STM32 ADC1, multichannel & single conversion ?

[OppaErich 25]

I'm trying to read the output of a 3-axis accelerometer. X,Y and Z output are connected to ADC1 channels 10 to 12 of a STM32F103RB.

 

How can I do three channel A2D in single conversion mode ? There are lots of examples using continuous mode but none for single conversion mode. Here's my naive approach that did not work.

------------Edit----------------------

int main(void){

uint16_t ADCBuffer[] = {0xAAAA, 0xAAAA, 0xAAAA, 0xAAAA};

 

This works only using DMA, I found some demo code but the first line sends the MCU into an exception trap. How come ? If I change this to uint32_t then no exception occurs but I don't get sane readings. ADCBuffer[0] gets a large number, [1] is set to 1 and [2] stays at AAAA. Hmmmpf

 

#include "stm32f10x_conf.h"
#include "ITDB02_display.h"


int main(void){

uint16_t ADCBuffer[] = {0xAAAA, 0xAAAA, 0xAAAA, 0xAAAA};

InitLCD(LANDSCAPE, ASPECT_16x9);
fontSize(FONT_LARGE);
clrScr();
setColor(200,200,200);

GPIO_InitTypeDef GPIO_InitStructure;

ADC_InitTypeDef ADC_InitStructure;

DMA_InitTypeDef DMA_InitStructure;

SystemInit();

RCC_ADCCLKConfig(RCC_PCLK2_Div6);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO | RCC_APB2Periph_ADC1, ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

DMA_InitStructure.DMA_BufferSize = 3;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)ADCBuffer;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_Init(DMA1_Channel1, &DMA_InitStructure);

DMA_Cmd(DMA1_Channel1, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);

ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;
ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_InitStructure.ADC_NbrOfChannel = 3;
ADC_InitStructure.ADC_ScanConvMode = ENABLE;
ADC_Init(ADC1, &ADC_InitStructure);

ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_1Cycles5);
ADC_RegularChannelConfig(ADC1, ADC_Channel_11, 2, ADC_SampleTime_1Cycles5);
ADC_RegularChannelConfig(ADC1, ADC_Channel_12, 1, ADC_SampleTime_1Cycles5);

ADC_Cmd(ADC1, ENABLE);
ADC_DMACmd(ADC1, ENABLE);

ADC_ResetCalibration(ADC1);
while(ADC_GetResetCalibrationStatus(ADC1));
ADC_StartCalibration(ADC1);
while(ADC_GetCalibrationStatus(ADC1));


while(1){
ADC_SoftwareStartConvCmd(ADC1, ENABLE);

printNumI(ADCBuffer[0], 0,5);
printNumI(ADCBuffer[1], 0,20);
printNumI(ADCBuffer[2], 0,35);

if(ADCBuffer[3] != 0xAAAA)
print("Sumthin went WRONG HERE !",10,80,0);
}
for(;;
}

Edited August 6, 2012 by Oppa

[bluehash 1,578]

Liter posted a link here on single conversion ADC on an STM32.

[OppaErich 25]

Thanks but that is single channel too. Update above. I want to attach main.c, how do I ?

[OppaErich 25]

HAH I'm getting somewhere. I've changed the line

uint16_t ADCBuffer[] = {0xAAAA, 0xAAAA, 0xAAAA, 0xAAAA}; 

to

uint16_t ADCBuffer[4];
ADCBuffer[3] = 0xAAAA; 

and I get sane readings. Strange though, why does the compiler build something that sends the CPU into a trap ?