Why does HAL_UART_TRANSMIT block my adc routine?

[MVan.16]

I am using stm32cube with the HAL functions to start my project. I have everything running fine. I have my adc trigger using OCP2 of my pwm and this works like a charm. But wen i use the uart somehow my adc does not want to trigger anymore and i do not get any interrupts for the adc anymore. How can the UART do this even when it does not use interrupts?

[Bob S]

Please post your code. Otherwise its just pot shots in the dark. Which style of HAL functions are you using: polled, interrupt or DMA? If the answer is "polled", my response is "don't do that".

[Tesla DeLorean]

Depends where you use it. If you use the HAL UART Transmit in a callback it can block interrupts. Callbacks are done under interrupt context.

[MVan.16]

Sorry, here is my code.

int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
  
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_ADC3_Init();
  MX_DAC1_Init();
  MX_ETH_Init();
  MX_HRTIM_Init();
  MX_TIM2_Init();
  MX_UART4_Init();
  MX_USB_OTG_FS_PCD_Init();
  /* USER CODE BEGIN 2 */
 
  HAL_HRTIM_WaveformCountStart(&hhrtim,(HRTIM_TIMERID_MASTER | HRTIM_TIMERID_TIMER_A | HRTIM_TIMERID_TIMER_C));//start master,timer A and timer C
  HAL_HRTIM_WaveformOutputStart(&hhrtim,(HRTIM_OUTPUT_TA1 | HRTIM_OUTPUT_TA2 | HRTIM_OUTPUT_TC1 | HRTIM_OUTPUT_TC2)); //enable hrtimer A en C outputs
 
  HAL_DAC_Start(&hdac1, DAC_CHANNEL_1); //enable DAC output 1, this sends the scaled ADC value to pin PA4
 
  HAL_ADC_Start_IT(&hadc3); //enable ADC
 
 
 
  HAL_TIM_OC_Start(&htim2, TIM_CHANNEL_1);//start TIM2 that is used for data trigger and use polling not interrupt
 
  //HAL_ADC_Start_DMA(&hadc3, (uint32_t *)adc_array, (uint32_t)1);
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
 
		if(check_timer_interrupt_flag_set(&htim2,OC1_FLAG)) //check if OC_INTERRUPT has passed
		{
		HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_9); // toggle pin E9
		send_info_uart();
		}
  }
  /* USER CODE END 3 */
}

void send_info_uart(void)
{
	HAL_UART_Transmit(&huart4,(uint8_t *)aTxBuffer, sizeof(aTxBuffer),500)
 
}
 
uint8_t check_timer_interrupt_flag_set(TIM_HandleTypeDef *handle,uint32_t number)
{
if(handle->Instance->SR & number)
	{
	handle->Instance->SR ^= number;
	return 1;
	}
else
	{return 0;}
 
}
 
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef *hadc)
{
	HRTIM_CompareCfgTypeDef timera_comp,adc_comp;
	//adc_converted_value=adc_array[0];
	adc_converted_value = HAL_ADC_GetValue(&hadc3);
 
	float temp = adc_converted_value*0.00763;
 
 
	timera_comp.CompareValue = (uint16_t) temp;
	if(timera_comp.CompareValue<3){timera_comp.CompareValue=3;}
	HAL_HRTIM_WaveformCompareConfig(&hhrtim, HRTIM_TIMERINDEX_TIMER_A, HRTIM_COMPAREUNIT_1, &timera_comp);
	HAL_HRTIM_WaveformCompareConfig(&hhrtim, HRTIM_TIMERINDEX_TIMER_C, HRTIM_COMPAREUNIT_1, &timera_comp);
	adc_comp.CompareValue = (uint16_t) (temp / 2 );
	HAL_HRTIM_WaveformCompareConfig(&hhrtim, HRTIM_TIMERINDEX_TIMER_A, HRTIM_COMPAREUNIT_2, &adc_comp);
 
	HAL_DAC_SetValue(&hdac1,DAC_CHANNEL_1,DAC_ALIGN_12B_R,(adc_converted_value*0.0625));
	//HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_9);
 
 
}

[S.Ma]

The SW architecture looks weird.

First, don't use float inside an interrupt (callback), you can most of the time use a int32_t temp_x100000 = adc_converted_Value *763;

Then in the main loop you look for a Timer status flag. Where will it be cleared for next time it's going to be tested?

USART send or receive take time (115200bps = 100usec per byte, so if core runs at 80MHz, that's 8000 cycles... significant.

[MVan.16]

The check_timer_interrupt_flag_set function resets the flag. It seems i found the problem. I use timer a compare 2 to trigger my adc. This has to do with current meas. I want to adjust this every time i trigger so that when i the adc samples it is always in the middle of the duty cycle. When i do this my adc loses its trigger. When i put this in comment there is no problem. I just need to find a solid way to make sure the adc triggers every cycle in the middle of the duty cycle.

[MVan.16]

solved the problem by making the variable in the interrupt static.

[MVan.16]

solved the problem by making the variable in the interrupt static.Now it does what it should do.