ADC value is not being read

[SIDDHARTH]

Hi all, I am new to stm32cube ide and this is my first project. I am currently working on stm32f103c8. I am taking the input from ADC1 pin PA0 which is connected to a potentiometer. I am controlling LEDs through a potentiometer and a button. The problem I am facing is that the value of the potentiometer is not being read. I have also shared the code below.

/* USER CODE BEGIN 0 */
uint32_t adcVal;
/* USER CODE END 0 */

 while (1)
 {
	 //HAL_ADC_Start_IT (&hadc1);
	 if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_1) == 0)
	 {
		 HAL_ADC_Start_IT(&hadc1);
		 if (adcVal > 2048)
		 {
			 HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
			 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);
		 }
		 else
		 {
			 HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_2);
			 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);
		 }
		 HAL_Delay(200);
		 //HAL_ADC_Start_IT (&hadc1);
	 }
	 else
	 {
		 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);
		 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);
	 }

/* USER CODE BEGIN 4 */
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
 adcVal = HAL_ADC_GetValue(&hadc1);
}

 

The problem I am facing is in the while loop part in the second if and else statement where I have given the commands to toggle respective LEDs. Only the else statement is being used. The value from hadc1 is not being compared.

if (adcVal > 2048)
		 {
			 HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
			 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);
		 }

This part does not seem to work. can someone please share as to where I am going wrong

[TDK]

Use polling and get the value as in the example here:

https://github.com/STMicroelectronics/STM32CubeF1/blob/e226c47ca625df6a36dedbbc3f588017e4d94a45/Drivers/BSP/STM32F1xx_Nucleo/stm32f1xx_nucleo.c#L819

 

You can use interrupts, but then you need to wait for the operation to complete before using the value. Your current code doesn't wait at all.

 

[SIDDHARTH]

Hi @TDK I did try as you suggested but the error still persists.

I have also shared the code with the modifications I made as you suggested through the link.

while (1)
 {
	 HAL_ADC_Start(&hadc1);
	 if (HAL_ADC_PollForConversion(&hadc1,10) != HAL_TIMEOUT)
	 {
		 adc_val = HAL_ADC_GetValue(&hadc1);
		 if ((adc_val>0) && (adc_val <2048))
		 {
			 HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
			 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);
		 }
		 else
		 {
			 HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_2);
			 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_SET);
		 }
		 return adc_val;
	 }
	 else
	 {
		 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, GPIO_PIN_RESET);
		 HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3, GPIO_PIN_RESET);
	 }