一 STC32G单片机内置ADC模块简介
STC32G单片机内部集成了一个12位高速ADC转换器，ADC的最高时钟频率为系统频率的1/2。其输入通道多达15个（第15通道为专门测量内部1.19V参考信号源的通道），可分时切换使用。
注意：STC32GADC模块的参考电压输入引脚不可悬空。
STC32G单片机的内置ADC模块转换结果存储在两个8位寄存器中，可配置为左对齐（高8位存储在高位寄存器ADC_RES中，低四位存储在低位寄存器ADC_REL的高四位中），可配置为右对齐（高4位存储在高位寄存器ADC_RES的低4位中，低8位存储在低位寄存器ADC_REL中）。
二 STC32G单片机内置ADC模块的相关寄存器
STC32G单片机内置ADC模块的相关寄存器包含控制寄存器ADC_CONTR、转换结果高位寄存器ADC_RES、转换结果低位寄存器ADC_RESL、配置寄存器ADCCFG、时序控制寄存器ADCTIM。下面是STC用户手册对这几个寄存器的功能介绍。
寄存器ADC_CONTR
配置寄存器ADCCFG
时序控制寄存器ADCTIM
三 ADC模块函数库编程
ADC模块应用离不开相关寄存器编程，先将常用的寄存器配置操作编写成库函数供以后调用。
头文件
/*STC32G_ADC.h
Designed by Bill Liu
Version 0.0
Modified last by Bill Liu,7/21/2022
/enum//
STC32G_ADC_CHN //STC32G ADC channel
STC32G_ADC_SPEED //STC32G ADC clock frequency
/Macro function
STC32G_ADCPOWERON(); //adc power on
STC32G_ADCPOWEROFF(); //adc power off
STC32G_ADCSTART(); //adc start
STC32G_ADCSTOP(); //adc stop
STC32G_ADCCLEARFLAG(): //clear flag
STC32G_ADCPWMTRIENBLE(); //PWM trigger adc enable
STC32G_ADCPWMTRIDISBLE(); //PWM trigger adc disable
STC32G_ADCSELCH0(); //selected ADC_CH0
STC32G_ADCSELCH1(); //selected ADC_CH1
STC32G_ADCSELCH2(); //selected ADC_CH2
STC32G_ADCSELCH3(); //selected ADC_CH3
STC32G_ADCSELCH4(); //selected ADC_CH4
STC32G_ADCSELCH5(); //selected ADC_CH5
STC32G_ADCSELCH6(); //selected ADC_CH6
STC32G_ADCSELCH7(); //selected ADC_CH7
STC32G_ADCSELCH8(); //selected ADC_CH8
STC32G_ADCSELCH9(); //selected ADC_CH9
STC32G_ADCSELCH10(); //selected ADC_CH10
STC32G_ADCSELCH11(); //selected ADC_CH11
STC32G_ADCSELCH12(); //selected ADC_CH12
STC32G_ADCSELCH13(); //selected ADC_CH13
STC32G_ADCSELCH14(); //selected ADC_CH14
STC32G_ADCSELCH15(); //selected ADC_CH15 at inner band gap voltage
STC32G_ADCRESLALIG(); //adc result left alignment
STC32G_ADCRESRALIG(): //adc result right alignment
//fuanction/
STC32G_AdcSelChn(STC32G_ADC_CHN chn); //return void
STC32G_AdcSelSpeed(STC32G_ADC_SPEED selSpeed); //return void
STC32G_AdcStructInitDef(STC32G_ADC_TypeDef* pStruct); //return void
STC32G_AdcInit(STC32G_ADC_TypeDef mStruct); //return void
STC32G_AdcGetRes(ui16* pResult); //return ui16
*/
#ifndef __STC32G_ADC_H
#define __STC32G_ADC_H
#include "config.h"
#include "STC32G_GPIO.h"
#define STC32G_ADCPOWERON() {ADC_POWER = 1;} //adc power on
#define STC32G_ADCPOWEROFF() {ADC_POWER = 0;} //adc power off
#define STC32G_ADCSTART() {ADC_START = 1;} //adc start
#define STC32G_ADCSTOP() {ADC_START = 0;} //adc stop
#define STC32G_ADCCLEARFLAG() {ADC_FLAG = 0;} //clear flag
#define STC32G_ADCPWMTRIENBLe() {ADC_EPWMT = 1;} //PWM trigger adc enable
#define STC32G_ADCPWMTRIDISBLE() {ADC_EPWMT = 0;} //PWM trigger adc disable
#define STC32G_ADCSELCH0() {STC32G_P1MODE_HIIN(PIN0); ADC_CONTR &= 0xF0;} //selected ADC_CH0
#define STC32G_ADCSELCH1() {STC32G_P1MODE_HIIN(PIN1); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x01;} //selected ADC_CH1
#define STC32G_ADCSELCH2() {STC32G_P1MODE_HIIN(PIN2); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x02;} //selected ADC_CH2
#define STC32G_ADCSELCH3() {STC32G_P1MODE_HIIN(PIN3); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x03;} //selected ADC_CH3
#define STC32G_ADCSELCH4() {STC32G_P1MODE_HIIN(PIN4); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x04;} //selected ADC_CH4
#define STC32G_ADCSELCH5() {STC32G_P1MODE_HIIN(PIN5); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x05;} //selected ADC_CH5
