 0 );
      SolarTimeFormat( sunset, 1 );
      calcCivilDawnDusk( rtc.getYear(), (rtc.getMonth() + monthX) , rtc.getDay(), latitude, longitude, transit, dawn, dusk); // Calculate the times of civil dawn and dusk (UTC)
      transit += time_zone;
      dawn    += time_zone;
      dusk    += time_zone;
      SolarTimeFormat( dawn, 2 );
      SolarTimeFormat( dusk, 3 );
      SolarTimeFormat( transit, 4 );
      calcHorizontalCoordinates( rtc.getYear(), (rtc.getMonth() + monthX) , rtc.getDay(),  rtc.getHour(true) , rtc.getMinute(), rtc.getSecond(), latitude, longitude, x_eData.azimuth, x_eData.elevation );
      x_eData.azimuth   = double(round(x_eData.azimuth * 100)) / 100; // Round to two decimal places
      x_eData.elevation = double(round(x_eData.elevation * 100)) / 100;
      if (count >= 3600 )
      {
        SolarTimeFormat( 0.0f, 5 ); // publish MQTT
        //log_i( "Hour:%d Azimuth %f, elevation %f, transit %dhr %dmin, dawn %dhr %dmin, dusk %dhr %dmin", rtc.getHour(true), x_eData.azimuth, x_eData.elevation, x_eData.TransitHr, x_eData.TransitMin, x_eData.DawnHr, x_eData.DawnMin, x_eData.DuskHr, x_eData.DuskMin );
        count = 0;
      }
    }
    //log_i( " high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
    xLastWakeTime = xTaskGetTickCount();
    vTaskDelayUntil( &xLastWakeTime, xFrequency );
    count++;
  } //for (;;)
  vTaskDelete( NULL );
} //void fSolarCalculations ( )
////
void SolarTimeFormat( double h, int i  )
{
  int hours   = 0;
  int minutes = 0;
  if ( h != 0.0f )
  {
    int m = int(round(h * 60));
    hours = (m / 60) % 24;
    minutes = m % 60;
  }
  switch ( i )
  {
    case 0:
      x_eData.SunRiseHr = hours;
      x_eData.SunRiseMin = minutes;
      break;
    case 1:
      x_eData.SunSetHr = hours;
      x_eData.SunSetMin = minutes;
      break;
    case 2:
      x_eData.DawnHr = hours;
      x_eData.DawnMin = minutes;
      break;
    case 3:
      x_eData.DuskHr = hours;
      x_eData.DawnMin = minutes;
      break;
    case 4:
      x_eData.TransitHr = hours;
      x_eData.TransitMin = minutes;
      break;
    case 5:
      String sTopic = "";
      sTopic.reserve( 35 );
      sTopic.concat( String(x_eData.SunRiseHr) + "," );
      sTopic.concat( String(x_eData.SunRiseMin) + "," );
      sTopic.concat( String(x_eData.SunSetHr) + "," );
      sTopic.concat( String(x_eData.SunSetMin) + "," );
      sTopic.concat( String(x_eData.DawnHr) + "," );
      sTopic.concat( String(x_eData.DawnMin) + "," );
      sTopic.concat( String(x_eData.TransitHr) + "," );
      sTopic.concat( String(x_eData.TransitMin) );
      xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
      MQTTclient.publish( topicSRSSDDT, sTopic.c_str() );
      xSemaphoreGive( sema_MQTT_KeepAlive );
      sTopic = "";
      sTopic.concat( String(x_eData.azimuth) + "," + String(x_eData.elevation) );
      xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
      MQTTclient.publish( topicAzEle, sTopic.c_str() );
      xSemaphoreGive( sema_MQTT_KeepAlive );
      sTopic = "";
      break;
  } // switch ( i ) {
} // void SolarTimeFormat( double h, int i  )
/*
  250-400ppm Normal background concentration in outdoor ambient air
  400-1,000ppm  Concentrations typical of occupied indoor spaces with good air exchange
  1,000-2,000ppm  Complaints of drowsiness and poor air.
  2,000-5,000 ppm Headaches, sleepiness and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
  5,000 Workplace exposure limit (as 8-hour TWA) in most jurisdictions.
  >40,000 ppm Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma, even death.
*/
void fParseDewPointWindChill( void *pvParameters )
{
  while ( !MQTTclient.connected() )
  {
    vTaskDelay( 250 );
  }
  struct stu_message px_message;
  String sDewPoint = "";
  String sWindChill = "";
  sDewPoint.reserve( payloadSize );
  sWindChill.reserve( payloadSize );
  for (;;)
  {
    if ( xQueueReceive(xQ_WindChillDewPoint, &px_message, portMAX_DELAY) == pdTRUE )
    {
      sDewPoint = px_message.payload;
      int commaIndex = sDewPoint.indexOf(',');
      sWindChill.concat ( sDewPoint.substring(0, commaIndex) );
      sDewPoint.remove( 0, (commaIndex + 1) );
      x_eData.WindChill = sWindChill.toFloat();
      x_eData.DewPoint = sDewPoint.toFloat();
      sDewPoint = "";
      sWindChill = "";
    }
    //log_i( " high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
  }
  vTaskDelete( NULL );
}
////
void fGetCO2 ( void *pvParameters )
{
  uint64_t TimePastKalman  = esp_timer_get_time();
  myMHZ19.begin( co2Serial );
  myMHZ19.autoCalibration();
  TickType_t xLastWakeTime = xTaskGetTickCount();
  const TickType_t xFrequency = 1000; //delay for mS
  SimpleKalmanFilter KF_CO2( 1.0f, 1.0f, .01f );
  for ( ;; )
  {
    KF_CO2.setProcessNoise( (esp_timer_get_time() - TimePastKalman) / 1000000.0f );
    x_eData.CO2 = KF_CO2.updateEstimate( myMHZ19.getCO2() ); // apply simple Kalman filter
    TimePastKalman = esp_timer_get_time();
    xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
    MQTTclient.publish( topicCO2, String(round(x_eData.CO2)).c_str() );
    xSemaphoreGive( sema_MQTT_KeepAlive );
    // process wind chill and dew point
    xLastWakeTime = xTaskGetTickCount();
    vTaskDelayUntil( &xLastWakeTime, xFrequency );
    //log_i( " high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
  }
  vTaskDelete( NULL );
} //void fMHZ19B ( void *pvParameters )
////
void fparseMQTT( void *pvParameters )
{
  struct stu_message px_message;
  for (;;)
  {
    if ( xQueueReceive(xQ_Message, &px_message, portMAX_DELAY) == pdTRUE )
    {
      xSemaphoreTake( sema_mqttOK, portMAX_DELAY );
      mqttOK = 0;
      xSemaphoreGive( sema_mqttOK );
      if (px_message.topic == topicAQIndex )
      {

