How do you configure DMA1 with multiple ADC channels with different buffer sizes?

[lmullane]

Posted on September 07, 2017 at 17:55

Hi

I'm using a STM32F103ZE

I'm trying to configure DMA1 with ADC1 Channels 12 & 16.

The code below works i.e. when the DMA flags the DMA_Buffer contains 800 samples,

   400 for Channel_12 and

   400 for Channel_16

However I only need a 4 samples for Channel_16

Is there a way to configure the DMA1 to retrieve 400 samples on Channel_12 and 4 samples on Channel_16 ?

Thanks

Liam

#define BUFF_SIZE 800

uint32_t DMA_Buffer[BUFF_SIZE];

void ConfigConductivityADC (void)

{

ADC_InitTypeDef ADC_InitStructure;

RCC_ADCCLKConfig(RCC_PCLK2_Div6);

ADC_DeInit(ADC1);

// ADC1 configuration

ADC_InitStructure.ADC_Mode= ADC_Mode_RegSimult;

ADC_InitStructure.ADC_ScanConvMode= ENABLE;

ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T3_TRGO;

ADC_InitStructure.ADC_DataAlign= ADC_DataAlign_Right;

ADC_InitStructure.ADC_NbrOfChannel= 2;

ADC_Init(ADC1, &ADC_InitStructure);

ADC_TempSensorVrefintCmd(ENABLE);

ADC_DMACmd(ADC1, ENABLE);

ADC_RegularChannelConfig(ADC1, ADC_Channel_12, 1, ADC_SampleTime_239Cycles5);

ADC_RegularChannelConfig(ADC1, ADC_Channel_16, 2, ADC_SampleTime_239Cycles5);

ADC_ExternalTrigConvCmd(ADC1, ENABLE);

ADC_Cmd(ADC1, ENABLE);

ADC_ResetCalibration(ADC1);

while(ADC_GetResetCalibrationStatus(ADC1));

ADC_StartCalibration(ADC1);

while(ADC_GetCalibrationStatus(ADC1));

}

void ConfigConductivityDMA(void)

{

DMA_InitTypeDef DMA_InitStructure;

/* DMA1 channel1 configuration ----------------------------------------------*/

DMA_DeInit(DMA1_Channel1);

DMA_InitStructure.DMA_PeripheralBaseAddr=ADC1_DR_Address;

DMA_InitStructure.DMA_MemoryBaseAddr=(uint32_t)DMA_Buffer;

DMA_InitStructure.DMA_DIR=DMA_DIR_PeripheralSRC;

DMA_InitStructure.DMA_BufferSize=BUFF_SIZE;

DMA_InitStructure.DMA_PeripheralInc=DMA_PeripheralInc_Disable;

DMA_InitStructure.DMA_MemoryInc=DMA_MemoryInc_Enable;

DMA_InitStructure.DMA_PeripheralDataSize=DMA_PeripheralDataSize_Word;

DMA_InitStructure.DMA_MemoryDataSize=DMA_MemoryDataSize_Word;

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);

}

[Tesla DeLorean]

Posted on September 07, 2017 at 18:31

>>Is there a way to configure the DMA1 to retrieve 400 samples on Channel_12 and 4 samples on Channel_16 ?

No.

You can play games with the Rank and sampling multiple times, but the ratio/trigger isn't going to work for you here.

Injected?

Use the other ADC?

Burn the memory, cherry pick values of interest?

Use less memory, manage in HT/TC interrupts?

[lmullane]

Posted on September 08, 2017 at 11:53

I'm already using ADC2 for SD.

For now I'm going to just going to

Disable the DMA for Channel 12,

ReConfigure and take a reading on Channel 16 (takes ~0.4 ms)

ReConfigure DMA ADC1 for Channel 12

I only need to poll Channel 12 once every few seconds so this workaround will do for now.

Thanks for the Feedback

Turvey.Clive.002

I just needed to know that it was not possible.