Hello Everyone,
I am using the stm32h7 to sample 4 channels from adc1 using the DMA.
I am using circular mode with half word size. I start the dma and let it fill up a memory buffer:
volatile uint16_t adcInsDMA[4*ADCBLOCKSIZE] = {0};
HAL_StatusTypeDef status = HAL_ADC_Start_DMA(&hadc1, (uint32_t*)&adcInsDMA[0], 4*ADCBLOCKSIZE);
This works, however It looks like I am only getting 6bits of resolution. and not 16.
I consistently get only 63 distinct value no matter when I sample, or what the speed is of the incoming signal etc.
Here are my initialization settings generated by CUBEIDE:
/* ADC1 init function */
void MX_ADC1_Init(void)
{
ADC_MultiModeTypeDef multimode = {0};
ADC_ChannelConfTypeDef sConfig = {0};
/** Common config
*/
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
hadc1.Init.Resolution = ADC_RESOLUTION_16B;
hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;
hadc1.Init.EOCSelection = ADC_EOC_SEQ_CONV;
hadc1.Init.LowPowerAutoWait = DISABLE;
hadc1.Init.ContinuousConvMode = ENABLE;
hadc1.Init.NbrOfConversion = 4;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DMA_CIRCULAR;
hadc1.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
hadc1.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
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_3;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_32CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
sConfig.OffsetSignedSaturation = DISABLE;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_4;
sConfig.Rank = ADC_REGULAR_RANK_2;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_7;
sConfig.Rank = ADC_REGULAR_RANK_3;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure Regular Channel
*/
sConfig.Channel = ADC_CHANNEL_8;
sConfig.Rank = ADC_REGULAR_RANK_4;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
}
void HAL_ADC_MspInit(ADC_HandleTypeDef* adcHandle)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(adcHandle->Instance==ADC1)
{
/* USER CODE BEGIN ADC1_MspInit 0 */
/* USER CODE END ADC1_MspInit 0 */
/* ADC1 clock enable */
__HAL_RCC_ADC12_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOC_CLK_ENABLE();
/**ADC1 GPIO Configuration
PA6 ------> ADC1_INP3
PA7 ------> ADC1_INN3
PA7 ------> ADC1_INP7
PC4 ------> ADC1_INP4
PC5 ------> ADC1_INN4
PC5 ------> ADC1_INP8
*/
GPIO_InitStruct.Pin = IN_SIG_1_ADC_Pin|IN_SIG_2_ADC_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
GPIO_InitStruct.Pin = IN_SIG_3_ADC_Pin|IN_SIG_4_ADC_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
/* ADC1 DMA Init */
/* ADC1 Init */
hdma_adc1.Instance = DMA1_Stream0;
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_MDATAALIGN_HALFWORD;
hdma_adc1.Init.Mode = DMA_CIRCULAR;
hdma_adc1.Init.Priority = DMA_PRIORITY_LOW;
hdma_adc1.Init.FIFOMode = DMA_FIFOMODE_ENABLE;
hdma_adc1.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL;
hdma_adc1.Init.MemBurst = DMA_MBURST_SINGLE;
hdma_adc1.Init.PeriphBurst = DMA_PBURST_SINGLE;
if (HAL_DMA_Init(&hdma_adc1) != HAL_OK)
{
Error_Handler();
}
__HAL_LINKDMA(adcHandle,DMA_Handle,hdma_adc1);
/* USER CODE BEGIN ADC1_MspInit 1 */
/* USER CODE END ADC1_MspInit 1 */
}
}
void HAL_ADC_MspDeInit(ADC_HandleTypeDef* adcHandle)
{
if(adcHandle->Instance==ADC1)
{
/* USER CODE BEGIN ADC1_MspDeInit 0 */
/* USER CODE END ADC1_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_ADC12_CLK_DISABLE();
/**ADC1 GPIO Configuration
PA6 ------> ADC1_INP3
PA7 ------> ADC1_INN3
PA7 ------> ADC1_INP7
PC4 ------> ADC1_INP4
PC5 ------> ADC1_INN4
PC5 ------> ADC1_INP8
*/
HAL_GPIO_DeInit(GPIOA, IN_SIG_1_ADC_Pin|IN_SIG_2_ADC_Pin);
HAL_GPIO_DeInit(GPIOC, IN_SIG_3_ADC_Pin|IN_SIG_4_ADC_Pin);
/* ADC1 DMA DeInit */
HAL_DMA_DeInit(adcHandle->DMA_Handle);
/* USER CODE BEGIN ADC1_MspDeInit 1 */
/* USER CODE END ADC1_MspDeInit 1 */
}
}Any Ideas on what I could be missing would be appreaciated!
Thanks,
Trevor
Hi JW,
Thanks for your reply,
I have VREF+ connected to 3.3v, same line as all VDD pins and VDDA.
I have VSSA/VREF- (Pin 31) connected to GND on same line as other VSS pins.
I am curious why would an unstable/moving reference would cause a bit precision error? does the hardware have/go into a "safety" mode?
weird thing is, I have seen the ADC work with LSB on a similar previous iteration of my board (with a similar power scheme). I am beginning to think I got a bad batch, I am usually wrong about that though.