#define STC32G_ADCSELCH6() {STC32G_P1MODE_HIIN(PIN6); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x06;} //selected ADC_CH6
#define STC32G_ADCSELCH7() {STC32G_P1MODE_HIIN(PIN7); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x07;} //selected ADC_CH7
#define STC32G_ADCSELCH8() {STC32G_P0MODE_HIIN(PIN0); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x08;} //selected ADC_CH8
#define STC32G_ADCSELCH9() {STC32G_P0MODE_HIIN(PIN1); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x09;} //selected ADC_CH9
#define STC32G_ADCSELCH10() {STC32G_P0MODE_HIIN(PIN2); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x10;} //selected ADC_CH10
#define STC32G_ADCSELCH11() {STC32G_P0MODE_HIIN(PIN3); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x11;} //selected ADC_CH11
#define STC32G_ADCSELCH12() {STC32G_P0MODE_HIIN(PIN4); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x12;} //selected ADC_CH12
#define STC32G_ADCSELCH13() {STC32G_P0MODE_HIIN(PIN5); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x13;} //selected ADC_CH13
#define STC32G_ADCSELCH14() {STC32G_P0MODE_HIIN(PIN6); ADC_CONTR &= 0xF0; ADC_CONTR |= 0x14;} //selected ADC_CH14
#define STC32G_ADCSELCH15() { ADC_CONTR &= 0xF0; ADC_CONTR |= 0x15;} //selected band gap voltage
#define STC32G_ADCRESLALIG() {RESFMT = 0;} //adc result left alignment
#define STC32G_ADCRESRALIG() {RESFMT = 1;} //adc result right alignment
//******************************************************
typedef enum
{
ADC_CH0 = 0, //ADC channel 0 at P10
ADC_CH1, //ADC channel 1 at P11
ADC_CH2, //ADC channel 2 at P54
ADC_CH3, //ADC channel 3 at P13
ADC_CH4, //ADC channel 4 at P14
ADC_CH5, //ADC channel 5 at P15
ADC_CH6, //ADC channel 6 at P16
ADC_CH7, //ADC channel 7 at P17
ADC_CH8, //ADC channel 8 at P00
ADC_CH9, //ADC channel 9 at P01
ADC_CH10, //ADC channel 10 at P02
ADC_CH11, //ADC channel 11 at P03
ADC_CH12, //ADC channel 12 at P04
ADC_CH13, //ADC channel 13 at P05
ADC_CH14, //ADC channel 14 at P06
ADC_CH15, //ADC channel 15 at inner band gap voltage
}STC32G_ADC_CHN; //STC32G ADC channel
//******************************************************
typedef enum
{
FOSC_DIV_2X1 = 0, // FOSC / (2 * 1)
FOSC_DIV_2X2, // FOSC / (2 * 2)
FOSC_DIV_2X3, // FOSC / (2 * 3)
FOSC_DIV_2X4, // FOSC / (2 * 4)
FOSC_DIV_2X5, // FOSC / (2 * 5)
FOSC_DIV_2X6, // FOSC / (2 * 6)
FOSC_DIV_2X7, // FOSC / (2 * 7)
FOSC_DIV_2X8, // FOSC / (2 * 8)
FOSC_DIV_2X9, // FOSC / (2 * 9)
FOSC_DIV_2X10, // FOSC / (2 * 10)
FOSC_DIV_2X11, // FOSC / (2 * 11)
FOSC_DIV_2X12, // FOSC / (2 * 12)
FOSC_DIV_2X13, // FOSC / (2 * 13)
FOSC_DIV_2X14, // FOSC / (2 * 14)
FOSC_DIV_2X15, // FOSC / (2 * 15)
FOSC_DIV_2X16, // FOSC / (2 * 16)
}STC32G_ADC_SPEED; //STC32G ADC clock frequency
//******************************************************
typedef struct
{
BOOL adcPowerOn; //ADC power on enable/disable, 0-disable, 1-enable
STC32G_ADC_CHN adcChn; //slected adc channel
BOOL pwmTrigAble;
STC32G_ADC_SPEED adcSpeed; //STC32G_ADC_SPEED
BOOL adcResultRA; //adc result_data style,0:left alignment(default), 1:right alignment
BOOL adcSetupTime; //ADC channel select setup time control congigure, 0: 1 system clock cycles(default), 1: 2 system clock cycles
u8 adcHoldTime; //ADC channel select hold time control congigure. 0: 1 ADC clock cycle time, 1:2 ADC clock cycle times
