Simple digital voltmeter + ADC0809 + program query method to achieve 8-channel data conversion

1 Experimental phenomenon (the analog signal acquisition channel is automatically switched every 1s, and the measured voltage value is displayed through the digital tube)

2 Hardware Design

3 Programming

3.1 Main function

#include

#include "DisplaySmg.h"

#include "ADC0809.h"

#include "Timer0.h"

unsigned char adc_result = 0; //Data collected directly after ADC conversion

int adc_result_show = 0; // linear scale change

unsigned char adc_flag = 1; //1s flag signal, used to automatically switch channels

unsigned char channel = 0; //channel number 0~7

void disp_num(void) //Display four-digit decimal number

{

LedBuf[0]= channel; //channel number

LedBuf[1]= adc_result_show/100; //hundreds place

LedBuf[2]= adc_result_show/10%10; //ten digit

LedBuf[3]= adc_result_show%10; //unit digit

}

void main()

{

Timer0_Init(); //Timer/Counter T0 initialization

EA=1; //Interrupt main switch

DotDig1=1; //light up the decimal point of the second digital tube

while(1)

{

if(adc_flag==1) //1S time flag signal

{

adc_flag = 0; // clear to use Timer0 for timing

adc_result = ADC_Conv(channel); //Collect channel input data through ADC

adc_result_show = adc_result*1.0*100*5/255; //Data conversion processing (linear scale conversion)

disp_num(); //Display data

channel++; //Switch to the next channel

if(channel>7) channel = 0;

}

}

}

//1ms timing, dynamically refresh the digital tube, and refresh adc_flag=1 every 1000ms

void Timer0_ISR(void) interrupt 1

{

static unsigned int timer0cnt;

TR0=0; //Turn off the timer

timer0cnt++;

if(timer0cnt>=1000)

{

timer0cnt = 0;

adc_flag = 1;

}

DisplaySmg(); //Refresh the digital tube display function every 1ms

TL0 = 0x66; //Set the initial timing value, timing 1ms

TH0 = 0xFC; //Set the initial timing value, timing 1ms

TR0=1; //Turn on the timer

}

3.2 ADC0809 analog-to-digital conversion function

#ifndef __ADC0809_H__

#define __ADC0809_H__

#include

#define ADC_DATA P3

sbit ADDR_A = P1^0;

sbit ADDR_B = P1^1;

sbit ADDR_C = P1^2;

sbit START = P1^4;

sbit EOC = P1^5;

sbit OE = P1^6;

unsigned char ADC_Conv(unsigned char channel);

#endif

#include "ADC0809.h"

void ADC_SetChannel(channel)

{

switch(channel)

{

case 0: ADDR_A = 0; ADDR_B = 0; ADDR_C = 0; break;

case 1: ADDR_A = 1; ADDR_B = 0; ADDR_C = 0; break;

case 2: ADDR_A = 0; ADDR_B = 1; ADDR_C = 0; break;

case 3: ADDR_A = 1; ADDR_B = 1; ADDR_C = 0; break;

case 4: ADDR_A = 0; ADDR_B = 0; ADDR_C = 1; break;

case 5: ADDR_A = 1; ADDR_B = 0; ADDR_C = 1; break;

case 6: ADDR_A = 0; ADDR_B = 1; ADDR_C = 1; break;

case 7: ADDR_A = 1; ADDR_B = 1; ADDR_C = 1; break;

default: break;

}

}

unsigned char ADC_Conv(unsigned char channel)

{

unsigned char adc_result;

OE = 0; //Data output enable signal, high level is valid

START = 0; //ADC conversion start signal, high level is valid, connected with ALE (address latch enable signal) in the circuit

ADC_SetChannel(channel); //Select channel

START = 1; //Rising edge, clear the register inside the ADC

START = 0; //Generate a certain pulse, Typ = 100ns, the falling edge starts AD conversion

while(EOC==0); //Query mode, ADC conversion end signal, EOC=1, conversion end

// DelayXms(1); //Delay waiting mode

OE = 1; //Data update to output port

adc_result = ADC_DATA; //MCU reads data

OE = 0; //This process ends

return adc_result;

