藍橋杯單片機必備知識-----(4)pcf8591--DAC

藍橋杯單片機必備知識-----(4)pcf8591–DAC

IIC.H檔案中添加

dac_pcf8591(unsigned char dat)

IIC.C檔案中添加

void dac_pcf8591(unsigned char dat)
{
	IIC_Start();			//總線啟動條件
	IIC_SendByte(0x90);		//通過I2C總線發送資料
	IIC_WaitAck();			//等待應答
	IIC_SendByte(0x40);		//通過I2C總線發送資料
	IIC_WaitAck();			//等待應答
	
	IIC_SendByte(dat);
	IIC_WaitAck();
	IIC_Stop();
}

主函式 main.c中添加

dac_pcf8591(dac_value);

注：該ADC模塊只能通過0~255來輸出最大4.85V，顯示時應該需要適當的轉換

測驗結果：（測驗結果沒有轉換）

完整代碼粘貼

IIC.H

#ifndef _IIC_H
#define _IIC_H

void IIC_Start(void); 
void IIC_Stop(void);  
bit IIC_WaitAck(void);  
void IIC_SendAck(bit ackbit); 
void IIC_SendByte(unsigned char byt); 
unsigned char IIC_RecByte(void); 

unsigned char init_pcf8591(void);
unsigned char adc_pcf8591(void);

void dac_pcf8591(unsigned char dat);

#endif

IIC.C

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

#define DELAY_TIME 5

#define SlaveAddrW 0xA0
#define SlaveAddrR 0xA1

//總線引腳定義
sbit SDA = P2^1;  /* 資料線 */
sbit SCL = P2^0;  /* 時鐘線 */

void IIC_Delay(unsigned char i)
{
    do{_nop_();}
    while(i--);        
}
//總線啟動條件
void IIC_Start(void)
{
    SDA = 1;
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SDA = 0;
    IIC_Delay(DELAY_TIME);
    SCL = 0;	
}

//總線停止條件
void IIC_Stop(void)
{
    SDA = 0;
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SDA = 1;
    IIC_Delay(DELAY_TIME);
}

//發送應答
void IIC_SendAck(bit ackbit)
{
    SCL = 0;
    SDA = ackbit;  					// 0：應答，1：非應答
    IIC_Delay(DELAY_TIME);
    SCL = 1;
    IIC_Delay(DELAY_TIME);
    SCL = 0; 
    SDA = 1;
    IIC_Delay(DELAY_TIME);
}

//等待應答
bit IIC_WaitAck(void)
{
    bit ackbit;
	
    SCL  = 1;
    IIC_Delay(DELAY_TIME);
    ackbit = SDA;
    SCL = 0;
    IIC_Delay(DELAY_TIME);
    return ackbit;
}

//通過I2C總線發送資料
void IIC_SendByte(unsigned char byt)
{
    unsigned char i;

    for(i=0; i<8; i++)
    {
        SCL  = 0;
        IIC_Delay(DELAY_TIME);
        if(byt & 0x80) SDA  = 1;
        else SDA  = 0;
        IIC_Delay(DELAY_TIME);
        SCL = 1;
        byt <<= 1;
        IIC_Delay(DELAY_TIME);
    }
    SCL  = 0;  
}

//從I2C總線上接收資料
unsigned char IIC_RecByte(void)
{
    unsigned char i, da;
    for(i=0; i<8; i++)
    {   
    	SCL = 1;
	IIC_Delay(DELAY_TIME);
	da <<= 1;
	if(SDA) da |= 1;
	SCL = 0;
	IIC_Delay(DELAY_TIME);
    }
    return da;    
}

//DAC
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();
}

//ADC

void init_pcf8591()
{
	IIC_Start();
	IIC_SendByte(0x90);
	IIC_WaitAck();
	IIC_SendByte(0x03);
	IIC_WaitAck();
	IIC_Stop();
}

unsigned char adc_pcf8591()
{
	unsigned char temp;
	IIC_Start();
	IIC_SendByte(0x91);
	IIC_WaitAck();
	temp = IIC_RecByte();
	IIC_SendAck(1);
	IIC_Stop();
	
	return temp;
}

MAIN.C

#include <stc15f2k60s2.h>
#include "iic.h"

#define uint unsigned int
#define uchar unsigned char
	
uchar tab[] = {0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};
uchar dspbuf[8] = {10,10,10,10,10,10,10,10};
uchar adc_flag,dac_value,adc_value;
uchar s6 = 0,s7 = 0;

void load();
void display();
void read_key();

void cls()
{
	P2 = (P2 & 0x1f) | 0x80;
	P0 = 0xff;
	P2 = 0x1f;
	
	P2 = (P2 & 0x1f) | 0xa0;
	P0 = 0x00;
	P2 = 0x1f;
}

void main()
{
	cls();
	AUXR = 0xc0;
	TMOD = 0x00;
	TL0 = 0xcd;
	TH0 = 0xd4;
	
	TR0 = 1;
	ET0 = 1;
	EA = 1;
	init_pcf8591();
	while(1)
	{
		if(adc_flag){adc_value = adc_pcf8591();adc_flag = 0;}
		read_key();
	}
}

void time0() interrupt 1
{
	static unsigned char intr = 0;
	intr++;
	if(intr = 50){intr = 0; adc_flag = 1;}
	display();
}

void load()
{
	if(s7)
	{
		s7 = 0;
		dac_value = 105.15; //2v
		dac_pcf8591(dac_value);
	}
	if(s6)
	{
		s6= 0;
		dac_value = 210.31; //4v
		dac_pcf8591(dac_value);
	}
	dspbuf[1] = dac_value / 100;
	dspbuf[2] = dac_value %100/10;
	dspbuf[3] = dac_value %10;
	
	dspbuf[5] = adc_value / 100;
	dspbuf[6] = adc_value %100/10;
	dspbuf[7] = adc_value %10;
	
}

void read_key()
{
	static unsigned char state = 0;
	uchar temp;
	temp = P3 & 0x0f;
	switch(state)
	{
		case 0:
		{
			if(P3 != 0x0f) state = 1;
		}break;
		case 1:
		{
			if(P3 != 0x0f)
			{
				switch(temp)
				{
					case 0x0e:{s7= (s7 + 1) % 2; state = 2;}break;
					case 0x0d:{s6= (s6 + 1) % 2; state = 2;}break;
				}
			}
			else state = 0;
		}break;
		case 2:
		{
			if(P3 == 0xff) state = 0;
		}break;
	}
}

void display()
{
	static unsigned char dspcom = 0;
	
	load();
	
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = 0xff;
	P2 = 0x1f;
	
	P2 = (P2 & 0x1f) | 0xc0;
	P0 = 1<<dspcom;
	P2 = 0x1f;
	
	P2 = (P2 & 0x1f) | 0xe0;
	P0 = tab[dspbuf[dspcom]];
	P2 = 0x1f;
	
	if(++dspcom == 8) dspcom = 0;
}