      }

      if ( px_message.topic == topicOutsidePressure )
      {
        x_eData.oPressure = String(px_message.payload).toFloat();
      }
      if ( px_message.topic == topicOutsideHumidity )
      {
        x_eData.oHumidity = String(px_message.payload).toFloat();
      }
      if ( px_message.topic == topicOutsideTemperature )
      {
        x_eData.oTemperature = String(px_message.payload).toFloat();
      }
      if ( px_message.topic == topicRemainingMoisture_0 )
      {
        x_eData.RM0  = String(px_message.payload).toFloat();
      }
      if ( px_message.topic == topicWindSpeed )
      {
        x_eData.WS = String(px_message.payload).toFloat();
      }
      if ( px_message.topic == topicWindDirection )
      {
        x_eData.WD = "";
        x_eData.WD = String(px_message.payload);
      }
      if ( px_message.topic == topicRainfall )
      {
        x_eData.RF = String(px_message.payload).toFloat();
      }

      //      if ( px_message.topic == topicWSVolts )
      //      {
      //        x_eData.WSV = String(px_message.payload).toFloat();
      //      }
      //      if ( px_message.topic == topicWSCurrent )
      //      {
      //        x_eData.WSC = String(px_message.payload).toFloat();
      //      }
      //      if ( px_message.topic == topicWSPower )
      //      {
      //        x_eData.WSP = String(px_message.payload).toFloat();
      //      }
      if ( px_message.topic == topicDPnWI )
      {
        xQueueSend( xQ_WindChillDewPoint, (void *) &px_message, 1 );
      }
      if ( String(px_message.topic) == topicOK )
      {
        if ( !TimeSet)
        {
          String temp = "";
          temp.reserve(50);
          temp.concat( String(px_message.payload[0]) );
          temp.concat( String(px_message.payload[1]) );
          temp.concat( String(px_message.payload[2]) );
          temp.concat( String(px_message.payload[3]) );
          int year =  temp.toInt();
          temp = "";
          temp.concat( String(px_message.payload[5]) + String(px_message.payload[6]) );
          int month =  temp.toInt();
          temp =  "";
          temp.concat(String(px_message.payload[8]) + String(px_message.payload[9]) );
          int day =  temp.toInt();
          temp = "";
          temp.concat( String(px_message.payload[11]) + String(px_message.payload[12]) );
          int hour =  temp.toInt();
          temp = "";
          temp.concat( String(px_message.payload[14]) + String(px_message.payload[15]) );
          int min =  temp.toInt();
          rtc.setTime( 0, min, hour, day, month, year );
          log_i( "rtc  %s Year %d month %d day %d", rtc.getTime(), rtc.getYear(), (rtc.getMonth() + 1), rtc.getDay() );
          TimeSet = true;
        }
      }
    } //if ( xQueueReceive(xQ_Message, &px_message, portMAX_DELAY) == pdTRUE )
  } //for(;;)
  vTaskDelete( NULL );
} // void fparseMQTT( void *pvParameters )
////
void fDoTheDisplayThing( void * parameter )
{
  struct stu_eData px_eData;
  const char HelloWorld[] = "Hello World!";
  //display.init();
  //display.setFont(&FreeMonoBold9pt7b);
  //display.setTextColor(GxEPD_BLACK);
  int yIncrement = 18;
  int CurrentY = 20;
  int CurrentX = 5;
  String temp1 = "";
  temp1.reserve(10);
  String temp2 = "";
  temp2.reserve(10);
  int boxSpacing = 80;
  size_t item_size;
  for (;;)
  {

    // add in dew point display


    xEventGroupWaitBits (eg, evtDisplayUpdate, pdTRUE, pdTRUE, portMAX_DELAY );
    //log_i( "pip" );
    CurrentY = 20;
    display.init();
    //display.setFont(&FreeMonoBold9pt7b);
    display.setFont(&FreeMono9pt7b);
    //u8g2Fonts.setFont(u8g2_font_helvB08_tf);
    display.setTextColor(GxEPD_BLACK);
    display.setFullWindow();
    display.fillScreen(GxEPD_WHITE); // set the background to white (fill the buffer with value for white)
    display.setCursor( CurrentX, CurrentY );
    // first line
    display.drawRect( CurrentX, CurrentY , 70, 55, GxEPD_BLACK);
    display.drawBitmap( CurrentX + 10, CurrentY + 5, temperature_icon16x16, 16, 16, GxEPD_BLACK);
    display.setCursor( CurrentX + 30, CurrentY + 15 );
    //display.print( char(223) + "F" );
    display.print( "F" );
    display.setCursor( CurrentX + 10, CurrentY + 40);
    display.print( String(x_eData.oTemperature) );
    display.drawRect( CurrentX + boxSpacing, CurrentY , 70, 55, GxEPD_BLACK);
    display.setCursor( CurrentX + 90, CurrentY + 15 );
    display.print( "R.H.");
    display.setCursor( CurrentX + 90, CurrentY + 35 );
    display.print( String((int)x_eData.oHumidity) );
    // end of first line
    if ( x_eData.SunRiseMin < 10 )
    {
      temp1.concat( "0" + String(x_eData.SunRiseMin) );
    } else {
      temp1.concat( String(x_eData.SunRiseMin) );
    }
    if ( x_eData.SunSetMin < 10 )
    {
      temp2.concat( "0" + String(x_eData.SunSetMin) );
    } else {
      temp2.concat( String(x_eData.SunSetMin) );
    }
    CurrentY += yIncrement;
    CurrentY += yIncrement;
    CurrentY += yIncrement;
    display.setCursor( CurrentX, CurrentY );