}

3.3 Digital tube dynamic display function

#ifndef __DisplaySmg_H__

#define __DisplaySmg_H__

#include

#define GPIO_SEG P0 //Segment select port

#define GPIO_SEL P2 //bit select port

extern unsigned char LedBuf[]; //external variable declaration

extern unsigned char DotDig0,DotDig1,DotDig2,DotDig3;

void DisplaySmg(void);

#endif

#include "DisplaySmg.h"

unsigned char code LedData[]={ //segment code table, character, serial number of common cathode digital tube

0x3F, //"0", 0

0x06, //"1", 1

0x5B, //"2", 2

0x4F, //"3", 3

0x66, //"4", 4

0x6D, //"5", 5

0x7D, //"6", 6

0x07, //"7", 7

0x7F, //"8", 8

0x6F, //"9", 9

0x77, //"A", 10

0x7C, //"B", 11

0x39, //"C", 12

0x5E, //"D", 13

0x79, //"E", 14

0x71, //"F", 15

0x76, //"H", 16

0x38, //"L", 17

0x37, //"n", 18

0x3E, //"u", 19

0x73, //"P", 20

0x5C, //"o", 21

0x40, //"-", 22

0x00, //turn off 23

};

unsigned char DotDig0=0,DotDig1=0,DotDig2=0,DotDig3=0; //decimal point control bit

unsigned char code LedAddr[]={0xfe,0xfd,0xfb,0xf7}; //digital tube position selection

unsigned char LedBuf[]={22,22,22,22}; //Display buffer area

void DisplaySmg() //Four-digit digital tube, consider the decimal point

{

unsigned char i; // equivalent to "static unsigned char i = 0;"

unsigned char temp;

switch(i)

{

case 0:

{

GPIO_SEG = 0x00; //Eliminate shadow

if(DotDig0==1) //decimal point

{

temp = LedData[LedBuf[0]] | 0x80; //Light up the decimal point

}

else

{

temp = LedData[LedBuf[0]];

}

GPIO_SEG = temp; //segment code

GPIO_SEL = LedAddr[0]; //bit selection

i++;

break;

}

case 1:

GPIO_SEG = 0x00;

if(DotDig1==1) //decimal point

{

temp = LedData[LedBuf[1]] | 0x80;

}

else

{

temp = LedData[LedBuf[1]];

}

GPIO_SEG = temp;

GPIO_SEL = LedAddr[1];

i++;

break;

case 2:

GPIO_SEG = 0x00;

if(DotDig2==1) //decimal point

{

temp = LedData[LedBuf[2]] | 0x80;

}

else

{

temp = LedData[LedBuf[2]];

}

GPIO_SEG = temp;

GPIO_SEL = LedAddr[2];

i++;

break;

case 3:

GPIO_SEG = 0x00;

if(DotDig3==1) //decimal point

{

temp = LedData[LedBuf[3]] | 0x80;

}

else

{

temp = LedData[LedBuf[3]];

}

GPIO_SEG = temp;

GPIO_SEL = LedAddr[3];

i=0;

break;

default:break;

}

}

3.4 Timer T0

#ifndef __Timer0_H__

#define __Timer0_H__

#include

void Timer0_Init(void);

#endif

#include "Timer0.h"

void Timer0_Init(void) //1 millisecond @ 11.0592MHz

{

TMOD &= 0xF0; //Set timer mode

TMOD |= 0x01; //Set timer mode

TL0 = 0x66; //Set the initial value of the timing

TH0 = 0xFC; //Set the initial value of the timing

TF0 = 0; // Clear TF0 flag

TR0 = 1; //Timer 0 starts timing

ET0 = 1; //Timer 0 interrupt switch

//EA = 1; //Interrupt main switch

}

4 References

(1) Single chip microcomputer application - ADC0809 query method to realize AD conversion of 8 analog signals_bilibili_bilibili;