u8 adcSampleTime; //analog signal sampling control time. 10 min. recommended 0x1F
}STC32G_ADC_TypeDef;
/******************************************************
Function: STC32G_AdcSelChn(STC32G_ADC_CHN chn);
return value: void
chn:adc channel
description: select adc channel
Example:
STC32G_AdcSelChn(ADC_CH0);
******************************************************/
void STC32G_AdcSelChn(STC32G_ADC_CHN chn);
/******************************************************
Function: STC32G_AdcSelSpeed(STC32G_ADC_SPEED selSpeed);
return value: void
selSpeed:selected speed
description: configure adc speed
Example:
STC32G_AdcSelSpeed(FOSC_DIV_2X16);
******************************************************/
void STC32G_AdcSelSpeed(STC32G_ADC_SPEED selSpeed);
/******************************************************
Function: STC32G_AdcInitDef(STC32G_ADC_TypeDef* pStruct);
return value: void
pStruct: STC32G_ADC_TypeDef struct address to be inited to default
description: Init STC32G_ADC_TypeDef struct to default value
Example:
STC32G_ADC_TypeDef mStruct;
STC32G_AdcInitDef(&mStruct);
******************************************************/
void STC32G_AdcInitDef(STC32G_ADC_TypeDef* pStruct);
/******************************************************
Function: STC32G_AdcInit(STC32G_ADC_TypeDef mStruct);
return value: void
mStruct: configure STC32G by mStruct
description: init adc
Example:
STC32G_ADC_TypeDef mStruct;
STC32G_AdcInit(mStruct);
******************************************************/
void STC32G_AdcInit(STC32G_ADC_TypeDef mStruct);
/******************************************************
Function: STC32G_AdcGetRes(ui16* pResult);
return value: ui16
pResult: address to store got result
description: get adc result
Example:
ui16 mReult;
STC32G_AdcGetRes(&mReult);
******************************************************/
u16 STC32G_AdcGetRes(ui16* pResult);
#endif源文件
/*STC32G_ADC.c
Designed by Bill Liu
Version 0.0
Modified last by Bill Liu, 07/21/2022
*/
#include "STC32G_ADC.h"
//******************************************************
void STC32G_AdcSelChn(STC32G_ADC_CHN chn)
{
switch(chn)
{
case ADC_CH0:
STC32G_ADCSELCH0()
break;
case ADC_CH1:
STC32G_ADCSELCH1()
break;
case ADC_CH2:
STC32G_ADCSELCH2()
break;
case ADC_CH3:
STC32G_ADCSELCH3()
break;
case ADC_CH4:
STC32G_ADCSELCH4()
break;
case ADC_CH5:
STC32G_ADCSELCH5()
break;
case ADC_CH6:
STC32G_ADCSELCH6()
break;
case ADC_CH7:
STC32G_ADCSELCH7()
break;
case ADC_CH8:
STC32G_ADCSELCH8()
break;
case ADC_CH9:
STC32G_ADCSELCH9()
break;
case ADC_CH10:
STC32G_ADCSELCH10()
break;
case ADC_CH11:
STC32G_ADCSELCH11()
break;
case ADC_CH12:
STC32G_ADCSELCH12()
break;
case ADC_CH13:
STC32G_ADCSELCH13()
break;
case ADC_CH14:
STC32G_ADCSELCH14()
break;
case ADC_CH15:
STC32G_ADCSELCH15()
break;
}
}
//End of STC32G_AdcSelChn(STC32G_ADC_CHN chn)
//******************************************************
void STC32G_AdcSelSpeed(STC32G_ADC_SPEED selSpeed)
{
ADCCFG &= 0xF0;
ADCCFG |= selSpeed;
}
//End of STC32G_AdcSelSpeed(STC32G_ADC_SPEED selSpeed)
//******************************************************
void STC32G_AdcInitDef(STC32G_ADC_TypeDef* pStruct)
{
pStruct -> adcPowerOn = 0;
pStruct -> adcChn = ADC_CH0;
pStruct -> pwmTrigAble = 0; //PWM trigger disable
pStruct -> adcSpeed = FOSC_DIV_2X1; //adc clk is sclok/2
