分享一个用单片机比较器做电压表的程序 -

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本示例在Keil开发环境下请选择STC15系列芯片型号进行编译
本例程MCU的工作频率为24MHz, 工作电压3~5V均可.
使用MCU自带的比较器进行ADC转换, 并通过串口输出结果.
比较器配置为P5.5做高阻正输入, 接输入分压电阻, 比较器的负输入接到内部1.25V参考电压. P5.4配置为开漏输出, 做反馈来平衡电荷.
本例程使用680K+10K分压电阻接P5.5输出, 用定时器0产生20us中断查询比较器的状态, 从P3.6输出反馈来做电荷平衡.
最高输入电压 = 1.25 * (1 + 680 / 10) = 85 V. 程序显示1.25~84V, 低于1.25V返回000, 高于84V返回FFF.
例: 比较一次的时间间隔为10us, 量程为33200, 则做1次ADC的时间为33ms. 比较器的响应时间越短, 则完成ADC就越快.
由于要求每次比较时间间隔都要相等,所以用C编程最好在定时器中断里进行, 定时器设置为自动重装, 高优先级中断, 其它中断均低优先级.
用汇编的话, 保证比较输出电平处理的时间要相等.
680K
/| P5.5 ___
/+|-----------o-|___|- ------- Vin
----< | P5.4 ___ |
\-|-----|___|-o
\| 10K |
|
---
--- 104
|
|
===
GND
******************************/
#include "MAIN.H"
#include "EEPROM.C"
/************* 本地常量声明 **************/
#define BandGap 122 //1246 mv
#define ADC_SCALE *((unsigned short volatile data *)0x18)
#define ADC_Reference *((unsigned long volatile data *)0x18)
#define ADC_Multiple *((unsigned short volatile data *)0x1C)
#define BGP *((unsigned short volatile data *)0x1E)
//#define adc_value *((unsigned short volatile data *)0x38)
#define Value_H *((unsigned char volatile data *)0x20)
#define Value_L *((unsigned char volatile data *)0x21)
//u8 volatile data adc_temp[2] _at_ 0x30;
//#define BandGap *((unsigned short volatile data *)0x30)
//#define ADC_Multiple *((unsigned short volatile data *)0x32)
//#define ADC_SCALE *((unsigned short volatile data *)0x34)
//#define ADC_Reference *((unsigned long volatile data *)0x34)
u8 volatile data adc_temp[8] _at_ 0x18;
u16 volatile data adc_value _at_ 0x20;
//u8 volatile data Value_H _at_ 0x38;
//u8 volatile data Value_L _at_ 0x39;
#define CMPRES (CMPCR1 & 0x01)
//u8 code Led_Lib[] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
u8 code Led_Count[] = {0xf7,0xfb,0xfd};
/************* 本地变量声明 **************/
sbit P_ADC = P5^4; //P3.6 比较器转IO输出端
sbit Press = P3^0; //P3.0 按键检测IO
u8 data BandGap_addr, adc_addr, Key, Long_Press, Disp_Count, T2_Count;
u8 data Led_Temp[4], Led_Buf[3], Key_Press[3];
u16 data adc; //ADC中间值, 用户层不可见
u16 data adc_duty; //ADC计数周期, 用户层不可见
//u16 data adc_value; //ADC值, 用户层使用
bit Show_Mode, Edit_Mode, adc_ok; //ADC结束标志, 为1则adc_value的值可用. 此标志给用户层查询,并且清0
/************* 本地函数声明 **************/
void Get_ADCSCALE()
{
adc_temp[0] = 0xff;
while(adc_temp[0] == 0xff)
{
adc_temp[0] = Read_EepromH(--adc_addr);
}
adc_temp[1] = Read_EepromL(adc_addr);
}
void Save_ADCSCALE()
{
if(++adc_addr == 0x00) Erase_Eeprom();
Write_EepromH(adc_addr, adc_temp[0]);
Write_EepromL(adc_addr, adc_temp[1]);
}
/*
void Get_ADCSCALE()
{
adc_temp[0] = 0xff;
BandGap_addr = 0x80;
while(adc_temp[0] == 0xff)
{
adc_temp[0] = Read_EepromH(--BandGap_addr);
}
adc_temp[1] = Read_EepromH(BandGap_addr | 0x80);
adc_temp[2] = Read_EepromL(BandGap_addr);
adc_temp[3] = Read_EepromL(BandGap_addr | 0x80);
}
void Save_ADCSCALE()
{
if(++BandGap_addr == 0x80)
{
BandGap_addr = 0x00;
Erase_Eeprom();
}
