control.c

通过调节一个可变电阻得到变化的电压来模拟一个湿度度传感器

#include <reg51.h>
#include "commons.h"

sbit _p32 = P3^2;
sbit _p30 = P3^0;
sbit _p25 = P2^5;
sbit _p26 = P2^6;
sbit _p27 = P2^7;

unsigned char _pcount = 0;		   //定时中断总次数，每100次为一个输出总周期
unsigned char _pout = 0;		   //占空比对应的定时中断次数（低电平有效的周期数）
float _sigma_i = 0.0;			   //PWM占空比

unsigned int ad();
void da(unsigned int value);	   //串口DA转变
unsigned int filter(unsigned int value, unsigned char flt_idx);	 //数字滤波函数
void ctrl_init(void) {			   //定时器中断初始化
	TMOD = 0x02;				   //定时器0方式2
	TH0  = 0;
	TL0  = 0;	
	ET0  = 1;
	TR0  = 1;
	EA   = 1;
}

void _ctrl_proc(void) interrupt 1 {	 //比例控制
	if (++_pcount == 100) {
		_pcount = 0;
		_pout = (unsigned char)(100.0 * (1.0 - _sigma_i)); //每个总周期结束时确定下次的输出周期
	}
	if (_pcount < _pout) {			  //判断定时中断次数是否达到占空比对应的中断次数
		_p25 = 1;	
	} else {
	 	_p25 = 0;
	}
}

void ctrl_routine(void) {
	char led_buf[6];
	unsigned int value;
	unsigned char d;
	
	value = filter(ad(), _menu_value[3]);//数字滤波
	da(value);                           //D/A转换

	//超限报警
	if (value > _menu_value[0]) {
		_p26 = 0;
		_p27 = 1;
	} else if (value <= _menu_value[0] && value >= _menu_value[1]) {
	 	_p26 = 1;
		_p27 = 1;
	} else {
		_p26 = 1;
	 	_p27 = 0;
	}	
	
	//根据比例度确定输出占空比_sigma_i
	if (value > _menu_value[2]) {		    //大于控制目标时，占空比定为0
		_sigma_i = 0;
	} else {
	 	d = (int)(100.0 * (float)value / (float)_menu_value[2]); //计算是否进入临届比例度
		if (d < _menu_value[4]) {			//若没有进入，占空比定为100%
		 	_sigma_i = 1.0;
		} else {							//否则，计算占空比
		 	_sigma_i = (float)(100 - d) / (float)(100 - _menu_value[4]);
		}
	}

	if (_menu_status == MENU_OFF) {
		led_buf[0] = '^';
		to_string(&led_buf[1], 5, value);
		print(led_buf);			
	}
}