ADC reading error

[vasudev]

I am using stm32f334r8 for digital power control. I have configured ADC using cube mx Lower level. ADC reads 0 for 40mv input even though ADC is configured to 12bit and 181  sampling cycles. I also tried calibrating ADC before conversion is started. The ADC channel is fed by low output impedence opamp. I need your help to solve this issue. Also I am not sure if the calibration is happening or not. 

 LL_ADC_Disable(ADC1);
LL_ADC_StartCalibration(ADC1,LL_ADC_SINGLE_ENDED);
LL_ADC_DELAY_CALIB_ENABLE_ADC_CYCLES;
LL_ADC_Enable(ADC1);
LL_ADC_DELAY_VREFINT_STAB_US;
if(LL_ADC_IsActiveFlag_ADRDY(ADC1)==1){
//LL_ADC_EnableIT_EOSMP(ADC1);
LL_ADC_EnableIT_EOS(ADC1);
LL_HRTIM_EnableOutput(HRTIM1,LL_HRTIM_OUTPUT_TA1);
LL_HRTIM_TIM_CounterEnable(HRTIM1,LL_HRTIM_TIMER_A);
// LL_HRTIM_EnableIT_CMP2(HRTIM1, LL_HRTIM_TIMER_A);
LL_DMA_DisableChannel(DMA1,LL_DMA_CHANNEL_1);
LL_ADC_REG_SetDMATransfer(ADC1,LL_ADC_REG_DMA_TRANSFER_UNLIMITED);
LL_DMA_SetMemoryAddress(DMA1, LL_DMA_CHANNEL_1,(uint32_t)(&adc));
LL_DMA_SetPeriphAddress(DMA1,LL_DMA_CHANNEL_1 ,(uint32_t)(&(ADC1->DR)));
LL_DMA_SetDataLength(DMA1, LL_DMA_CHANNEL_1,2);
LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_1);
LL_ADC_REG_StartConversion(ADC1);
}

[TDK]

> Also I am not sure if the calibration is happening or not. 

The ADC must be calibrated before it is used.

Lots of other relevant code isn't shown here such as configuration of the channel and pin.

Perhaps go off of a working ADC example from the CubeMX repository.

[vasudev]

I will share the code. 

 

include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */
int pwmoutput,adc=0;
/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);
static void MX_HRTIM1_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void ADC1_2_IRQHandler(void)
{
//LL_GPIO_SetOutputPin(GPIOC,LL_GPIO_PIN_8);
adc= LL_ADC_REG_ReadConversionData12(ADC1);
LL_ADC_ClearFlag_EOC(ADC1);
//LL_GPIO_ResetOutputPin(GPIOC,LL_GPIO_PIN_8);

}
/* USER CODE END 0 */

/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */

/* USER CODE END 1 */

/* MCU Configuration--------------------------------------------------------*/

/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();

/* USER CODE BEGIN Init */

/* USER CODE END Init */

/* Configure the system clock */
SystemClock_Config();

/* USER CODE BEGIN SysInit */

/* USER CODE END SysInit */

/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_ADC1_Init();
MX_HRTIM1_Init();
/* USER CODE BEGIN 2 */
LL_HRTIM_EnableOutput(HRTIM1,LL_HRTIM_OUTPUT_TA1);
LL_HRTIM_TIM_CounterEnable(HRTIM1,LL_HRTIM_TIMER_A);
LL_ADC_Disable(ADC1);
LL_ADC_StartCalibration(ADC1,LL_ADC_SINGLE_ENDED);
LL_ADC_DELAY_CALIB_ENABLE_ADC_CYCLES;
LL_ADC_Enable(ADC1);
LL_ADC_DELAY_VREFINT_STAB_US;
if(LL_ADC_IsActiveFlag_ADRDY(ADC1)==1){
//LL_ADC_EnableIT_EOSMP(ADC1);
LL_ADC_EnableIT_EOC(ADC1);
LL_ADC_REG_StartConversion(ADC1);
}
/* USER CODE END 2 */

