STC89C52 microcontroller timer

How to set the timer?

For example:

Timing 50 microseconds

First of all, 50000 ÷ 1.085 = 46,082.94930875576. Starting from 0 and adding 19,453 times will overflow.     This calculation will have errors, but the impact is relatively small and can be ignored.

TH0 = (65535 - 46082) / 256; // Place the quotient in the upper eight bits

TL0 = (65535 - 46082) % 256; // Put the remainder in the lower eight bits

Or 65535 - 46082 = 19453

In hexadecimal we get: 4BFD

Binary gets: 0100 1011 1111 1101 

Put the obtained hexadecimal numbers into TH0 and TL0 respectively;

TH0 = 0x4b;

TL0 = 0xfd; //Timing 50ms

timer

Timer 0 working mode 1 16-bit timing mode, digital tube dynamically displays 0-10 stopwatch.

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

//Common cathode digital tube segment selection table 0-9

uchar code tabel[]= {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,};

/*====================================

Function : delay(uint z)

Parameter : z delay millisecond setting, value range 0-65535

Return value : None

Description : 12T/Fosc11.0592M millisecond delay

====================================*/

void delay(uint z)

{

uint x,y;

for(x = z; x > 0; x--)

for(y = 114; y > 0; y--);

} 

/*====================================

Function : display(uchar i)

Parameter : i displays the numerical value, the value range is 0-255

Return value : None

Description : Three-digit common cathode digital tube dynamic display

====================================*/

void display(uchar i)

{

uchar bai, shi, ge;

bai = i / 100; //236 / 100 = 2

shi = i % 100 / 10; //236 % 100 / 10 = 3

ge = i % 10;//236 % 10 =6

//The first digital tube 

P0 = 0XFF;//Clear broken code

WE = 1;//Open bit selection latch

P0 = 0XFE; //1111 1110

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = tabel[bai];//

DU = 0; //Latch segment selection data

delay(5);

//The second digital tube

P0 = 0XFF;//Clear broken code

WE = 1;//Open bit selection latch

P0 = 0XFD; //1111 1101

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = tabel[shi];//

DU = 0; //Latch segment selection data

delay(5);

//The third digital tube

P0 = 0XFF;//Clear broken code

WE = 1;//Open bit selection latch

P0 = 0XFB; //1111 1011

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = tabel[ge];//

DU = 0; //Latch segment selection data

delay(5);

}

//Timer 0 initialization

void timer0Init()

{

TR0 = 1; //Start timer 0

TMOD = 0X01; //Timer operating mode 1, 16-bit timer counting mode

TH0 = 0x4b;

TL0 = 0xfd; //Timing 50ms

/*

   How to set the time? For example, the timer is 50 microseconds

First of all, 50000 ÷ 1.085 = 46,082.94930875576. Starting from 0 and adding 19,453 times will overflow.     This calculation will have errors, but the impact is relatively small and can be ignored.

TH0 = (65535 - 46082) / 256; // Place the quotient in the upper eight bits

TL0 = (65535 - 46082) % 256; // Put the remainder in the lower eight bits

Or 65535 - 46082 = 19453

In hexadecimal we get: 4BFD

Binary gets: 0100 1011 1111 1101 

Put the obtained hexadecimal numbers into TH0 and TL0 respectively;

TH0 = 0x4b;

TL0 = 0xfd; //Timing 50ms

*/

}

void main(){//The main function itself will loop

uchar mSec, Sec; //Milliseconds and seconds storage variables

timer0Init();//Timer 0 initialization

while(1)

{

if(TF0 == 1)//Determine whether it overflows

{

TF0 = 0;//Software clears the overflow flag bit

TH0 = 0x4b;

TL0 = 0xfd; //Timing 50ms

mSec++;//50ms to

if(mSec == 20)

{

mSec = 0;

Sec++; //1 second is up

}

}

display(Sec); //Nigital tube display function

if(Sec > 59)

Sec = 0; // Clear seconds 

}

}