I am using the STM IoT Kit Node and have a current sensor (voltage output) connected to the ADC.
I can read the current through the ADC by reading the counts and doing the correct conversion. But I'm trying to read the instantaneous peak current (the sensor is on a line driving a motor).
So the peak current draw when the motor is activated goes high (8-9 amps) for a split second, before settling down to the steady state value of around 4 amps.
I have the ADC set up using DMA and have the HAL_ADC_ConvHalfCpltCallback and HAL_ADC_ConvCpltCallback functions implemented. When they are called they search their respective half of the ADC array to find the max value. As I said though, this seems to be missing the instantaneous peak current.
I'm not sure if the DMA / ADC is missing the value because it isn't sampling fast enough and misses it, or if my processing of the data is taking too long...
Attached is my init code and interrupt code
static void MX_ADC1_Init(void)
{
ADC_ChannelConfTypeDef sConfig = {0};
/** Common config */
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;
hadc1.Init.EOCSelection = ADC_EOC_SEQ_CONV;
hadc1.Init.LowPowerAutoWait = DISABLE;
hadc1.Init.ContinuousConvMode = ENABLE;
hadc1.Init.NbrOfConversion = 3;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.DMAContinuousRequests = ENABLE;
hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
hadc1.Init.OversamplingMode = DISABLE;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler(__LINE__, __FILE__);
}
/** Configure Regular Channel */
sConfig.Channel = ADC_CHANNEL_1;
sConfig.Rank = ADC_REGULAR_RANK_1;
sConfig.SamplingTime = ADC_SAMPLETIME_12CYCLES_5;
sConfig.SingleDiff = ADC_SINGLE_ENDED;
sConfig.OffsetNumber = ADC_OFFSET_NONE;
sConfig.Offset = 0;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler(__LINE__, __FILE__);
}
/** Configure Regular Channel */
sConfig.Channel = ADC_CHANNEL_2;
sConfig.Rank = ADC_REGULAR_RANK_2;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler(__LINE__, __FILE__);
}
/** Configure Regular Channel */
sConfig.Channel = ADC_CHANNEL_3;
sConfig.Rank = ADC_REGULAR_RANK_3;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler(__LINE__, __FILE__);
}
while((HAL_ADCEx_Calibration_Start(&hadc1, ADC_SINGLE_ENDED)!= HAL_OK))
{
vTaskDelay(10);
}
// -- Enables ADC DMA request
if (HAL_ADC_Start_DMA(&hadc1, (uint32_t*)ADC1ConvertedValues, DMA_BUFFER_SIZE_PER_ADC * NUM_ADC_MEASUREMENTS) != HAL_OK)
{
Error_Handler(__LINE__, __FILE__);
}
HAL_NVIC_SetPriority(DMA1_Channel1_IRQn, configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY, 0);
HAL_NVIC_EnableIRQ(DMA1_Channel1_IRQn);
}
void MaxAdcVal(int start, int end, int step)
{
BaseType_t xHigherPriorityTaskWoken = pdFALSE;
xSemaphoreTakeFromISR(maxCurrentMeasurementSemaphore, &xHigherPriorityTaskWoken);
for(int i = start; i < end; i += step)
{
maxCurrentAdcCount = max_uint32(maxCurrentAdcCount, ADC1ConvertedValues[i]);
}
xSemaphoreGiveFromISR(maxCurrentMeasurementSemaphore, &xHigherPriorityTaskWoken);
portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
}
// Called when first half of buffer is filled
void HAL_ADC_ConvHalfCpltCallback(ADC_HandleTypeDef* hadc)
{
MaxAdcVal(CURRENT_SENSOR_ADC_RANK - 1,DMA_BUFFER_SIZE_PER_ADC * NUM_ADC_MEASUREMENTS / 2, NUM_ADC_MEASUREMENTS);
}
// Called when buffer is completely filled
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc)
{
MaxAdcVal(currentAdcDmaSecondHalfStartIndex,DMA_BUFFER_SIZE_PER_ADC * NUM_ADC_MEASUREMENTS, NUM_ADC_MEASUREMENTS);
}
