F411 Nucleo Board ADC Issues

[HDaji.1]

I tried to use ADC in F411 to read two ADC inputs.

My hardware is a F411-Nucleo board; my IDE is CubeIDE.

The followings are my ADC settings in IDE:

• I use 2 channels in ADC1 (IN1, IN4)
• I also use DMA to obtain ADC results.

I use 

volatile uint16_t adc_reading[2]

to store the 2 readings.

Here is the code in the while loop of main.c

  while (1)
  {
	adc_read_complete = 0;
	HAL_ADC_Start_DMA(&hadc1, (uint32_t *)adc_reading, adc_ch_cnt);
	while(adc_read_complete == 0);
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
        sprintf(uart2_str, "\t%d     %d\n", adc_reading[0], adc_reading[1]);
	HAL_UART_Transmit(&huart2, (uint8_t *)uart2_str, strlen(uart2_str), 999);
	HAL_Delay(2500);
  }

adc_ch_cnt is 2.

I have two problems:

1. Only adc_reading[0] has a valid reading; adc_reading[1] is always 0; even I define it as uint32_t variable and change data length as WORD. That valid reading corresponds to the voltage applied to IN4/PA4.
2. The valid reading is only 8 bits long, instead of 12 bits; meaning value is 254~255  when I applied 3.3v to PA4 pin.

[GwenoleB]

Hello @HDaji.1,

Could you please try again by using EOC flag defined as 'EOC flag at the end of all conversion' instead of 'single channel conversion'?

Best Regards,

Gwénolé

[HDaji.1 · Accepted solution]

Hi @GwenoleB

Still does not work.

However, I notice that there is something I did not do quite right.

I am testing on an F411RE-Nucleo board, while I select F411RETx in the board selection. Is it the cause?

I will retry from the board selection.

[HDaji.1]

I did again with Nucleo-F411RE in board selection step.

Now it's working.

However, the root cause is not clear to me.