Hands-on teaching of 51 single-chip microcomputer | Lesson 3: Timer interrupt

1. Interruption

(1) External interruption

Open the general interrupt EA, select external interrupt EX0 or EX1, because IE is addressable, so directly operate on EX0 or EX1, then set IT0 (in TCOD) to level trigger or jump edge trigger (power-on default register 0, level trigger mode), then write the interrupt processing function to determine the number after interrupt according to the priority in the table below

(2) Timer interrupt

TMOD is the working mode register of the timer/counter.

TCON is the control register, which controls the start and stop of T0T1 and sets the overflow flag

If the working mode 01 is selected, TH TL is 16 bits

2^16=65536

(65536-N)/256 is equivalent to a bucket that can hold 65536, scooping out N units of water, and then adding 1 unit of water every 1us, and finally taking 5000us=50ms

Next is the detailed explanation of TCON

//Use the timer to replace the delay subfunction in the previous lesson

#include

#define uchar unsigned char 

#define uint unsigned int 

sbit dula=P2^6;

sbit temperature=P2^7;

flying number;

uchar code table[]={

0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71};

void Time0_delay();

void main()

{

temperature=1;

P0=0xc0;

temperature=0;

while(1)

{

for(num=0;num<16;num++)

{

game=1;

P0=table[num];

game=0;

Time0_delay();

}

}

}

void Time0_delay()

{

unsigned int i;

TMOD&=0xF0;//有效避免打乱高四位

TMOD|=0X01; //Final TMOD= ABCD 0001

for(i=0;i<20;i++)

{

TH0=(65536-50000)/256;

TL0=(65536-50000)%256;

TR0=1; //Start the timer

while(!TF0); //delay 50ms

TF0=0; // Overflow bit cleared

TR0=0; //turn off the timer

//Repeat 20 times for 1s

}

}

3. Code

//Comprehensive use of interrupts and timers

#include

#define uint unsigned int

#define uchar unsigned char

sbit dula=P2^6;

sbit temperature=P2^7;

sbit d1=P1^0;

fly num,tt;

uchar code table[]={

0x3f,0x06,0x5b,0x4f,

0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,

0x39,0x5e,0x79,0x71};

void main()

{

num=0;

tt=0;

TMOD=0x01; //Set timer 0 to working mode 1

//Assign initial value

TH0=(65536-50000)/256;

TL0=(65536-50000)%256;

EA=1; //Open the general interrupt

ET0=1; // Enable the interrupt of timer 0

TR0=1; //Start timer 0, it will keep running as long as it is turned on

temperature=1;

P0=0xfe; //First digital tube

temperature=0;

dula=1; P0=0x3f; //To avoid garbled code, assign the initial value 0

game=0;

while(1)

{

//20 times is 1s, perform 1 if

if(tt==20)

{

tt=0;

  num++;

if(num==16)

num=0;//clear!!!

game=1;

P0=table[num];

game=0;

}

}

}

/*void delay(uint z)

{

fly x,y;

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

for(y=110;y>0;y--);

}*/

void exter0()interrupt 1

{

TH0=(65536-50000)/256;

TL0=(65536-50000)%256;

tt++;

}

4. Summary