main.c

P89LV51RD2单片机PWM方波控制直流电机源码

/*
	main.c
	用PWM方波控制直流电机
*/


#include <reg51.h>


//定义I/O接口
sbit PWM = P1^6;		//PWM输出（电机）
sbit KEY1 = P2^0;		//按键1，使PWM方波占空比增加，电机加速
sbit KEY2 = P2^1;		//按键2，使PWM方波占空比减少，电机减速


//定义PWM最大级数
#define PWM_MAX		10


//定义PWM级数，分为0～PWM_MAX-1级
unsigned char PwmValue;


/*
函数：KeyScan()
功能：键盘扫描
返回：扫描到的键值
*/
unsigned char KeyScan()
{
	unsigned char k;
	k = '\0';
	if ( KEY1 == 0 ) k = '+';
	if ( KEY2 == 0 ) k = '-';
	return k;
}


/*
函数：T1_INT_SVC()
功能：定时器T1的中断服务函数
*/
void T1INTSVC() interrupt 3
{
	static unsigned char t = 0;
	TR1 = 0;
	TH1 = 0xFF;
	TL1 = 0x00;
	TR1 = 1;
	t++;
	if ( t >= PWM_MAX ) t = 0;
	if ( t <= PwmValue )
	{
		PWM = 1;
	}
	else
	{
		PWM = 0;
	}
}


/*
函数：Delay()
功能：延时0.01～2.56s
参数：
	t>0时，延时(t*0.01)s
	t=0时，延时2.56s
*/
void Delay(unsigned char t)
{
	do
	{
		TH0 = 0xDC;
		TL0 = 0x00;
		TR0 = 1;
		while ( !TF0 );
		TR0 = 0;
		TF0 = 0;
	} while ( --t != 0 );
}


/*
函数：SysInit()
功能：系统初始化
*/
void SysInit()
{
	TMOD &= 0xF0;
	TMOD |= 0x01;	//设置T0为16位定时器
	TMOD &= 0x0F;
	TMOD |= 0x10;	//设置T1为16位定时器
	PwmValue = PWM_MAX / 2;		//设置PWM初值
	PWM = 1;		//PWM管脚为高
	TH1 = 0xFF;
	TL1 = 0x00;		//定时器T1赋初值
	TR1 = 1;		//启动定时器T1
	ET1 = 1;		//使能T1中断
	EA = 1;			//使能总中断
}


void main()
{
	unsigned char k;
	SysInit();
	for (;;)
	{
	//键盘扫描
		for (;;)
		{
			Delay(5);
			k = KeyScan();
			if ( k != '\0' ) break;
		}
	//处理按键
		switch ( k )
		{
		case '+':
			if ( PwmValue < PWM_MAX-1 ) PwmValue++;
			break;
		case '-':
			if ( PwmValue > 0 ) PwmValue--;
			break;
		default:
			break;
		}
	//等待按键抬起
		for (;;)
		{
			Delay(5);
			if ( KeyScan() == '\0' ) break;
		}
	}
}