    display.print( "Wind: " );
    CurrentY += yIncrement;
    display.setCursor( CurrentX, CurrentY );
    display.print( "Speed " + String(x_eData.WS) + "KPH, Dir " + String(x_eData.WD) + " Chill " + String(x_eData.WindChill) + "F" );
    CurrentY += yIncrement;
    CurrentY += yIncrement;
    display.drawRect( CurrentX, CurrentY , 70, 55, GxEPD_BLACK);
    addsun( 35, CurrentY + 30 , Small, SmallIcon );
    display.setCursor( CurrentX + 5, CurrentY + 15 );
    display.print( "0" + String(x_eData.SunRiseHr) + ":" + temp1 );
    display.setCursor( CurrentX + 5, CurrentY + 50 );
    display.print( String(x_eData.SunSetHr) + ":" + temp2 );
    display.drawRect( CurrentX + boxSpacing, CurrentY , 70, 55, GxEPD_BLACK);
    addraindrop(CurrentX + 110, CurrentY + 15, 7);
    display.setCursor( CurrentX + 90, CurrentY + 35 );
    display.print( String(x_eData.RF) );
    display.setCursor( CurrentX + 100, CurrentY + 50 );
    display.print( "mm" );
    display.drawRect( CurrentX + (boxSpacing * 2 ), CurrentY , 70, 55, GxEPD_BLACK);
    display.setCursor( CurrentX + 177, CurrentY + 15 );
    display.print( "C02" );
    display.setCursor( CurrentX + 165, CurrentY + 35 );
    display.print( String(int(x_eData.CO2)) );
    display.setCursor( CurrentX + 165, CurrentY + 50 );
    display.print( "PPM" );
    display.drawRect( CurrentX + (boxSpacing * 3 ), CurrentY , 70, 55, GxEPD_BLACK);
    display.setCursor( CurrentX + 246, CurrentY + 15 );
    display.print( "AQI" );
    display.setCursor( CurrentX + 246, CurrentY + 35 );
    display.print( String(int(x_eData.IAQ)) );
    display.setCursor( CurrentX + 246, CurrentY + 50 );
    display.print( "%" );
    display.drawRect( CurrentX + (boxSpacing * 4 ), CurrentY , 70, 55, GxEPD_BLACK);
    display.setCursor( CurrentX + 327, CurrentY + 15 );
    display.print( "R.M." );
    display.setCursor( CurrentX + 327, CurrentY + 35 );
    display.print( String(int(x_eData.RM0)) + "%" );
    //make graph
    xSemaphoreTake( sema_CollectPressure, portMAX_DELAY );
    CurrentY += yIncrement * 6;
    display.setCursor( CurrentX, CurrentY); //set cursor position
    //display.drawLine( CurrentX, CurrentY, CurrentX + 200, CurrentY, GxEPD_BLACK);
    int BaseLine = CollectionPressure[0];
    int offsetX = 0;
    for ( int j = 0; j < BufferCount; j++ )
    {
      //log_i( " %d , %f", j,CollectionPressure[j] );
      if ( CollectionPressure[j] != 0.0f )
      {
        int yAdj = (int)CollectionPressure[j] - BaseLine;
        display.setCursor( CurrentX + offsetX, CurrentY + yAdj );
        display.print( "-" );
        offsetX += 5;
        log_i( "pressure %f item %d", CollectionPressure[j], j );
      }
    }
    xSemaphoreGive( sema_CollectPressure );
    temp2 = "";
    temp1 = "";
    //
    display.display(false); // full update
    display.hibernate();
    //log_i( "DoTheBME280Thing high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
  } //for (;;)
