Posted on June 11, 2013 at 02:12
Running the following two ADC3 inputs, channels 11 and 12 (PC1, light sensor and PC2 potentiometer) on STM32F4Discovery, problem is that when I vary the PC2 input, the reading pertaining to PC1 also varyies a bit. ??????
/* using ADC3, channel 11 and 12 for inputs to PC1 and PC2, in independent,
* scan mode with DMA
*/
#include ''stm32f4xx.h'' //includes stdint.h
#include <
stm32f4xx_usart.h
>
#include ''myUSART1.h''
#include <
misc.h
>
#include ''stm32f4xx_adc.h''
char buffer[4];
__IO uint16_t ConvertedValue[2];
#define ADC3_DR_ADDRESS ((uint32_t)0x4001224C) //Ref p. 54; Ref p. 307;
void ADC3_DMA_Config(void);
void my_itoa(int n, char A[]);
void reverse(char A[]);
int main(void){
ADC3_DMA_Config();
init_USART1(19200);
USART_puts(USART1, ''Ready for ADC Conversion'');
USART_puts(USART1, ''\n'');
ADC_SoftwareStartConv(ADC3);
while (1) {
ADC_SoftwareStartConv(ADC3);
my_itoa(ConvertedValue[0], buffer);
USART_puts(USART1, buffer);
USART_puts(USART1, ''\t'');
my_itoa(ConvertedValue[1], buffer);
USART_puts(USART1, buffer);
USART_puts(USART1, ''\n'');
}
return 1;
}
void ADC3_DMA_Config(void){
ADC_InitTypeDef myADC;
ADC_CommonInitTypeDef myComm;
DMA_InitTypeDef myDMA;
GPIO_InitTypeDef myGPIO;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2 | RCC_AHB1Periph_GPIOC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC3, ENABLE);
/* DMA2 Stream0 channel 2 configuration **************************************/
myDMA.DMA_Channel = DMA_Channel_2;
myDMA.DMA_PeripheralBaseAddr = (uint32_t)ADC3_DR_ADDRESS;
myDMA.DMA_Memory0BaseAddr = (uint32_t)&ConvertedValue;
myDMA.DMA_DIR = DMA_DIR_PeripheralToMemory;
myDMA.DMA_BufferSize = 2;
myDMA.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
myDMA.DMA_MemoryInc = DMA_MemoryInc_Enable;
myDMA.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; // u32
myDMA.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
myDMA.DMA_Mode = DMA_Mode_Circular;
myDMA.DMA_Priority = DMA_Priority_High;
myDMA.DMA_FIFOMode = DMA_FIFOMode_Disable;
myDMA.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
myDMA.DMA_MemoryBurst = DMA_MemoryBurst_Single;
myDMA.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream0, &myDMA);
DMA_Cmd(DMA2_Stream0, ENABLE);
/* Configure ADC3 Channel 11 and 12 pin as analog input ******************************/
myGPIO.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2;
myGPIO.GPIO_Mode = GPIO_Mode_AN;
myGPIO.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOC, &myGPIO);
/* ADC Common Init **********************************************************/
myComm.ADC_Mode = ADC_Mode_Independent;
myComm.ADC_Prescaler = ADC_Prescaler_Div2;
myComm.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled; //we not using multi mode
myComm.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles;
ADC_CommonInit(&myComm);
/* ADC3 Init ****************************************************************/
myADC.ADC_Resolution = ADC_Resolution_12b;
myADC.ADC_ScanConvMode = ENABLE; //more than one input
myADC.ADC_ContinuousConvMode = ENABLE;
myADC.ADC_ExternalTrigConv=ADC_ExternalTrigConv_T1_CC1;//=0
myADC.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
myADC.ADC_DataAlign = ADC_DataAlign_Right;
myADC.ADC_NbrOfConversion = 2;
ADC_Init(ADC3, &myADC);
/* ADC3 regular channel12 configuration *************************************/
ADC_RegularChannelConfig(ADC3, ADC_Channel_11, 1, ADC_SampleTime_3Cycles);
ADC_RegularChannelConfig(ADC3, ADC_Channel_12, 2, ADC_SampleTime_15Cycles);
/* Enable DMA request after last transfer (Single-ADC mode) */
ADC_DMARequestAfterLastTransferCmd(ADC3, ENABLE);
/* Enable ADC3 DMA */
ADC_DMACmd(ADC3, ENABLE);
/* Enable ADC3 */
ADC_Cmd(ADC3, ENABLE);
}
void my_itoa(int n, char A[])
{
int i =0;
do {
A[i++] = n % 10 + '0';
} while ((n /= 10) > 0); //we divide by ..continue as long as we can divide by 10 with
//integer left over, so stops with one digit
A[i] = '\0'; //this will become last digit once reverse is called
reverse(A);
}
void reverse(char A[])
{
int i, j;
char c;
for (i = 0, j = strlen(A)-1; i<j; i++, j--) {
c = A[i];
A[i] = A[j];
A[j] = c;
}
}
