lft lft - 1 year ago 308
C Question

ADC single conversion on STM32

I'm studying ADC programming on STM32 F103x and starting with the simplest case - single conversion.
The internal temperature sensor (connected to ADC1) value is measured and sending it to COM port by using USART. A target seems clear but when I try to download source code to flash, it doesn't send any data to COM port. USART function works well, I guess the problems come from ADC configuration part because I'm being hung in loop of waiting complete conversion:

while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET); //Wail for conversion complete

Here is my source code so far.

/* Includes ------------------------------------------------------------*/
#include "stm32f10x.h"
#include <stdio.h>

uint16_t AD_value;
const uint16_t V25 = 1750; //when V25=1.41V
const uint16_t Avg_Slope = 5; //when avg_slc
uint16_t TemperatureC;

//Define output device
USART_SendData(USART1, (uint8_t) ch);
while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET)
return ch;

void Usart1Init(void)
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;


/* COnfig PA9 for USART Tx as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

/* COnfig PA10 for USART Rx as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);

/* USARTx configured as follow:
- BaudRate = 9600 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
USART_InitStructure.USART_BaudRate = 9600;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;

/* USART configuration */
USART_Init(USART1, &USART_InitStructure);


int main(void)

ADC_InitTypeDef ADC_InitStructure;

RCC_ADCCLKConfig(RCC_PCLK2_Div6); //ADCCLK = PCLK22/6 = 72/6=12MHz
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE); //Enable ADC1 Clock

/* ADC1 configuration */
ADC_DeInit(ADC1); //Power-on default
ADC_InitStructure.ADC_Mode = ADC_Mode_Independent; //Independent conversion mode (single)
ADC_InitStructure.ADC_ScanConvMode = DISABLE; //Convert single channel only
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; //Convert 1 time
ADC_InitStructure.ADC_ExternalTrigConv = DISABLE; //No external triggering
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //Right 12-bit data alignment
ADC_InitStructure.ADC_NbrOfChannel = 1; //single channel conversion
ADC_Init(ADC1, &ADC_InitStructure);
ADC_TempSensorVrefintCmd(ENABLE); //wake up temperature sensor
ADC_Cmd(ADC1, ENABLE); //Enable ADC1
ADC_ResetCalibration(ADC1); //Enable ADC1 reset calibration register
while(ADC_GetResetCalibrationStatus(ADC1)); //check the end of ADC1 reset calibration register
ADC_StartCalibration(ADC1); //Start ADC1 calibration
while(ADC_GetCalibrationStatus(ADC1)); //Check the end of ADC1 calibration
ADC_RegularChannelConfig(ADC1, ADC_Channel_16, 1, ADC_SampleTime_1Cycles5); //Select 1.5 cycles conversion for channel 16
ADC_SoftwareStartConvCmd(ADC1, ENABLE); //Start ADC1 software conversion
while(ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET); //Wail for conversion complete
AD_value = ADC_GetConversionValue(ADC1); //Read ADC value
ADC_ClearFlag(ADC1, ADC_FLAG_EOC); //Clear EOC flag

printf("\r\n ADC value: %d \r\n", AD_value);
TemperatureC = (uint16_t)((V25-AD_value)/Avg_Slope+25);
printf("Temperature: %d%cC\r\n", TemperatureC, 176);
while (1)

Any ideas are appreciated!

lft lft
Answer Source

Problem solved! It's my fault to disable external trigger. Instead of using:

ADC_InitStructure.ADC_ExternalTrigConv = DISABLE;

It shoud be like this:

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;

What a silly!

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