  vTaskDelete( NULL );
} //void fDoTheDisplayTHing( void * parameter )
////
void fmqttWatchDog( void * paramater )
{
  int UpdateImeTrigger = 86400; //seconds in a day
  int UpdateTimeInterval = 86300; // 1st time update in 100 counts
  int maxNonMQTTresponse = 15;
  for (;;)
  {
    vTaskDelay( 1000 );
    if ( mqttOK >= maxNonMQTTresponse )
    {
      ESP.restart();
    }
    xSemaphoreTake( sema_mqttOK, portMAX_DELAY );
    mqttOK++;
    xSemaphoreGive( sema_mqttOK );
    UpdateTimeInterval++; // trigger new time get
    if ( UpdateTimeInterval >= UpdateImeTrigger )
    {
      TimeSet = false; // sets doneTime to false to get an updated time after a days count of seconds
      UpdateTimeInterval = 0;
    }
  }
  vTaskDelete( NULL );
}
////
float fCalulate_IAQ_Index( int gasResistance, float Humidity)
{
  float hum_baseline = 40.0f;
  float hum_weighting = 0.25f;
  float gas_offset = 0.0f;
  float hum_offset = 0.0f;
  float hum_score = 0.0f;
  float gas_score = 0.0f;
  gas_offset = oGasResistanceBaseLine - float( gasResistance );
  hum_offset = float( Humidity ) - hum_baseline;
  // calculate hum_score as distance from hum_baseline
  if ( hum_offset > 0.0f )
  {
    hum_score = 100.0f - hum_baseline - hum_offset;
    hum_score /= ( 100.0f - hum_baseline );
    hum_score *= ( hum_weighting * 100.0f );
  } else {
    hum_score = hum_baseline + hum_offset;
    hum_score /= hum_baseline;
    hum_score *= ( 100.0f - (hum_weighting * 100.0f) );
  }
  //calculate gas score as distance from baseline
  if ( gas_offset > 0.0f )
  {
    gas_score = float( gasResistance ) / oGasResistanceBaseLine;
    gas_score *= ( 100.0f - (hum_weighting * 100.0f ) );
  } else {
    gas_score = 100.0f - ( hum_weighting * 100.0f );
  }
  return ( hum_score + gas_score );
} //void fCalulate_IAQ_Index( int gasResistance, float Humidity):
////
void DoTheBME680Thing( void *pvParameters )
{
  SPI.begin(); // initialize the SPI library
  vTaskDelay( 10 );
  if (!bme.begin()) {
    log_i("Could not find a valid BME680 sensor, check wiring!");
    while (1);
  }
  // Set up oversampling and filter initialization
  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms
  //wait for a mqtt connection
  while ( !MQTTclient.connected() )
  {
    vTaskDelay( 250 );
  }
  xEventGroupSetBits( eg, evtWaitForBME );
  String bmeInfo = "";
  bmeInfo.reserve( 100 );
  for (;;)
  {
    xEventGroupWaitBits (eg, evtDoBME, pdTRUE, pdTRUE, portMAX_DELAY );
    x_eData.Temperature  = bme.readTemperature();
    x_eData.Temperature  = ( x_eData.Temperature * 1.8f ) + 32.0f; // (Celsius x 1.8) + 32
    x_eData.Pressure     = bme.readPressure();
    x_eData.Pressure     = x_eData.Pressure / 133.3223684f; //converts to mmHg
    x_eData.Humidity     = bme.readHumidity();
    x_eData.IAQ          = fCalulate_IAQ_Index( bme.readGas(), x_eData.Humidity );
    //log_i( " temperature % f, Pressure % f, Humidity % f IAQ % f", x_eData.Temperature, x_eData.Pressure, x_eData.Humidity, x_eData.IAQ);
