STM32F103 ADC + DMA multichannel, from FreeRTOS software timer. Continuous mode works. Manually triggering HAL_ADC_Start_DMA() return HAL_ERROR on ADC_Enable() on second call

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Posted on February 21, 2018 at 19:20

Hi,

I've successfully run a FreeRTOS program that use ADC + DMA in scan, continuous, circular mode and I successfully can average in HAL_ADC_ConvCpltCallback().

Now I'd still like to use DMA to fill a buffer of 3 channels x 8 conversions but I'd like to start the conversion from  a FreeRTOS software timer.

So I'd expect that I start the DMA from a software timer, once the hardware has finished it stops conversions and HAL_ADC_ConvCpltCallback() get called, I average results and wait another software timer restart the conversion.

I've tried to disable continuous mode, to run DMA in REGULAR mode vs CIRCULAR... but every time I try, the second time HAL_ADC_Start_DMA() get called I get an HAL_ERROR from ADC_Enable().

This works continuously if I just call HAL_ADC_Start_DMA() once.

uint16_t ADCraw[ADCSamples][ADCChannels];

    hadc1.Instance = ADC1;

    hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;    hadc1.Init.ContinuousConvMode = ENABLE;    hadc1.Init.DiscontinuousConvMode = DISABLE;    hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;    hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;    hadc1.Init.NbrOfConversion = 3;

        hdma_adc1.Instance = DMA1_Channel1;

        hdma_adc1.Init.Direction = DMA_PERIPH_TO_MEMORY;        hdma_adc1.Init.PeriphInc = DMA_PINC_DISABLE;        hdma_adc1.Init.MemInc = DMA_MINC_ENABLE;        hdma_adc1.Init.PeriphDataAlignment = DMA_PDATAALIGN_HALFWORD;        hdma_adc1.Init.MemDataAlignment = DMA_MDATAALIGN_HALFWORD;        hdma_adc1.Init.Mode = DMA_CIRCULAR;        hdma_adc1.Init.Priority = DMA_PRIORITY_LOW;

HAL_ADC_Start_DMA(&hadc1, (uint32_t*) ADCraw, ADCChannels * ADCSamples);

Thanks

#freertos #software-timer #stmf1 #continuous-conversion #dma #adc

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