STM32F407 Continuous Conversion Issue Using ADC and DMA

[mikey880870]

I am currently using ADC for continuous conversion. Below is my program.

#include "adc.h"

void adc_init(ADC_TypeDef* adc){

// ADC3 PC0 PC1 (IN10 IN11)

RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN;

RCC->APB2ENR |= RCC_APB2ENR_ADC3EN;

// analog mode

GPIOC->MODER |= (3 << GPIO_MODER_MODE0_Pos);

GPIOC->MODER |= (3 << GPIO_MODER_MODE1_Pos);

// enable scan mode

adc->CR1 = (0x1 << ADC_CR1_SCAN_Pos);

// 12bit resolution

adc->CR1 |= (0x0 << ADC_CR1_RES_Pos);

//Continuous Conversion

adc->CR2 = (0x1 << ADC_CR2_CONT_Pos);

//EOC after each conversion

adc->CR2 |= (0x1 << ADC_CR2_EOCS_Pos);

// Data Alignment RIGHT

adc->CR2 &= ~(0x1 << ADC_CR2_ALIGN_Pos);

// Enable DMA for ADC

adc->CR2 |= (0x1 << ADC_CR2_DMA_Pos);

// Enable Continuous Request

adc->CR2 |= (0x1 << ADC_CR2_DDS_Pos);

// sampling time

adc->SMPR1 |= ((0x3 << ADC_SMPR1_SMP10_Pos) | (0x3 << ADC_SMPR1_SMP11_Pos));

adc->SMPR1 |= (0x3 << ADC_SMPR1_SMP10_Pos);

//Set the Regular channel sequence length in ADC_SQR1

adc->SQR1 |= (0x0 << ADC_SQR1_L_Pos);

// Channel Sequence

adc->SQR3 |= (10 << ADC_SQR3_SQ1_Pos);

adc->SQR3 |= (11 << ADC_SQR3_SQ2_Pos);

// enable adc

adc->CR2 |= (1 << ADC_CR2_ADON_Pos);

delay_ms(2000);

}

void adc_psc(ADC_Common_TypeDef* adc){

// ADC prescaler divide two

adc->CCR |= (0x0 << ADC_CCR_ADCPRE_Pos);

}

void start_adc(ADC_TypeDef* adc){

adc->SR = 0;

adc->CR2 |= (1 << ADC_CR2_SWSTART_Pos);

}

#include "dma.h"

void init_dma(DMA_TypeDef* dma){

//enable dma2

RCC->AHB1ENR |= RCC_AHB1ENR_DMA2EN;

// ADC3 -> DMA2 stream 0 channel 2

// Data direction

DMA2_Stream0->CR &= ~(3 << DMA_SxCR_DIR_Pos);

// Select Circular mode

DMA2_Stream0->CR |= (1 << DMA_SxCR_CIRC_Pos);

// Enable Memory Address Increment

DMA2_Stream0->CR |= (1 << DMA_SxCR_MINC_Pos);

// Set the size for data 16 bit 

DMA2_Stream0->CR |= ((1 << DMA_SxCR_MSIZE_Pos) | (1 << DMA_SxCR_PSIZE_Pos));

// channel 2

DMA2_Stream0->CR |= (0x2 << DMA_SxCR_CHSEL_Pos);

}

void start_dma(uint32_t scrAddress,uint32_t destAddress){

//  Set the size of the transfer

DMA2_Stream0->NDTR = 0x2;

// Source address is peripheral address

DMA2_Stream0->PAR = scrAddress;

// memory address

DMA2_Stream0->M0AR = destAddress;

//start

DMA2_Stream0->CR |= (1 << DMA_SxCR_EN);

}

#include "adc.h"

#include "uart.h"

#include "delay.h"

#include "dma.h"

#include <stdio.h>

#define pc_mcu_uart USART2

uint16_t Rxdata[2] = {0};

int fputc(int ch, FILE* stream){

USART_sendByte(USART2,ch);

return ch;

}

int main(void){

init_dma(adc_dma);

adc_psc(ADC123_COMMON);

adc_init(hw504_adc);

init_uart(pc_mcu_uart);

start_adc(hw504_adc);

start_dma((uint32_t)&ADC3->DR,(uint32_t)Rxdata);

delay_ms(100);

while(1){

printf("%d",ADC3->DR);

printf("x = %d\n",Rxdata[0]);

printf("y = %d\n",Rxdata[1]);

delay_ms(200);

}

return 0;

}
My ADC conversion is only successful after the first reset, and the Rxdata values are all zero.

Does any expert know where the problem is in my program?

[TDK]

Rxdata should be defined as volatile.

> //Set the Regular channel sequence length in ADC_SQR1

> adc->SQR1 |= (0x0 << ADC_SQR1_L_Pos);

With 2 channels, shouldn't this be 1?

Might want to use CubeMX to code this and compare your register values to what it produces. Can also debug the program and examine registers to determine what is happening.

[mikey880870]

Yes, you're right, here it should be changed to 0X1, but the result remains the same as before.
I've tried comparing it with mx, but still don't know where the problem is.

[TDK]

Rxdata should be defined as volatile.

> I've tried comparing it with mx

Keep trying. Show a screenshot with your values and the values from CubeMX. If one works and the other doesn't, there's a difference somewhere.

[waclawek.jan]

Always start debugging peripherals by reading out and checking content of relevant registers - here, ADC and DMA.

If you'd do that, you would soon discover, that the DMA channel's CR does not have the enable bit set.

> //start
> DMA2_Stream0->CR |= (1 << DMA_SxCR_EN);

is incorrect, should be

//start
DMA2_Stream0->CR |= (1 << DMA_SxCR_EN_Pos);

As conversions were ongoing but DMA was not there to pick the data, ADC overrun and stopped (btw. for that reason you want to enable DMA before starting ADC).

JW