C51 MCU timer simulates single-channel output PWM

Preface

This blog post is developed based on STC89C52RC and Keil5 C51 environment;

If there are any deficiencies, please give me more advice;

Things Needed

Timer 0;

Pin P1.0;

code show as below:

#include

#define ENABLE 1

#define DISENABLE 0

typedef unsigned char uchar8;

sbit P1_0 = P1^0;

bit Flag = 0;

/*

Duty cycle time calculation:

Duty cycle = high level time / (high level time + low level time);

*/

//High level time (initial value: 0x02EE, i.e. decimal 750)

uchar8 Timer0_TH0_High_Level_Time = 0x02; //Timer 0 high eight-bit high level time;

uchar8 Timer0_TL0_High_Level_Time = 0xEE; //Timer 0 low eight bits high level time;

//Low level time (initial value: 0x00FA)

uchar8 Timer0_TH0_Low_Level_Time = 0x00; //Timer 0 high eight bits low level time;

uchar8 Timer0_TL0_Low_Level_Time = 0cFA; //Timer 0 low eight-bit low level time;

void Time0_Init(void);

void main()

{

  Time0_Heat();

  while(1);

}

/*

Timer configuration:

1. Assume that the crystal frequency of the microcontroller is 12MHz; then the timer accumulation period is 1us;

2. The initial value of the timer is: high level overflow time 0x02EE, that is, decimal 750; low level overflow time 0x00FA, that is, decimal 250;

3. Timer 0 is set to 16-bit auto-reload mode;

*/

void Time0_Init(void)

{

  TMOD = 0x01;

TH0 = Timer0_TH0_High_Level_Time; //The initial value is set to high level;

TL0 = Timer0_TL0_High_Level_Time;

TR0 = ENABLE;

ET0 = ENABLE;

EA = ENABLE;

Flag = 0;

P1_0 = 1;

}

void Timer0_IT() interrupt 1

{ 

if(Flag)

{

TH0 = Timer0_TH0_High_Level_Time;

TL0 = Timer0_TL0_High_Level_Time;

Flag = 0;

P1_0 = 1;

}

else

{

TH0 = Timer0_TH0_Low_Level_Time;

TL0 = Timer0_TL0_Low_Level_Time;

Flag = 1;

P1_0 = 0;

}

}