[嵌入式]蓝桥杯单片机-DAC-用板载板载PCF8591芯片在D/A引脚上输出指定的电压

题目

1.控制板载PCF8591芯片在D/A引脚上输出指定的电压
2.数码管前三位显示输入数据0-255，后两位显示输出的电压值
3.按下按键S4则输入数据+40，按下S5则输入数据-40

main.c

//@mzw
//控制板载PCF8591芯片在D/A引脚上输出指定的电压
//数码管前三位显示输入数据0-255，后两位显示输出的电压值
//按下按键S4则输入数据+40，按下S5则输入数据-40
#include<reg52.h>
#include<iic.h>
#include<intrins.h>
#include<absacc.h>

sbit hc138_A=P2^5;
sbit hc138_B=P2^6;
sbit hc138_C=P2^7;
sbit S7 = P3^0;
sbit S6 = P3^1;
sbit S5 = P3^2;
sbit S4 = P3^3;

unsigned char shuzi[10]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90}; //0-9
unsigned char shuzi1[10]={0x40,0x79,0x24,0x30,0x19,0x12,0x02,0x78,0x00,0x10};//0-9//含小数点

unsigned char key_value = 0;
unsigned char input_v = 0;	//输出电压范围     0-255
int real_v = 0;	//实际输出电压0-5v的10倍（方便数码管显示）

/*****配置138译码器*****/
void HC138(unsigned int n)
{
    switch(n)
    {
        case 4:
        hc138_A=0 ; hc138_B=0 ; hc138_C=1; break;
        case 5:
        hc138_A=1 ; hc138_B=0 ; hc138_C=1; break;
        case 6:
        hc138_A=0 ; hc138_B=1 ; hc138_C=1; break;
        case 7:
        hc138_A=1 ; hc138_B=1 ; hc138_C=1; break;
    }
}
/*****延时函数*****/
void delay(unsigned int k)
{
    while(k--);
}

/*****数码管显示函数*****/
void Display()
{
	char x = 0x01;
	int i = 0;
	for(i = 1;i<=8 ;i++)
	{
		HC138(6);
		P0 = x;
		x = _crol_(x,1);
		HC138(7);
		P0 = 0xff;delay(20);	//数码管消隐放到这个地方好一点
		switch (i)
		{
			case 1 :P0 = shuzi[input_v/100]; break;
			case 2 :P0 = shuzi[input_v/10%10]; break;
			case 3 :P0 = shuzi[input_v%10]; break;
			case 4 :P0 = 0xff; break;
			case 5 :P0 = 0xff; break;
			case 6 :P0 = 0xff; break;
			case 7 :P0 = shuzi1[real_v / 10]; break;
			case 8 :P0 = shuzi[real_v % 10]; break;
		}
		delay(500);P0 = 0xff;
	}
}

/*****按键扫描函数*****/
void key_scan()
{
	if((S4 == 0) || (S5 == 0) || (S6 == 0) || (S7 == 0))	//其中一个按键被按下则为1
	{
		delay(100);		//延时消抖
		if(S4 == 0)	key_value = 4;
		if(S5 == 0)	key_value = 5;
		if(S6 == 0)	key_value = 6;
		if(S7 == 0)	key_value = 7;
		while((S4 == 0) || (S5 == 0) || (S6 == 0) || (S7 == 0))//等待按键松开
		{
			Display();
		}
	}
}

void Key_real()
{
	if(key_value == 4)
	{
		input_v	= input_v + 40;
	}
	if(key_value == 5)
	{
		input_v	= input_v - 40;
	}
	key_value = 0;
}

/*****	DAC相关	*****/
/* 在D/A引脚输出0-5v电压*/
/*	参数dat范围0-255，对应电压0-5v	*/
void dac_pcf8591(unsigned char dat)
{
	IIC_Start();
	IIC_SendByte(0x90);
	IIC_WaitAck();
	IIC_SendByte(0x40); 
	IIC_WaitAck();
	IIC_SendByte(dat);
	IIC_WaitAck();
	IIC_Stop();
}

void main()
{
	HC138(5);
	P0=0x00;	//蜂鸣器和继电器初始化、、全关
	HC138(4);
	P0= 0xff;	//LED小灯初始化、、全关
	while(1)
	{
		key_scan();
		Key_real();
		dac_pcf8591(input_v);
		real_v = input_v * 5 * 10 / 255;
		Display();
	}
}

iic.c

/*
  程序说明: IIC总线驱动程序
  软件环境: Keil uVision 4.10 
  硬件环境: CT107单片机综合实训平台 8051，12MHz
  日    期: 2011-8-9
  该程序为蓝桥杯单片机比赛官方所提供的参考代码
*/

#include "reg52.h"
#include "intrins.h"

#define somenop {_nop_();_nop_();_nop_();_nop_();_nop_();}    


#define SlaveAddrW 0xA0
#define SlaveAddrR 0xA1

//总线引脚定义
sbit SDA = P2^1;  /* 数据线 */
sbit SCL = P2^0;  /* 时钟线 */


//总线启动条件
void IIC_Start(void)
{
	SDA = 1;
	SCL = 1;
	somenop;
	SDA = 0;
	somenop;
	SCL = 0;	
}

//总线停止条件
void IIC_Stop(void)
{
	SDA = 0;
	SCL = 1;
	somenop;
	SDA = 1;
}

//应答位控制
void IIC_Ack(bit ackbit)
{
	if(ackbit) 
	{	
		SDA = 0;
	}
	else 
	{
		SDA = 1;
	}
	somenop;
	SCL = 1;
	somenop;
	SCL = 0;
	SDA = 1; 
	somenop;
}

//等待应答
bit IIC_WaitAck(void)
{
	SDA = 1;
	somenop;
	SCL = 1;
	somenop;
	if(SDA)    
	{   
		SCL = 0;
		IIC_Stop();
		return 0;
	}
	else  
	{ 
		SCL = 0;
		return 1;
	}
}

//通过I2C总线发送数据
void IIC_SendByte(unsigned char byt)
{
	unsigned char i;
	for(i=0;i<8;i++)
	{   
		if(byt&0x80) 
		{	
			SDA = 1;
		}
		else 
		{
			SDA = 0;
		}
		somenop;
		SCL = 1;
		byt <<= 1;
		somenop;
		SCL = 0;
	}
}

//从I2C总线上接收数据
unsigned char IIC_RecByte(void)
{
	unsigned char da;
	unsigned char i;
	
	for(i=0;i<8;i++)
	{   
		SCL = 1;
		somenop;
		da <<= 1;
		if(SDA) 
		da |= 0x01;
		SCL = 0;
		somenop;
	}
	return da;
}

iic.h

#ifndef _IIC_H
#define _IIC_H

//函数声明
void IIC_Start(void); 
void IIC_Stop(void);  
void IIC_Ack(bit ackbit); 
void IIC_SendByte(unsigned char byt); 
bit IIC_WaitAck(void);  
unsigned char IIC_RecByte(void); 

#endif

iic.c和iic.h文件为蓝桥杯单片机比赛官方所提供的例程