ADC->DMA on Keil STM32F400 board

[paul2]

Posted on June 30, 2014 at 10:27

Hi,

It seems that DMA is not working properly. Based on the code below I don't get ADC values on the DMA destination adres ''ADC_Raw'' When I check the ADC peripheral address (ADC3_RDR), I can see the analog values, so the ADC values are available for DMA. Why are the analog values not processed by DMA? Do I miss something? I'm using a Keil STM32F400 board.

/*----------------------------------------------------------------------------
* ADC_DMA
*---------------------------------------------------------------------------*/
#include ''ADC_DMA.h''
#include <
stm32f4xx.h
>
//====================================================================================
// Configuring TIM2 to trigger at 2kHz which is the ADC sampling rate
//====================================================================================
void TIM2_Config(void)
{
TIM_TimeBaseInitTypeDef TIM2_TimeBase;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
TIM_TimeBaseStructInit(&TIM2_TimeBase); 
TIM2_TimeBase.TIM_Period = (uint16_t)49; // Trigger = CK_CNT/(49+1) = 2kHz
TIM2_TimeBase.TIM_Prescaler = 420; // CK_CNT = 42MHz/420 = 100kHz
TIM2_TimeBase.TIM_ClockDivision = 0;
TIM2_TimeBase.TIM_CounterMode = TIM_CounterMode_Up; 
TIM_TimeBaseInit(TIM2, &TIM2_TimeBase);
TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
TIM_Cmd(TIM2, ENABLE);
}
//====================================================================================
// Configuring GPIO PD9 (for testing)
//====================================================================================
void GPIOH_Config(void)
{
GPIO_InitTypeDef gpio_H;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOH, ENABLE);
gpio_H.GPIO_Mode = GPIO_Mode_OUT;
gpio_H.GPIO_OType = GPIO_OType_PP;
gpio_H.GPIO_Pin = GPIO_Pin_3;
gpio_H.GPIO_PuPd = GPIO_PuPd_NOPULL;
gpio_H.GPIO_Speed = GPIO_Medium_Speed;
GPIO_Init(GPIOH, &gpio_H);
}
//====================================================================================
// Configuring ADC with DMA
//====================================================================================
void ADC_Config(void)
{
ADC_InitTypeDef ADC_INIT;
ADC_CommonInitTypeDef ADC_COMMON;
DMA_InitTypeDef DMA_INIT;
GPIO_InitTypeDef gpio_F;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOF, ENABLE); //Enable DMA2 clock 
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE); //Enable ADC3 clock
DMA_INIT.DMA_Channel = DMA_Channel_0; 
DMA_INIT.DMA_PeripheralBaseAddr = (uint32_t)ADC3_RDR; //0x4001224C
DMA_INIT.DMA_Memory0BaseAddr = (uint32_t)&ADC_Raw[0]; 
DMA_INIT.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_INIT.DMA_BufferSize = NS;
DMA_INIT.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_INIT.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_INIT.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_INIT.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_INIT.DMA_Mode = DMA_Mode_Circular;
DMA_INIT.DMA_Priority = DMA_Priority_High;
DMA_INIT.DMA_FIFOMode = DMA_FIFOMode_Disable; 
DMA_INIT.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_INIT.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_INIT.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream4, &DMA_INIT);
DMA_Cmd(DMA2_Stream4, ENABLE);
gpio_F.GPIO_Mode = GPIO_Mode_AN;
gpio_F.GPIO_Pin = GPIO_Pin_9;
gpio_F.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOF, &gpio_F);
ADC_COMMON.ADC_Mode = ADC_Mode_Independent;
ADC_COMMON.ADC_Prescaler = ADC_Prescaler_Div2;
ADC_COMMON.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_COMMON.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&ADC_COMMON);
ADC_INIT.ADC_Resolution = ADC_Resolution_12b;
ADC_INIT.ADC_ScanConvMode = DISABLE;
ADC_INIT.ADC_ContinuousConvMode = DISABLE; // ENABLE for max ADC sampling frequency
ADC_INIT.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_INIT.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_TRGO;
ADC_INIT.ADC_DataAlign = ADC_DataAlign_Right;
ADC_INIT.ADC_NbrOfConversion = 1;
ADC_Init(ADC3, &ADC_INIT);
ADC_RegularChannelConfig(ADC3, ADC_Channel_7, 1, ADC_SampleTime_3Cycles);
ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);
ADC_DMACmd(ADC3, ENABLE);
ADC_Cmd(ADC3, ENABLE);
}

#dma #adc

[stm322399]

Posted on June 30, 2014 at 10:51

If your board is fitted with STM32F407, the reference manual of this MCU says that ADC3 is available on Channel 2, Stream 0 or Stream 1 of DMA2.

[paul2]

Posted on June 30, 2014 at 11:22

Hi,

Thanks. Changes adapted, problem solved.