RTOS learning

KlausST said:

Let´s say you have two simple tasks:
* blinking a LED with software (not hardware PWM, just as an example)
* and pollin

Click to expand...

• Purpose: Control LEDs based on received commands.
• Inputs: Commands.
• Outputs: LED control signals.
• Sequence of Operations:
  1. Monitor received commands.
  2. Determine LED control based on received commands.
  3. Control LEDs accordingly.
• Timing Constraints: LED updates can be less frequent than command reception.
• Priority Level: Lowest priority

• Purpose: Transmit data to a system using UART communication.
• Inputs: Data stored in a buffer.
• Outputs: UART transmission.
• Sequence of Operations:
  1. Read data from the buffer.
  2. Transmit data via UART to the central system.
• Timing Constraints: UART transmission can occur at regular intervals or based on sufficient data.
• Priority Level: Highest priority

andre_luis said:

There are numerous approaches with RTOS'es that could meet that, so even if at a glance the above scenario seems ok, only by putting the hands-on, coding, looking and feeling you will indeed understand what resources are needed or missed; so the next step is to make a sketch and select what to use ( e.g. queue, mailbox, mutex, etc... ).

Click to expand...

//ESP32 and Arduino IDE C langauge 

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

#define LED_PIN 2
#define BAUD_RATE 115200

TaskHandle_t uartTaskHandle = NULL;
TaskHandle_t ledTaskHandle = NULL;

volatile char receivedChar = 0;
volatile bool commandReceived = false;

void setup()
{
  Serial.begin(BAUD_RATE);
  pinMode(LED_PIN, OUTPUT);

  xTaskCreate(
    uartTask,
    "UART Task",
    1000,
    NULL,
    1,
    &uartTaskHandle
  );

  xTaskCreate(
    ledTask,
    "LED Task",
    1000,
    NULL,
    1,
    &ledTaskHandle
  );

  Serial.println("Setup completed.");
}

void loop()
{
}

void uartTask(void * parameter)
{
  while (1)
  {
    if (Serial.available())
    {
      receivedChar = Serial.read();
      Serial.print("UART Task: Received character: ");
      Serial.println(receivedChar);
      commandReceived = true;
    }
    vTaskDelay(pdMS_TO_TICKS(10));
  }
}

void ledTask(void * parameter)
{
  while (1)
  {
    if (commandReceived)
    {
      if (receivedChar == '1')
      {
        digitalWrite(LED_PIN, HIGH);
        vTaskDelay(pdMS_TO_TICKS(500));  // LED on for 500 ms
        digitalWrite(LED_PIN, LOW);
        vTaskDelay(pdMS_TO_TICKS(500));  // LED off for 500 ms
      }
      else if (receivedChar == '2')
      {
        digitalWrite(LED_PIN, HIGH);
        vTaskDelay(pdMS_TO_TICKS(100));  // LED on for 100 ms
        digitalWrite(LED_PIN, LOW);
        vTaskDelay(pdMS_TO_TICKS(100));  // LED off for 100 ms
      }
    }
    else
    {
      digitalWrite(LED_PIN, LOW);  // Turn off LED if no command received
    }
    vTaskDelay(pdMS_TO_TICKS(10));
  }
}

I noticed that the program seems to work fine even without the use of a mutex for synchronizing the access to the shared variables (receivedChar and commandReceived).

Click to expand...