C51 single-chip computer outputs multiple PWM through timer simulation

Preface

This blog post is based on STC89C52RC and keil5 C51 development;

If there is anything I haven't done, please give me some advice;

Things you need

This is done using Timer 0 (and Timer 1 as well).

Use P1.0~P1.3 to complete 4-way PWM output (different duty cycles);

code show as below:

#include

#define ENABLE 1

#define DISENABLE 0

typedef unsigned int uint16;

typedef unsigned char uchar8;

sbit P1_0 = P1^0;

sbit P1_1 = P1^1;

sbit P1_2 = P1^2;

sbit P1_3 = P1^3;

/*

Duty cycle time calculation:

Duty Cycle = High_Level_Time_P1_x/Cycle;

*/

uchar8 Cycle = 10; //Set PWM cycle: 10*timer overflow cycle (100us) = 1000us;

uchar8 High_Level_Time_P1_0 = 0; //The four global variables here control the high level time in each cycle;

uchar8 High_Level_Time_P1_1 = 0;

uchar8 High_Level_Time_P1_2 = 0;

uchar8 High_Level_Time_P1_3 = 0;   

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: 9C (decimal 156, that is, the overflow period of the timer is 100us);

3. Timer 0 is set to 8-bit auto-reload mode;

*/

void Time0_Init(void)

{

  TMOD = 0x02;

TH0 = 0x9C;

TL0 = 0x9C;

TR0 = ENABLE;

ET0 = ENABLE;

EA = ENABLE;

}

void Timer0_IT() interrupt 1

{ 

static uchar8 count_P1_0,count_P1_1,

  count_P1_2,count_P1_3; 

if(count_P1_0==High_Level_Time_P1_0)

{

P1_0 = 0;

}

count_P1_0++;

if(count_P1_0==Cycle)

{

P1_0= 1;

count_P1_0 = 0;

}

if(count_P1_1==High_Level_Time_P1_1)

{

P1_1 = 1;

}

count_P1_1++;

if(count_P1_1==Cycle)

{

P1_1= 0;

count_P1_1 = 1;

}

if(count_P1_2==High_Level_Time_P1_2)

{

count_P1_2=0;

}

count_P1_2++;

if(count_P1_2==Cycle)

{

P1_2 = 0;

count_P1_2=1;

}

if(count_P1_3==High_Level_Time_P1_3)

{

count_P1_3 = 0;

}

count_P1_3++;

if(count_P1_3==Cycle)

{

P1_3 = 1;

count_P1_3= 1;

}

}