STM32 ADC DMA Double/Multi Buffer example

Question

According to documentation, many of STM32's supports DMA in Double-Buffer (or also known as Multi-Buffer) mode. In HAL, there are two functions for this feature: HAL_DMAEx_MultiBufferStart and HAL_DMAEx_MultiBufferStart_IT in stm32xxxx_hal_adc_ex file. But in any SDK (H7, F7, F4 etc.), there are not single example of usage of those two functions. How to get this double-buffering DMA working together with ADC?

Chris_B Chris_B · Accepted Answer · 2021-01-30T21:28:12

I never used the functions you mentioned for double buffer technique. I simply create a buffer, which has double the size of a "normal" buffer and use the DMA Callback functions HAL_ADC_ConvCpltCallback and HAL_ADC_ConvHalfCpltCallback for the decision which half of the buffer needs to be processed.

On an "HAL_ADC_ConvCpltCallback" Interrupt the upper half of the Double Buffer is processed while the ADC is writing its data in the lower half and vice versa ...

So: if I want e.g. to process my data in blocks of 100 samples, I create a buffer with 200 samples

uint32_t ADC_DMABuffer[ADC_DMABufferSize * 2];

and start the ADC with

HAL_ADC_Start_DMA(&hadc1, ADC_DMABuffer, ((uint32_t)(ADC_DMABufferSize * 2)));  // Double Buffer

For processing the data in the lower half the start pointer is

ADC_DMABuffer[0]

for the upper half the start pointer is

ADC_DMABuffer[ADC_DMABufferSize]

and the count of data, that need to be processed is of course "ADC_DMABufferSize" ...

STM32 ADC DMA Double/Multi Buffer example

1 Answers