Question
ADC using DMA works in 8-bit mode even though a resolution of 12-bit is activated.
Hello,
I would like to use an ADC using DMA in 12-bit mode.
Unfortuntaly, the adc value is only 8-bit which doesn't match with my configuration. I've already tried to solve the problem by trying the solution proposed here: https://community.st.com/t5/stm32-mcus-products/why-would-an-adc-sample-in-8-bit-mode-when-dma-is-used-but-when/m-p/197276/highlight/true#M42484
But it didn't work in my case.
Here's my source code for dma and adc. I am not working with the cubeIDE anymore, that's why my configuration functions look different than the auto-generated init-functions of the IDE. The weird thing is that the same configuration is working in the CubeIDE... (so maybe it's a structual problem in my configuration)
ADC_HandleTypeDef hadc1;
DMA_HandleTypeDef hdma_adc1;
uint16_t buffer;
uint16_t adc_value;
void DMA1_Channel1_IRQHandler(void) {
HAL_DMA_IRQHandler(&hdma_adc1);
}
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) {
adc_value = buffer; //store value
}
void adcInit(void) {
GPIO_InitTypeDef GPIO_InitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
ADC_MultiModeTypeDef multimode = {0};
ADC_ChannelConfTypeDef sConfig = {0};
__HAL_RCC_ADC12_CLK_ENABLE();
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC12;
PeriphClkInit.Adc12ClockSelection = RCC_ADC12CLKSOURCE_SYSCLK;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK) {
Error_Handler();
}
__HAL_RCC_GPIOC_CLK_ENABLE();
/**ADC1 GPIO Configuration
PC2 ------> ADC1_IN8
*/
GPIO_InitStruct.Pin = GPIO_PIN_2;
GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.GainCompensation = 0;
hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
hadc1.Init.LowPowerAutoWait = DISABLE;
hadc1.Init.ContinuousConvMode = DISABLE;
hadc1.Init.NbrOfConversion = 1;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.DMAContinuousRequests = DISABLE;
hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
hadc1.Init.OversamplingMode = DISABLE;
if (HAL_ADC_Init(&hadc1) != HAL_OK) {
Error_Handler();
}
/** Configure the ADC multi-mode */
multimode.Mode = ADC_MODE_INDEPENDENT;
if (HAL_ADCEx_MultiModeConfigChannel(&hadc1, &multimode) != HAL_OK) {
Error_Handler();
}
/** Configure Regular Channel */
sConfig.Channel = ADC_CHANNEL_8;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_2CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK) {
Error_Handler();
}
}void dmaInit() {
/* DMA controller clock enable */
__HAL_RCC_DMAMUX1_CLK_ENABLE();
__HAL_RCC_DMA1_CLK_ENABLE();
/* DMA interrupt init */
/* DMA1_Channel1_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
//HAL_DMA_IRQHandler(&hdma_adc1);
/* ADC1 Init */
hdma_adc1.Instance = DMA1_Channel1;
hdma_adc1.Init.Request = DMA_REQUEST_ADC1;
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_PDATAALIGN_HALFWORD;
hdma_adc1.Init.Mode = DMA_CIRCULAR;
hdma_adc1.Init.Priority = DMA_PRIORITY_HIGH;
if (HAL_DMA_Init(&hdma_adc1) != HAL_OK) {
Error_Handler();
}
__HAL_LINKDMA(&hadc1,DMA_Handle,hdma_adc1);
}
void initProcess(void) {
dmaInit();
adcInit();
HAL_ADC_Start_DMA(&hadc1, &buffer, 1);
}