/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{

/* USER CODE END WHILE */

/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}

/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}

/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_HRTIM1|RCC_PERIPHCLK_ADC12;
PeriphClkInit.Adc12ClockSelection = RCC_ADC12PLLCLK_DIV1;
PeriphClkInit.Hrtim1ClockSelection = RCC_HRTIM1CLK_PLLCLK;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
}

/**
* @brief ADC1 Initialization Function
* @PAram None
* @retval None
*/
static void MX_ADC1_Init(void)
{

/* USER CODE BEGIN ADC1_Init 0 */

/* USER CODE END ADC1_Init 0 */

LL_ADC_InitTypeDef ADC_InitStruct = {0};
LL_ADC_REG_InitTypeDef ADC_REG_InitStruct = {0};
LL_ADC_CommonInitTypeDef ADC_CommonInitStruct = {0};

LL_GPIO_InitTypeDef GPIO_InitStruct = {0};

/* Peripheral clock enable */
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_ADC12);

LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
/**ADC1 GPIO Configuration
PA0 ------> ADC1_IN1
*/
GPIO_InitStruct.Pin = LL_GPIO_PIN_0;
GPIO_InitStruct.Mode = LL_GPIO_MODE_ANALOG;
GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
LL_GPIO_Init(GPIOA, &GPIO_InitStruct);

/* ADC1 interrupt Init */
NVIC_SetPriority(ADC1_2_IRQn, NVIC_EncodePriority(NVIC_GetPriorityGrouping(),0, 0));
NVIC_EnableIRQ(ADC1_2_IRQn);

/* USER CODE BEGIN ADC1_Init 1 */

/* USER CODE END ADC1_Init 1 */

/** Common config
*/
ADC_InitStruct.Resolution = LL_ADC_RESOLUTION_12B;
ADC_InitStruct.DataAlignment = LL_ADC_DATA_ALIGN_RIGHT;
ADC_InitStruct.LowPowerMode = LL_ADC_LP_MODE_NONE;
LL_ADC_Init(ADC1, &ADC_InitStruct);
ADC_REG_InitStruct.TriggerSource = LL_ADC_REG_TRIG_EXT_HRTIM_TRG1;
ADC_REG_InitStruct.SequencerLength = LL_ADC_REG_SEQ_SCAN_DISABLE;
ADC_REG_InitStruct.SequencerDiscont = LL_ADC_REG_SEQ_DISCONT_DISABLE;
ADC_REG_InitStruct.ContinuousMode = LL_ADC_REG_CONV_SINGLE;
ADC_REG_InitStruct.DMATransfer = LL_ADC_REG_DMA_TRANSFER_LIMITED;
ADC_REG_InitStruct.Overrun = LL_ADC_REG_OVR_DATA_OVERWRITTEN;
LL_ADC_REG_Init(ADC1, &ADC_REG_InitStruct);
ADC_CommonInitStruct.CommonClock = LL_ADC_CLOCK_ASYNC_DIV1;
ADC_CommonInitStruct.Multimode = LL_ADC_MULTI_INDEPENDENT;
LL_ADC_CommonInit(__LL_ADC_COMMON_INSTANCE(ADC1), &ADC_CommonInitStruct);
LL_ADC_REG_SetTriggerEdge(ADC1, LL_ADC_REG_TRIG_EXT_RISING);

/* Enable ADC internal voltage regulator */
LL_ADC_EnableInternalRegulator(ADC1);
/* Delay for ADC internal voltage regulator stabilization. */
/* Compute number of CPU cycles to wait for, from delay in us. */
/* Note: Variable divided by 2 to compensate partially */
/* CPU processing cycles (depends on compilation optimization). */
/* Note: If system core clock frequency is below 200kHz, wait time */
/* is only a few CPU processing cycles. */
uint32_t wait_loop_index;
wait_loop_index = ((LL_ADC_DELAY_INTERNAL_REGUL_STAB_US * (SystemCoreClock / (100000 * 2))) / 10);
while(wait_loop_index != 0)
{
wait_loop_index--;
}