Write_EepromH(BandGap_addr, adc_temp[0]);
Write_EepromH((BandGap_addr | 0x80), adc_temp[1]);
Write_EepromL(BandGap_addr, adc_temp[2]);
Write_EepromL((BandGap_addr | 0x80), adc_temp[3]);
}
void Reference_ADC()
{
ADC_Reference = BandGap * ADC_Multiple * 2621;
}
*/
void main(void)
{
IAP_CONTR = ENABLE_IAP;
Get_ADCSCALE();
// Reference_ADC();
P1Mode = DDPP_PPPP; //P1.5~P1.0 设置为强推挽输出（Led段码a~f）
P3Mode = PPDD_OOOD; //P3.7~P3.6 设置为强推挽输出（Led段码g、dp） P3.3~P3.1 设置为开漏输出（Led位码0~2） P3.0 设置为准双向（按键检测）
P5Mode = DDHO_DDDD; //P5.5 设置为高阻输入（adc正极输入，电压检测） P5.4 设置为开漏输出（adc电荷平衡）
TH0 = Reload_for_Timer0 / 256; //重装值中断率50KHZ, 中断周期20us
TL0 = Reload_for_Timer0 % 256;
T2H = Reload_for_Timer2 / 256;
T2L = Reload_for_Timer2 % 256; //设置波特率重装值
// 7 6 5 4 3 2 1 0
// IAP_CONTR=B_1000_0001; // IAPEN SWBS SWRST CMD_FAL - WT2 WT1 WT0
// IAP_CMD = B_0000_0001; // - - - - - - MS1 MS0 // IAP_TRIG = 5a a5
CMPCR1 = B_1000_0000; // CMPEN CMPIF PIE NIE PIS NIS CMPOE CMPRES
CMPCR2 = B_0000_0000; // INVCMPO DISFLT LCDTY[5:0]
// SCON = B_0101_0000; // SM0/FE SM1 SM2 REN TB8 RB8 TI RI
TMOD = B_0000_0000; // GATE C/T M1 M0 GATE C/T M1 M0
TCON = B_0001_0000; // TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
AUXR = B_1001_0000; // T0x12 T1x12 UARTxM6 T2R T2_C/T T2x12 EXTRAM S1ST2
IE2 = B_0000_0100; // - ET4 ET3 ES4 ES3 ET2 ESPI ES2
IP = B_0000_0010; // PPCA PLVD PADC PS PT1 PX1 PT0 PX0
IE = B_1000_0010; // EA ELVD EADC ES ET1 EX1 ET0 EX0
while (1)
{
if(Show_Mode)
{
Led_Buf[0] = Led_Lib(adc_temp[0] >> 4);
Led_Buf[1] = Led_Lib(adc_temp[0] & 0x0f);
Led_Buf[2] = Led_Lib(adc_temp[1] >> 4);
}
else
{
if(adc_ok) //等待ADC结束
{
Led_Temp[1] = Hex2BCD(Value_H);
Led_Temp[0] = Led_Temp[1] >> 4;
Led_Temp[1] |= 0xf0;
Led_Temp[3] = Hex2BCD(Value_L);
Led_Temp[2] = Led_Temp[3] >> 4;
Led_Temp[3] &= 0x0f;
if(adc_value > 999)
{
if(adc_value > 8400)
{
Led_Buf[0] = 0x71;
Led_Buf[1] = 0x71;
Led_Buf[2] = 0x71;
}
else
{
Led_Buf[0] = Led_Lib(Led_Temp[0]);
Led_Buf[1] = Led_Lib(Led_Temp[1]);
Led_Buf[2] = Led_Lib(Led_Temp[2]);
}
}
else
{
if(adc_value > 125)
{
Led_Buf[0] = Led_Lib(Led_Temp[1]);
Led_Buf[1] = Led_Lib(Led_Temp[2]);
Led_Buf[2] = Led_Lib(Led_Temp[3]);
}
else
{
Led_Buf[0] = 0x3f;
Led_Buf[1] = 0x3f;
Led_Buf[2] = 0x3f;
}
}
if(Edit_Mode) Led_Buf[2] |= 0x80;
adc_ok = 0; //清除ADC已结束标志
}
}
if(Key != 0x00)
{
switch(Key)
{
case 0x01:
if(Edit_Mode) ADC_SCALE -= 16;
if(Show_Mode) ADC_Multiple -= 1;
break;
case 0x02:
if(Edit_Mode) ADC_SCALE += 16;
if(Show_Mode) ADC_Multiple += 1;
break;
case 0x11:
if(!Show_Mode)
{
if(Edit_Mode)
{
Save_ADCSCALE();
Edit_Mode = 0;
}
else Edit_Mode = 1;
}
break;
case 0x12:
if(!Edit_Mode) Show_Mode = ~Show_Mode;
break;
default:
break;
}
Key = 0x00;
}
}
}
//==================== Timer0 中断函数（电压检测） ===============
void Timer0_Routine() interrupt 1 using 1
{
if(CMPRES)
{
P_ADC = 0;
adc++; //如比较结果为1，则adc计数加1
}
else P_ADC = 1;
if(--adc_duty == 0) //ADC周期-1, 到0则ADC结束
{
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