DC motor speed regulation experiment based on 51 single chip microcomputer

1. Experimental Principle

PWM: Pulse Width Modulation. In an inertial system, the required analog quantity can be equivalently obtained by modulating the width of a series of pulses. It is often used for motor speed regulation, light brightness adjustment, etc.

This experiment is essentially the same as the previous LED breathing light (timer implementation) experiment. You can understand and learn from the previous article, so I will not go into details here. (The following figure refers to the LED breathing light experiment)

2. Key Code

void Timer0_Routine() interrupt 1

{

TL0 = 0x66;

TH0 = 0xFF;

Counter++;

Counter%=100; //The count value range is limited to 0~99

if(Counter< Compare) //Count value is less than comparison value

{

Motor=1; //Output 1: Motor rotates (ULN2003 chip is a 7-way inverter circuit, that is, when the input terminal is high level, the output terminal of ULN2003 is low level)

}

else //The count value is greater than the comparison value

{

Motor=0; //output 0, motor stops

}

sbit Motor=P1^0;

unsigned char Counter,Compare; //Count value and comparison value, used to output PWM

unsigned char KeyNum,Speed;

//Main function

void main()

{

Timer0_Init();

while(1)

{

KeyNum=Key();

if(KeyNum==1)

{

Speed++;

Speed%=4;

if(Speed==0){Compare=0;} //Change the comparison value and PWM duty cycle

if(Speed==1){Compare=60;}

if(Speed==2){Compare=75;}

if(Speed==3){Compare=100;}

}

}

}

A PWM wave of a certain period is realized through a timer, and the duty cycle of the high level is changed by changing the comparison value Compare, thereby changing the speed of the motor.