/** Configure Regular Channel
*/
LL_ADC_REG_SetSequencerRanks(ADC1, LL_ADC_REG_RANK_1, LL_ADC_CHANNEL_1);
LL_ADC_SetChannelSamplingTime(ADC1, LL_ADC_CHANNEL_1, LL_ADC_SAMPLINGTIME_1CYCLE_5);
LL_ADC_SetChannelSingleDiff(ADC1, LL_ADC_CHANNEL_1, LL_ADC_SINGLE_ENDED);
/* USER CODE BEGIN ADC1_Init 2 */

/* USER CODE END ADC1_Init 2 */

}

/**
* @brief HRTIM1 Initialization Function
* @PAram None
* @retval None
*/
static void MX_HRTIM1_Init(void)
{

/* USER CODE BEGIN HRTIM1_Init 0 */

/* USER CODE END HRTIM1_Init 0 */

LL_GPIO_InitTypeDef GPIO_InitStruct = {0};

/* Peripheral clock enable */
LL_APB2_GRP1_EnableClock(LL_APB2_GRP1_PERIPH_HRTIM1);

/* HRTIM1 interrupt Init */
NVIC_SetPriority(HRTIM1_TIMA_IRQn, NVIC_EncodePriority(NVIC_GetPriorityGrouping(),0, 0));
NVIC_EnableIRQ(HRTIM1_TIMA_IRQn);

/* USER CODE BEGIN HRTIM1_Init 1 */

/* USER CODE END HRTIM1_Init 1 */
LL_HRTIM_ConfigDLLCalibration(HRTIM1, LL_HRTIM_DLLCALIBRATION_MODE_CONTINUOUS, LL_HRTIM_DLLCALIBRATION_RATE_14);

/* Poll for DLL end of calibration */
#if (USE_TIMEOUT == 1)
uint32_t Timeout = 10; /* Timeout Initialization */
#endif /*USE_TIMEOUT*/

while(LL_HRTIM_IsActiveFlag_DLLRDY(HRTIM1) == RESET){
#if (USE_TIMEOUT == 1)
if (LL_SYSTICK_IsActiveCounterFlag()) /* Check Systick counter flag to decrement the time-out value */
{
if(Timeout-- == 0)
{
Error_Handler(); /* error management */
}
}
#endif /* USE_TIMEOUT */
}

LL_HRTIM_ConfigADCTrig(HRTIM1, LL_HRTIM_ADCTRIG_1, LL_HRTIM_ADCTRIG_UPDATE_TIMER_A, LL_HRTIM_ADCTRIG_SRC13_TIMACMP2);
LL_HRTIM_TIM_SetPrescaler(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_PRESCALERRATIO_MUL32);
LL_HRTIM_TIM_SetCounterMode(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_MODE_CONTINUOUS);
LL_HRTIM_TIM_SetPeriod(HRTIM1, LL_HRTIM_TIMER_A, 65000);
LL_HRTIM_TIM_SetRepetition(HRTIM1, LL_HRTIM_TIMER_A, 0x00);
LL_HRTIM_TIM_SetDACTrig(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_DACTRIG_NONE);
LL_HRTIM_TIM_DisableHalfMode(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_DisableStartOnSync(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_DisableResetOnSync(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_EnablePreload(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_SetUpdateGating(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_UPDATEGATING_INDEPENDENT);
LL_HRTIM_TIM_SetUpdateTrig(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_UPDATETRIG_TIMER_A|LL_HRTIM_UPDATETRIG_REPETITION);
LL_HRTIM_TIM_SetResetTrig(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_RESETTRIG_UPDATE);
LL_HRTIM_TIM_DisablePushPullMode(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_DisableDeadTime(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_SetBurstModeOption(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_BURSTMODE_MAINTAINCLOCK);
LL_HRTIM_ForceUpdate(HRTIM1, LL_HRTIM_TIMER_A);
LL_HRTIM_TIM_SetCompare1(HRTIM1, LL_HRTIM_TIMER_A, 1000);
LL_HRTIM_TIM_SetCompare2(HRTIM1, LL_HRTIM_TIMER_A, 100);
LL_HRTIM_TIM_SetCompareMode(HRTIM1, LL_HRTIM_TIMER_A, LL_HRTIM_COMPAREUNIT_2, LL_HRTIM_COMPAREMODE_REGULAR);
LL_HRTIM_OUT_SetPolarity(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_OUT_POSITIVE_POLARITY);
LL_HRTIM_OUT_SetOutputSetSrc(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_CROSSBAR_TIMPER);
LL_HRTIM_OUT_SetOutputResetSrc(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_CROSSBAR_TIMCMP1);
LL_HRTIM_OUT_SetIdleMode(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_OUT_NO_IDLE);
LL_HRTIM_OUT_SetIdleLevel(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_OUT_IDLELEVEL_INACTIVE);
LL_HRTIM_OUT_SetFaultState(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_OUT_FAULTSTATE_NO_ACTION);
LL_HRTIM_OUT_SetChopperMode(HRTIM1, LL_HRTIM_OUTPUT_TA1, LL_HRTIM_OUT_CHOPPERMODE_DISABLED);
/* USER CODE BEGIN HRTIM1_Init 2 */

