ADC value not correct for ADC_CHANNEL_12
Hello,
I am using STM32F446 MCU. ADC chnanel 10 & ADC channel 12.
ADC ref voltage is 3.0V.
I am getting 0 count for 0v on ADC channel 10.
But I get ADC count value 87 for ADC channel 12. which calculates to 1 V.
what could be the issue?.
Reading is taken every 10ms.
Please find the ADC code below:
#define ADC_DMA_CHANNEL2 DMA_Channel_2
#define ADC_DMA_STREAM DMA2_Stream0void StartAnalogReadout_STM32f4(void)
{ static CAlarmRTC alarm(0, 10);DMA_InitTypeDef DMA_InitStruct;
ADC_CommonInitTypeDef ADC_CommonStruct; ADC_InitTypeDef ADC_InitStruct; GPIO_InitTypeDef GPIO_InitStruct; uint32 addr = (uint32)adc_buffer;/* System clocks configuration ---------------------------------------------*/
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOC, ENABLE); RCC_APB2PeriphClockCmd(/*RCC_APB2Periph_ADC1 |*/ RCC_APB2Periph_ADC3, ENABLE);/* GPIO configuration ------------------------------------------------------*/
// This is for revision P289Rev01c GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_2; GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AN; GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; GPIO_InitStruct.GPIO_Speed = GPIO_Speed_25MHz; GPIO_Init(GPIOC, &GPIO_InitStruct);/* DMA2 channel0 configuration ----------------------------------------------*/
// InitStructure(DMA_InitStruct); memset(&DMA_InitStruct,0,sizeof(DMA_InitStruct));DMA_InitStruct.DMA_Mode = DMA_Mode_Circular;
DMA_InitStruct.DMA_Channel = ADC_DMA_CHANNEL2; DMA_InitStruct.DMA_BufferSize = 2; DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable; DMA_InitStruct.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull; DMA_InitStruct.DMA_Memory0BaseAddr = (uint32)addr; DMA_InitStruct.DMA_MemoryBurst = DMA_MemoryBurst_Single; DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord; DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable; DMA_InitStruct.DMA_PeripheralBaseAddr = (uint32)&(ADC3->DR); DMA_InitStruct.DMA_PeripheralBurst = DMA_PeripheralBurst_Single; DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStruct.DMA_Priority = DMA_Priority_Low; DMA_Init(ADC_DMA_STREAM, &DMA_InitStruct);/* ADC1 configuration ------------------------------------------------------*/
ADC_CommonStruct.ADC_Mode = ADC_Mode_Independent; ADC_CommonStruct.ADC_Prescaler = ADC_Prescaler_Div8; ADC_CommonStruct.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled; ADC_CommonStruct.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles; ADC_CommonInit(&ADC_CommonStruct);ADC_InitStruct.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStruct.ADC_ScanConvMode = ENABLE; ADC_InitStruct.ADC_ContinuousConvMode = DISABLE; ADC_InitStruct.ADC_ExternalTrigConv = ADC_ExternalTrigConv_UNUSED; ADC_InitStruct.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None; ADC_InitStruct.ADC_DataAlign = ADC_DataAlign_Right; ADC_InitStruct.ADC_NbrOfConversion = 2;// ADC_Init(ADC1, &ADC_InitStruct); ADC_Init(ADC3, &ADC_InitStruct);/* ADC1 regular channel configuration */
// ADC_RegularChannelConfig(ADC1, ADC_Channel_1, 1, ADC_SampleTime_15Cycles);// ADC_RegularChannelConfig(ADC1, ADC_Channel_7, 2, ADC_SampleTime_15Cycles); ADC_RegularChannelConfig(ADC3, ADC_Channel_10, 1, ADC_SampleTime_15Cycles); ADC_RegularChannelConfig(ADC3, ADC_Channel_12, 2, ADC_SampleTime_15Cycles);/* Enable DMA request after last transfer (Single-ADC mode) */
// ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE); ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);/* Enable DMA2 channel0 */
DMA_Cmd(ADC_DMA_STREAM, ENABLE);/* Enable ADC1/3 DMA */
//ADC_DMACmd(ADC1, ENABLE); ADC_DMACmd(ADC3, ENABLE);/* Enable ADC1/3 */
// ADC_Cmd(ADC1, ENABLE); ADC_Cmd(ADC3, ENABLE);// while( !ADC_GetFlagStatus( ADC3, ADC_FLAG_OVR ) );
ADC_SoftwareStartConv(ADC3); /* Start the ADC trigger alarm */ alarm.SetAlarm(ADC_Conversion, NULL);// /*printdbg(DEBUG_SHOW_ALWAYS,*/trace_printf('StartAnalogReadout_STM32f4: ADC starting (%d ms)', cyg_current_millies());
}static void ADC_Conversion(void* data){ static uint8 index = 0;// Update ADC3.4/5
adc_values[0] = adc_buffer[s_idx_mapping[0]]; adc_values[1] = adc_buffer[s_idx_mapping[1]];// // Stop DMA transfer
ADC3->CR2 &= ~(uint32)ADC_CR2_DMA;// Overrun happens?
if (ADC3->SR & ADC_SR_OVR) { ADC3->SR &= ~ADC_SR_OVR; }// Trigger Conversion again
ADC3->CR2 |= (ADC_CR2_SWSTART | ADC_CR2_DMA);/*printdbg(DBG_SHOW_ALWAYS, 'ADC3: SR=%04Xh DMA=%04X (%u,%u)',
ADC3->SR, ADC_DMA_STREAM->CR, adc_buffer[0],adc_buffer[1]);*/}Regards
Pramod
