ESP32 Forum

Posted: **Sat Jul 08, 2017 4:13 am**

I have begun to interest in how FreeRTOS works, and because of I don't have my ESP32 yet, i decided to try it in my arduino micro. So, I note that the vTaskDelay in the arduino does a delay of 15ms because of the Watchdog timer, this is the piece of code that says it

Code: Select all

for (;;)
    {
      // read the input on analog pin 0:
      int sensorValue = analogRead(A0);
      // print out the value you read:
      Serial.println(sensorValue);
      vTaskDelay(1);  // one tick delay (15ms) in between reads for stability
    }

So, my question is, if I put a vTaskDelay(1) on my code, under ESP-IDF, What is the time that it took?.

I hope I have made myself clear, thank you.

Posted: **Sat Jul 08, 2017 4:32 am**

10ms, but can be changed

https://github.com/espressif/esp-idf/bl ... config#L38

Posted: **Sat Jul 08, 2017 4:47 am**

Thanks for answering so fast, so if I understand correctly, changing the value to 1000 hz (which is the max), will I get a 1ms delay?

Another question, in this line of code vTaskDelay(1000 / portTICK_PERIOD_MS); means that 1000*10 ms = 10s, but I know that it is a second delay so, the portTICK does something that i don't understand.

Maybe my questions are a little easy, but I don't want doubts. Thank you.

Posted: **Sat Jul 08, 2017 5:42 am**

portTICK_PERIOD_MS = 10
1000 / portTICK_PERIOD_MS = 100 ticks
100 * 10ms = 1 sec

However, a high tick frequency also means that the RTOS kernel will use more CPU time so be less efficient.

Posted: **Sat Jul 08, 2017 6:06 am**

Thank you very much, I appreciate the time you took to answer.

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