Posted on February 01, 2018 at 09:07
Good Day
If I call:
HAL_ADC_Start_DMA(&hadc1, (uint32_t*)getADCBuffer, adcBufferLength); //uint16_t getADCBuffer[adcBufferLength] and adcBufferLenght is defined as 1000�?
and then call:
HAL_ADC_Stop_DMA(&hadc1);�?
before the 'adcBufferLength' was reached, how can I check how many new bytes I have in my getADCBuffer for every iteration of the code?
Can I do this:
adcNumSamplesCaptured = (adcBufferLength - (uint16_t)(DMA1_Channel1->CNDTR));�?
where obviously DMA1_Channel1 is associated with the ADC Configuration.
In normal mode, will CNDTR return to 'adcBufferLength' automatically every time? The Reference Manual for my MCU says:
'
If the channel is configured in non-circular mode, no DMA request is served after the last
transfer (that is once the number of data items to be transferred has reached zero). In orderto reload a new number of data items to be transferred into the DMA_CNDTRx register, theDMA channel must be disabled.'
I should never reach '0' items left to transfer,is there something that I must do?
ShouldI call 'CLEAR_BIT(DMA1_Channel1->CCR,DMA_CCR_EN);' before calling
'HAL_ADC_Start_DMA(&hadc1, (uint32_t*)getADCBuffer, adcBufferLength);' ?
I find that sometimes 'adcNumSamplesCaptured is larger than the number of non-zero bytes in 'getADCBuffer', and can't quite figure out why.
My ADC DMA Configuration:
/* ADC1 DMA Init */
/* ADC1 Init */
hdma_adc1.Instance = DMA1_Channel1;
hdma_adc1.Init.Request = DMA_REQUEST_0;
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_NORMAL;
hdma_adc1.Init.Priority = DMA_PRIORITY_HIGH;
if (HAL_DMA_Init(&hdma_adc1) != HAL_OK)
{
_Error_Handler(__FILE__, __LINE__);
}
__HAL_LINKDMA(adcHandle,DMA_Handle,hdma_adc1);
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Kind Regards
#dma #dma-adc #dma-normal #adc #stm32-adc