/* USER CODE END HRTIM1_Init 2 */
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
/**HRTIM1 GPIO Configuration
PA8 ------> HRTIM1_CHA1
*/
GPIO_InitStruct.Pin = LL_GPIO_PIN_8;
GPIO_InitStruct.Mode = LL_GPIO_MODE_ALTERNATE;
GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
GPIO_InitStruct.Alternate = LL_GPIO_AF_13;
LL_GPIO_Init(GPIOA, &GPIO_InitStruct);

}

/**
* @brief GPIO Initialization Function
* @PAram None
* @retval None
*/
static void MX_GPIO_Init(void)
{
LL_EXTI_InitTypeDef EXTI_InitStruct = {0};
LL_GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

/* GPIO Ports Clock Enable */
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOC);
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOF);
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);
LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOB);

/**/
LL_GPIO_ResetOutputPin(LD2_GPIO_Port, LD2_Pin);

/**/
LL_GPIO_ResetOutputPin(GPIOC, LL_GPIO_PIN_8);

/**/
LL_SYSCFG_SetEXTISource(LL_SYSCFG_EXTI_PORTC, LL_SYSCFG_EXTI_LINE13);

/**/
LL_GPIO_SetPinPull(B1_GPIO_Port, B1_Pin, LL_GPIO_PULL_NO);

/**/
LL_GPIO_SetPinMode(B1_GPIO_Port, B1_Pin, LL_GPIO_MODE_INPUT);

/**/
EXTI_InitStruct.Line_0_31 = LL_EXTI_LINE_13;
EXTI_InitStruct.Line_32_63 = LL_EXTI_LINE_NONE;
EXTI_InitStruct.LineCommand = ENABLE;
EXTI_InitStruct.Mode = LL_EXTI_MODE_IT;
EXTI_InitStruct.Trigger = LL_EXTI_TRIGGER_FALLING;
LL_EXTI_Init(&EXTI_InitStruct);

/**/
GPIO_InitStruct.Pin = LD2_Pin;
GPIO_InitStruct.Mode = LL_GPIO_MODE_OUTPUT;
GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
LL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);

/**/
GPIO_InitStruct.Pin = LL_GPIO_PIN_8;
GPIO_InitStruct.Mode = LL_GPIO_MODE_OUTPUT;
GPIO_InitStruct.Speed = LL_GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.OutputType = LL_GPIO_OUTPUT_PUSHPULL;
GPIO_InitStruct.Pull = LL_GPIO_PULL_NO;
LL_GPIO_Init(GPIOC, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}

#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @PAram file: pointer to the source file name
* @PAram line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_