stm32 adc with dma

Posted on July 09, 2013 at 12:54

The array should be volatile, the paste is a bit sloppy, main exits, doesn't call anything, and doesn't loop.

Please, if you're going to do this, post a complete example.

Posted on July 09, 2013 at 13:45

 sorry , for what i did....in the org. code the functions has been called in main ......(just to save time,wrote partial code)

i wanted to ask, have i done it in the correct way of initializing the array in DMA and reading it in main,am i getting the correct  values (acc. to code) of all 3 adc channel values in the array. ?

void ADC_DMA_Configuration() {

GPIO_InitTypeDef GPIO_InitStructure; //Variable used to setup the GPIO pins

DMA_InitTypeDef DMA_InitStructure; //Variable used to setup the DMA

ADC_InitTypeDef ADC_InitStructure; //Variable used to setup the ADC

//==Configure the systems clocks for the ADC and DMA==

//ADCCLK = PCLK2 / 2

RCC_ADCCLKConfig(RCC_PCLK2_Div2); //Defines the ADC clock divider. This clock is derived from the APB2 clock (PCLK2). The

//ADCs are clocked by the clock of the high speed domian (APB2) dibivied by 2/4/6/8. The

//frequency can never be bigger than 14MHz!!!!

//--Enable DMA1 clock--

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

//--Enable ADC1 and GPIOC--

RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1 | RCC_APB2Periph_GPIOC , ENABLE);

 

//==Configure ADC pins (PC.00 -> Channel 10, PC.01 -> Channel 11 & PC.02 -> Channel 12) as analog inputs==

GPIO_StructInit(&GPIO_InitStructure); // Reset init structure, if not it can cause issues...

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1| GPIO_Pin_2;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;

GPIO_Init(GPIOC, &GPIO_InitStructure);

//==Configure DMA1 - Channel1=

DMA_DeInit(DMA1_Channel1); //Set DMA registers to default values

DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_Address; //Address of peripheral the DMA must map to

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t) & ADCConvertedValue; //Variable to which ADC values will be stored

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize = 3; //Buffer size (3 because we using 3 channels)

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;

DMA_InitStructure.DMA_Priority = DMA_Priority_High;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA1_Channel1, &DMA_InitStructure); //Initialise the DMA

DMA_Cmd(DMA1_Channel1, ENABLE); //Enable the DMA1 - Channel1

//////////////////////////////////////////////////////////////////////      

////////////////////////////////////////////////////////////////////////////

//==Configure ADC1 - Channel 14 and Channel 15==

ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;

ADC_InitStructure.ADC_ScanConvMode = ENABLE;

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfChannel = 3; //We using 3 channels

ADC_Init(ADC1, &ADC_InitStructure); //Initialise ADC1

//Setup order in which the Channels are sampled....

ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_55Cycles5);

ADC_RegularChannelConfig(ADC1, ADC_Channel_11, 2, ADC_SampleTime_55Cycles5);

ADC_RegularChannelConfig(ADC1, ADC_Channel_12, 3, ADC_SampleTime_55Cycles5);

ADC_DMACmd(ADC1, ENABLE); //Enable ADC1 DMA

ADC_Cmd(ADC1, ENABLE); //Enable ADC1

//==Calibrate ADC1==

//Enable ADC1 reset calibration register

ADC_ResetCalibration(ADC1);

while (ADC_GetResetCalibrationStatus(ADC1)); //Check the end of ADC1 reset calibration register

//Start ADC1 calibaration

ADC_StartCalibration(ADC1);

while (ADC_GetCalibrationStatus(ADC1)); //Check the end of ADC1 calibration

}//end ADC_Configuration

 

void ADC_DMA_Test_Program() 

{

/* Start ADC1 Software Conversion */

ADC_SoftwareStartConvCmd(ADC1, ENABLE);

}

void

main(void) 

{

      

ADC_DMA_Configuration();

 

    

ADC_DMA_Test_Program();

while (1)

{a=

 ADCConvertedValue

[0

]

;b=

ADCConvertedValue

[1

]

;

c=

ADCConvertedValue

[2

]

;

}

}

i also want to know about sampling time in this ADC, because i am not getting enough samples . does DMA read cycles affecting the samples?