ESP32 Forum

Posted: **Thu Dec 08, 2022 4:41 am**

Hi

I am trying to define a sleep function with esp_vApplicationIdleHook() but whenever I put it in my sketch there is an error:
Compilation error: ambiguating new declaration of 'bool esp_vApplicationIdleHook()'.

My code is simple like:

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bool esp_vApplicationIdleHook(void)
{
  static TickType_t lastFlashTime=0;
  if((xTaskGetTickCount()-lastFlashTime) > 1000)
  {
    Serial.println(F("It is 1 sec elapse in the idle hook."));
    lastFlashTime = xTaskGetTickCount();
  }
  return true;
}

How esp_vApplicationIdleHook(void) is used actually?

Thanks for any reply in advance.

John

Posted: **Thu Dec 08, 2022 6:46 am**

Not sure why you think that has a bool return type; the docs define it as `void vApplicationIdleHook( void )`.

Posted: **Thu Dec 08, 2022 7:10 am**

Right, it should be

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void esp_vApplicationIdleHook(void)

instead. This function is required by tasks.c and listed as a extern in portmacro.h.

Changing it back to void esp_vApplicationIdleHook(void) in the main sketch returns the error as :
multiple definition of `esp_vApplicationIdleHook'

I think it is not possible to use esp_vApplicationIdleHook() like vApplicationIdleHook() in legacy FreeRTOS. Instead, I need to call

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esp_register_freertos_idle_hook(esp_freertos_idle_cb_t new_idle_cb)

to register a new callback function and this time, the new callback function type is :

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typedef bool (*esp_freertos_idle_cb_t)(void)

. It returns a boolean and it is not possible to call Serial.printf() from the new callback otherwise, the application will crash. Suppose the new callback should return as soon as possible without a long delay.

ESP32 Forum

ambiguating new declaration of 'bool esp_vApplicationIdleHook()'

ambiguating new declaration of 'bool esp_vApplicationIdleHook()'

Re: ambiguating new declaration of 'bool esp_vApplicationIdleHook()'

Re: ambiguating new declaration of 'bool esp_vApplicationIdleHook()'