    bmeInfo.concat( String(x_eData.Temperature, 2) );
    bmeInfo.concat( "," );
    bmeInfo.concat( String(x_eData.Pressure, 2) );
    bmeInfo.concat( "," );
    bmeInfo.concat( String(x_eData.Humidity, 2) );
    bmeInfo.concat( "," );
    bmeInfo.concat( String(x_eData.IAQ, 2) );
    xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY );
    if ( MQTTclient.connected() )
    {
      MQTTclient.publish( topicInsideInfo, bmeInfo.c_str() );
    }
    xSemaphoreGive( sema_MQTT_KeepAlive );
    xSemaphoreGive( sema_PublishPM ); // release publish of dust density
    xSemaphoreTake( sema_mqttOK, portMAX_DELAY );
    mqttOK ++;
    xSemaphoreGive( sema_mqttOK );
    xEventGroupSetBits( eg, evtDisplayUpdate );
    bmeInfo = ""; // empty the string buffer
    findDewPointWithHumidity( x_eData.Humidity, x_eData.Temperature );
    xEventGroupSetBits( eg, evtStoreAirPressure );
    // log_i( "DoTheBME280Thing high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
  }
  vTaskDelete ( NULL );
}
////
/*
  Important to not set vTaskDelay/vTaskDelayUntil to less then 10. Errors begin to develop with the MQTT and network connection.
  makes the initial wifi/mqtt connection and works to keeps those connections open.
*/
void MQTTkeepalive( void *pvParameters )
{
  sema_MQTT_KeepAlive   = xSemaphoreCreateBinary();
  xSemaphoreGive( sema_MQTT_KeepAlive ); // found keep alive can mess with a publish, stop keep alive during publish
  MQTTclient.setKeepAlive( 90 ); // setting keep alive to 90 seconds makes for a very reliable connection, must be set before the 1st connection is made.
  TickType_t xLastWakeTime = xTaskGetTickCount();
  const TickType_t xFrequency = 250; //delay for ms
  for (;;)
  {
    //check for a is-connected and if the WiFi 'thinks' its connected, found checking on both is more realible than just a single check
    if ( (wifiClient.connected()) && (WiFi.status() == WL_CONNECTED) )
    {
      xSemaphoreTake( sema_MQTT_KeepAlive, portMAX_DELAY ); // whiles MQTTlient.loop() is running no other mqtt operations should be in process
      MQTTclient.loop();
      xSemaphoreGive( sema_MQTT_KeepAlive );
    }
    else {
      log_i( "MQTT keep alive found MQTT status % s WiFi status % s", String(wifiClient.connected()), String(WiFi.status()) );
      if ( !(wifiClient.connected()) || !(WiFi.status() == WL_CONNECTED) )
      {
        connectToWiFi();
      }
      connectToMQTT();
    }
    //log_i( " high watermark % d",  uxTaskGetStackHighWaterMark( NULL ) );
    xLastWakeTime = xTaskGetTickCount();
    vTaskDelayUntil( &xLastWakeTime, xFrequency );
  }
  vTaskDelete ( NULL );
}
////
void connectToMQTT()
{
  byte mac[5]; // create client ID from mac address
  WiFi.macAddress(mac); // get mac address
  String clientID = String(mac[0]) + String(mac[4]) ; // use mac address to create clientID
  while ( !MQTTclient.connected() )
  {
