STM32L496 ADC with HAL and DMA: only one byte updated in results buffer

Question

In the context of an STM32L496 project, I've setup the ADC with two input channels as follows

And the DMA like this:

I'm using the following code to start the conversion and display the results:

adc_done = 0;
HAL_ADC_Start_DMA(&hadc1, (uint32_t*) adc_results, 2);

while (!adc_done) {
  HAL_Delay(1);
}

for (int i = 0; i < 2; i++) {
  printf("ADC%d: %.4X", i + 1, adc_results[i]);
}

HAL_ADC_Stop_DMA(&hadc1);

For some reason, it seems that only the very first byte of my adc_results buffer gets updated. All the other bytes remain at their default values, which I've set to 0xAA.

What could be the reason for this? I'm suspecting that this is more of a DMA than an ADC issue.

Answer 1

I was having a similar issue, I was able to fix it by setting DMA Continuous Requests to Enabled.