How does FreeRTOS allocate more service time (CPU cycles) to higher priority level task?

[GolamMostafa]

I have been experimenting with the following setup (Fig-1) and the sketch to understand the mechanism of FreeRTOS in allocating more time to Task11 (with higher priority level 2) than Tasks10 with priority level 1. Would appreciate you explain this mechanism.
Sketch:

Code: Untitled.cpp Select all

TaskHandle_t Task10Handle;

TaskHandle_t Task11Handle;



void setup()

{

  Serial.begin(115200);

  analogReadResolution(12);



  xTaskCreatePinnedToCore(Task10, "Task-10", 2048, NULL, 1, &Task10Handle, 1);

  xTaskCreatePinnedToCore(Task11, "Task-11", 2048, NULL, 2, &Task11Handle, 1);

}



void loop() {}



void Task10(void *pvParameters)

{

  while (true)

  {

    int analogValue34 = analogRead(34);

    Serial.print("ADC1_6: "); Serial.println(analogValue34);

    vTaskDelay(pdMS_TO_TICKS(1000)); // 

  }

}



void Task11(void *pvParameter)

{

  while (true)

  {

    int analogValue35 = analogRead(35);

    Serial.print("ADC1_7: "); Serial.println(analogValue35);

    vTaskDelay(pdMS_TO_TICKS(1000)); // 

  }

}

[Sprite]

It won't. Given different priorities, FreeRTOS always allocates 100% of the time to the highest-priority task that is not blocking: it will always run that task until the task runs into something that de-schedules it (like the vTaskDelay in your example). See also here.

[GolamMostafa]

Thanks for the reply.

[GolamMostafa]

I have prepared and tested the following three tasks sketch that blinks three LEDs concurrently at different blink rates. Are there anything exaggerate particulalry on the definition of Tick Time and Time Slice (Fig-2)?

Schematic:

esp32-3led.png (11.07 KiB) Viewed 2493 times

Figure-1

Task State Diagram:

taskStateDiag.png (36.71 KiB) Viewed 2504 times

Figure-2:

Sketch:

Code: Untitled.cpp Select all

TaskHandle_t Task10Handle;

TaskHandle_t Task11Handle;



#define LED 2     //BLU

#define LED10 21  //RED

#define LED11 22  //GRN



void setup()

{

  Serial.begin(115200);

  pinMode(LED, OUTPUT);

  pinMode(LED10, OUTPUT);

  pinMode(LED11, OUTPUT);



  xTaskCreatePinnedToCore(Task10, "Task-10", 2048, NULL, 2, &Task10Handle, 1);//RED LED10

  xTaskCreatePinnedToCore(Task11, "Task-11", 2048, NULL, 3, &Task11Handle, 1);//GRN LED11

}



void loop()//BLU

{

  digitalWrite(LED, HIGH);

  vTaskDelay(1500);

  digitalWrite(LED, LOW);

  vTaskDelay(1500);

}



void Task10(void *pvParameters)//RED

{

  while (true)

  {

    digitalWrite(LED10, HIGH);

    vTaskDelay(500);

    digitalWrite(LED10, LOW);

    vTaskDelay(500);

  }

}



void Task11(void *pvParameters)//GRN

{

  while (true)

  {

    digitalWrite(LED11, HIGH);

    vTaskDelay(250);

    digitalWrite(LED11, LOW);

    vTaskDelay(250);

  }

}