    MQTTclient.connect( clientID.c_str(), mqtt_username, mqtt_password );
    vTaskDelay( 250 );
  }
  MQTTclient.setCallback ( mqttCallback );
  MQTTclient.subscribe   ( topicOK );
  MQTTclient.subscribe   ( topicRemainingMoisture_0 );
  MQTTclient.subscribe   ( topicWindSpeed );
  MQTTclient.subscribe   ( topicWindDirection );
  MQTTclient.subscribe   ( topicDPnWI );
  MQTTclient.subscribe   ( topicOutsideTemperature );
  MQTTclient.subscribe   ( topicOutsideHumidity );
  MQTTclient.subscribe   ( topicOutsidePressure );
  MQTTclient.subscribe   ( topicRainfall );
} //void connectToMQTT()
void connectToWiFi()
{
  int TryCount = 0;
  while ( WiFi.status() != WL_CONNECTED )
  {
    TryCount++;
    WiFi.disconnect();
    WiFi.begin( SSID, PASSWORD );
    vTaskDelay( 4000 );
    if ( TryCount == 10 )
    {
      ESP.restart();
    }
  }
  WiFi.onEvent( WiFiEvent );
}
////
float findDewPointWithHumidity( float humi, float temperature )
{
  //Celcius
  float ans =  (temperature - (14.55 + 0.114 * temperature) * (1 - (0.01 * humi)) - pow(((2.5 + 0.007 * temperature) * (1 - (0.01 * humi))), 3) - (15.9 + 0.117 * temperature) * pow((1 - (0.01 * humi)), 14));
  //log_i( "%f", ans );
  return ans;
}
////
void addraindrop(int x, int y, int scale)
{
  display.fillCircle(x, y, scale / 2, GxEPD_BLACK);
  display.fillTriangle(x - scale / 2, y, x, y - scale * 1.2, x + scale / 2, y , GxEPD_BLACK);
  x = x + scale * 1.6; y = y + scale / 3;
  display.fillCircle(x, y, scale / 2, GxEPD_BLACK);
  display.fillTriangle(x - scale / 2, y, x, y - scale * 1.2, x + scale / 2, y , GxEPD_BLACK);
}
////
void addsun(int x, int y, int scale, bool IconSize)
{
  int linesize = 3;
  if (IconSize == SmallIcon) linesize = 1;
  display.fillRect(x - scale * 2, y, scale * 4, linesize, GxEPD_BLACK);
  display.fillRect(x, y - scale * 2, linesize, scale * 4, GxEPD_BLACK);
  display.drawLine(x - scale * 1.3, y - scale * 1.3, x + scale * 1.3, y + scale * 1.3, GxEPD_BLACK);
  display.drawLine(x - scale * 1.3, y + scale * 1.3, x + scale * 1.3, y - scale * 1.3, GxEPD_BLACK);
  if (IconSize == LargeIcon) {
    display.drawLine(1 + x - scale * 1.3, y - scale * 1.3, 1 + x + scale * 1.3, y + scale * 1.3, GxEPD_BLACK);
    display.drawLine(2 + x - scale * 1.3, y - scale * 1.3, 2 + x + scale * 1.3, y + scale * 1.3, GxEPD_BLACK);
    display.drawLine(3 + x - scale * 1.3, y - scale * 1.3, 3 + x + scale * 1.3, y + scale * 1.3, GxEPD_BLACK);
    display.drawLine(1 + x - scale * 1.3, y + scale * 1.3, 1 + x + scale * 1.3, y - scale * 1.3, GxEPD_BLACK);
    display.drawLine(2 + x - scale * 1.3, y + scale * 1.3, 2 + x + scale * 1.3, y - scale * 1.3, GxEPD_BLACK);
    display.drawLine(3 + x - scale * 1.3, y + scale * 1.3, 3 + x + scale * 1.3, y - scale * 1.3, GxEPD_BLACK);
  }
  display.fillCircle(x, y, scale * 1.3, GxEPD_WHITE);
  display.fillCircle(x, y, scale, GxEPD_BLACK);
  display.fillCircle(x, y, scale - linesize, GxEPD_WHITE);
}
////
void loop() { }

