STM32 ADC gets battery voltage

adc.c

#include "adc.h"

void  Adc_Init(void)

{    

  ADC_InitTypeDef ADC_InitStructure; 

GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA |RCC_APB2Periph_ADC1, ENABLE); //Enable ADC1 channel clock

RCC_ADCCLKConfig(RCC_PCLK2_Div6); //Set ADC division factor 6 72M/6=12, ADC maximum time cannot exceed 14M

//PA4 is used as analog channel input pin                         

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN; //Analog input pin

GPIO_Init(GPIOA, &GPIO_InitStructure);

ADC_DeInit(ADC1); //Reset ADC1 and reset all registers of peripheral ADC1 to default values

ADC_InitStructure.ADC_Mode = ADC_Mode_Independent; //ADC working mode: ADC1 and ADC2 work in independent mode

ADC_InitStructure.ADC_ScanConvMode = DISABLE; //Analog-to-digital conversion works in single-channel mode

ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; //Analog-to-digital conversion works in single conversion mode

ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None; //Conversion is started by software instead of external trigger

ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; //ADC data right aligned

ADC_InitStructure.ADC_NbrOfChannel = 1; //Number of ADC channels for sequential regular conversion

ADC_Init(ADC1, &ADC_InitStructure); //Initialize the registers of the peripheral ADCx according to the parameters specified in ADC_InitStruct   

ADC_Cmd(ADC1, ENABLE); //Enable the specified ADC1

ADC_ResetCalibration(ADC1); //Enable reset calibration   

while(ADC_GetResetCalibrationStatus(ADC1)); //Wait for reset calibration to end

ADC_StartCalibration(ADC1); //Start AD calibration

while(ADC_GetCalibrationStatus(ADC1)); //Wait for calibration to end

}

u16 Get_Adc(u8 ch)   

{

  //Set the specified ADC rule group channel, a sequence, sampling time

ADC_RegularChannelConfig(ADC1, ch, 1, ADC_SampleTime_239Cycles5 ); //ADC1, ADC channel, sampling time is 239.5 cycles        

ADC_SoftwareStartConvCmd(ADC1, ENABLE); //Enable the software conversion start function of the specified ADC1  

while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC )); //Wait for the conversion to end

return ADC_GetConversionValue(ADC1); //Return the most recent conversion result of the ADC1 rule group

}

int Get_battery_volt(void)   

{  

int Volt; //Battery voltage

Volt=Get_Adc(Battery_Ch)*3.3*11.5*100/1.5/4096; //Resistor voltage division, according to the schematic diagram, a simple analysis can be obtained

if(Volt>1260)Volt=1260;

return Volt;

}

adc.h

#ifndef _ADC_H

#define _ADC_H

#include "config.h"

#define Battery_Ch 4

void Adc_Init(void);

u16 Get_Adc(u8 ch);

int Get_battery_volt(void); 

#endif