pStruct -> adcResultRA = 0; //adc result left align
pStruct -> adcSetupTime = 0; //Tadcsetup a adc clk
pStruct -> adcHoldTime = 0x01; //adc hold time 2 adc clk
pStruct -> adcSampleTime = 0x0A; //adc sampling time: 11 adc clk, 0x0A <= adcSampleTime <= 0x1F
}
//End of STC32G_AdcInitDef(STC32G_ADC_TypeDef* pStruct)
//******************************************************
void STC32G_AdcInit(STC32G_ADC_TypeDef mStruct)
{
STC32G_AdcSelChn(mStruct.adcChn);
ADC_EPWMT = mStruct.pwmTrigAble;
ADCCFG &= 0xF0;
ADCCFG |= mStruct.adcSpeed;
RESFMT = mStruct.adcResultRA;
ADCTIM &= 0x7F;
ADCTIM |= mStruct.adcSetupTime;
ADCTIM &= 0x9F;
ADCTIM |= mStruct. adcHoldTime;
ADCTIM &= 0xE0;
ADCTIM |= mStruct. adcSampleTime;
ADC_POWER = mStruct.adcPowerOn;
}
//End of STC32G_AdcInit(STC32G_ADC_TypeDef mStruct)
//******************************************************
u16 STC32G_AdcGetRes(ui16* pResult)
{
*pResult = 0;
STC32G_ADCSTART();
_nop_();
_nop_();
while(!ADC_FLAG);
STC32G_ADCCLEARFLAG()
*pResult = ADC_RES;
if(RESFMT)
{
*pResult <<= 8;
*pResult += ADC_RESL;
}
else
{
*pResult <<= 4;
*pResult += ADC_RESL >> 4;
}
return *pResult;
}
//End of STC32G_AdcGetRes(ui16* pResult)四 应用编程示例
下面写段示例程序，演示ADC库文件的使用。
头文件：
/*main.h
Designed by Bill Liu
Version 0.0
Modified last by Bill Liu ,04/18/2023
*/
#ifndef __MAIN_H__
#define __MAIN_H__
//#include "myport.h"
#include "mtype.h"
#include "config.h"
#include "STC32G_GPIO.h"
#include "STC32G_Delay.h"
#include "STC32G_UART.h"
//#include "STC32G_EEPROM.h"
//#include "STC32G_PWM.h"
#include "STC32G_ADC.h"
//#include "STC32G_EEPROM.H"
//#include "STC32G_SPI.h"
//#include "STC32G_PWM.h"
//#include "STC32G_Timer.h"
//#include "STC32G_comparator.h"
STC32G_ADC_TypeDef mstruct;
#endif源文件：
/*main.c
Designed by Bill Liu
Version 0.0
Modified last by Bill Liu, 03/25/2023
*/
#include "main.h"
ui8 str[30] = {0};
ui16 ADCRes = 0;
f32 TestVoltage = 0;
void main()
{
SysInit();
Uart1_Init(VBAUD_8BITS,G1, 0, 9600);
STC32G_AdcInitDef(&mstruct);
mstruct.adcPowerOn = 1;
mstruct.adcChn = ADC_CH0;
mstruct.pwmTrigAble = 0;
mstruct.adcSpeed = FOSC_DIV_2X16;
mstruct.adcHoldTime = 0x01;
mstruct.adcSampleTime = 0x1F;
STC32G_AdcInit(mstruct);
while(1)
{
STC32G_AdcGetRes(&ADCRes);
Uart1_SendString("ADCRes = ");
LongToString(ADCRes,str);
Uart1_SendString(str);
Uart1_SendString("\r\n");
TestVoltage = 5000.0/4096*ADCRes;
FloatString(TestVoltage,str,2);
Uart1_SendString("TestVoltage = ");
Uart1_SendString(str);
Uart1_SendString("mV");
Uart1_SendString("\r\n");
/*
STC32G_ADCSELCH15()
STC32G_AdcGetRes(&ADCRes);
Uart1_SendString("ADCRes = ");
LongToString(ADCRes,str);
Uart1_SendString(str);
Uart1_SendString("\r\n");
TestVoltage = 5000.0/4096*ADCRes;
FloatString(TestVoltage,str,2);
Uart1_SendString("Inner Bandgap Voltage = ");
Uart1_SendString(str);
Uart1_SendString("mV");
Uart1_SendString("\r\n");
STC32G_ADCSELCH0()
*/
Uart1_SendString("This a ADC Test Program!");
Uart1_SendString("\r\n");
Uart1_SendString("\r\n");
Uart1_SendString("\r\n");
Delayxms(1000);
}
}
//End of main()测试板的参考电压为基准电压芯片AD586提供的5V电压。下面用一个10K的电位器将5V电源电压分压，将分压接到P1.0做AD输入，用ADC来测试分得电压的大小。
测得基准电压值：
测得分压值：
将程序编译，下载到单片机，在串口助手上看到的结果如下：
将源文件中的注释去掉，再获取内部Bandgap的ADC值，并将其转换为电压，结果如下：
从结果可以看出，获得的Bandgap电压并不是手册上所说的1.19V，至于为什么，不是此处讨论的范围。本例已完整演示了，如何调用ADC库函数，实现ADC值获取及如何用ADC测量电压。
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