Something I'm currently working on.

1 Like

I have written following code just for experiement. I was expecting to print only first task because it has highest priority but my code is executing both tasks. I don't understand why the second task is executing

void setup()
{
  Serial.begin(112500);
  /* Create two tasks. */
  xTaskCreate( vTask1, "Task 1", 10000, NULL, 2, NULL); 
  xTaskCreate( vTask2, "Task 2", 10000, NULL, 1, NULL); 
}


void loop() {
  // Do nothing

}

void vTask1( void *pvParameters )
{
  /* As per most tasks, this task is implemented in an infinite loop. */
  for(;;)
  {
    Serial.println("Task 1 is running");
    delay(1000);
   }
}

void vTask2( void *pvParameters )
{
  
  for(;;)
  {
    Serial.println("Task 2 is running");
    delay(1000);
   }
}

02:01:51.278 -> Task 1 is running
02:01:51.278 -> Task 2 is running
02:01:52.275 -> Task 1 is running
02:01:52.275 -> Task 2 is running
02:01:53.257 -> Task 1 is running
02:01:53.257 -> Task 2 is running
02:01:54.254 -> Task 1 is running
02:01:54.254 -> Task 2 is running
02:01:55.252 -> Task 1 is running
02:01:55.252 -> Task 2 is running
02:01:56.252 -> Task 1 is running
02:01:56.252 -> Task 2 is running
02:01:57.250 -> Task 1 is running
02:01:57.250 -> Task 2 is running
02:01:58.263 -> Task 1 is running
02:01:58.263 -> Task 2 is running
02:01:59.243 -> Task 1 is running
02:01:59.243 -> Task 2 is running
02:02:00.274 -> Task 1 is running
02:02:00.274 -> Task 2 is running

if you do not want the 2nd task to execute change your code to.

xTaskCreate( vTask1, "Task 1", 10000, NULL, 2, NULL); 
 // xTaskCreate( vTask2, "Task 2", 10000, NULL, 1, NULL); 

Do you understand that as soon as a task is created it starts running?

Creating a task in this way will cause issues at some point.

You should always have a task destructor in case the task jumps the stack.

void vTaskxxxxxxxx( void *pvParameters )
{
  
  for(;;)
  {
   }
vTaskDelete ( NULL );
}

The vTaskDelete ( NULL ); prevents the task from doing to much damage to the other tasks in case a task jumps its stack.

Use vTaskDelay instead of delay()

How long does task 1 take to run its code? pico seconds. When task1 gets to sleep what happens next? Why task2 has time to run. so task2 runs and sleeps. task 1 is created slightly ahead of task2.

Got it, Thanks

Task1 runs first, it's the highest priority, then blocks for 250ms. Task2 runs next,

void setup()
{
  Serial.begin(112500);
  /* Create two tasks. */
  xTaskCreate( vTask1, "Task 1", 10000, NULL, 2, NULL); 
  xTaskCreate( vTask2, "Task 2", 10000, NULL, 1, NULL); 
}


void loop() {
  // Do nothing

}

void vTask1( void *pvParameters )
{
  /* As per most tasks, this task is implemented in an infinite loop. */
  for(;;)
  {
    Serial.println("Task 1 is running");
     vTaskDelay(250); 
   }
}

void vTask2( void *pvParameters )
{
  
  for(;;)
  {
    Serial.println("Task 2 is running");
     vTaskDelay(750); 
   }
}

04:23:30.281 -> Task 1 is running
04:23:30.519 -> Task 1 is running
04:23:30.787 -> Task 1 is running
04:23:30.787 -> Task 2 is running
04:23:31.023 -> Task 1 is running
04:23:31.292 -> Task 1 is running
04:23:31.530 -> Task 1 is running
04:23:31.530 -> Task 2 is running
04:23:31.766 -> Task 1 is running
04:23:32.051 -> Task 1 is running
04:23:32.288 -> Task 1 is running
04:23:32.288 -> Task 2 is running
04:23:32.524 -> Task 1 is running
04:23:32.761 -> Task 1 is running
04:23:33.046 -> Task 1 is running
04:23:33.046 -> Task 2 is running
04:23:33.268 -> Task 1 is running
04:23:33.539 -> Task 1 is running
04:23:33.775 -> Task 1 is running
04:23:33.775 -> Task 2 is running
04:23:34.045 -> Task 1 is running
04:23:34.283 -> Task 1 is running
04:23:34.522 -> Task 1 is running
04:23:34.522 -> Task 2 is running
04:23:34.806 -> Task 1 is running
04:23:35.041 -> Task 1 is running
04:23:35.281 -> Task 1 is running

I recommend getting into the habit of using xTaskCreatePinnedToCore.

1 Like

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