main3.c

基于msp430的AD421电流控制芯片程序

//P4.7－－－SDA
//P4.6－－－SCL
#include "msp430x44x.h"
#define LATCH   0X80;                              //16CLK引脚，P3.7
#define CLK     0X01;                              //TXD2引脚，P4.0
#define DATA    0x02;                              //RXD2引脚，P4.1
#define CVCON4  0x40;                              //CVCON4引脚，P3.6
#define uchar unsigned char
#define uint unsigned int

int da_value=0xB000;
long alarm_value=0x3800;
//long alarm_value=0x16000;

void Delay(int m)
{
   while(m-- > 0);
}

void alarm_convert(long alarmdata){               //4到20mA电流输出程序 
  uchar dataH2,dataH,dataL,i;
  dataH2=(alarmdata&0x10000)>>16;
  dataH=(alarmdata&0x00FF00)>>8;
  dataL=(alarmdata&0x0000FF);
  
  P4DIR |= CLK;                                  //传送最高位
  Delay(30);
  if(dataH2&0x01){
    P4DIR &=~DATA;
  }
  else{
    P4DIR |= DATA;
  }
  Delay(30);
  P4DIR &=~CLK;
  Delay(30);
  
  for(i=0;i<8;i++){                               //传送高八位,从高位传起
    P4DIR |= CLK;
    Delay(30);
    if(dataH&0x80){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(30);
    P4DIR &=~CLK;
    Delay(30);
    dataH=dataH<<1;
  }
  for(i=0;i<8;i++){                               //传送低八位,从高位传起
    P4DIR |= CLK;
    Delay(30);
    if(dataL&0x80){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(30);
    P4DIR &=~CLK;
    Delay(30);
    dataL=dataL<<1;
  }  
  P3DIR |= LATCH;
  Delay(30);
  P3DIR &=~LATCH;  
}    

void ideal_convert(int ad421data){               //报警信号电流输出程序
  uchar dataH,dataL,i;
  dataH=(ad421data&0xFF00)>>8;
  dataL=(ad421data&0x00FF);
  for(i=0;i<8;i++){                               //传送高八位,从高位传起
    P4DIR |= CLK;
    Delay(30);
    if(dataH&0x80){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(30);
    P4DIR &=~CLK;
    Delay(30);
    dataH=dataH<<1;
  }
  for(i=0;i<8;i++){                               //传送低八位,从高位传起
    P4DIR |= CLK;
    Delay(30);
    if(dataL&0x80){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(30);
    P4DIR &=~CLK;
    Delay(30);
    dataL=dataL<<1;
  }  
  P3DIR |= LATCH;
  Delay(30);
  P3DIR &=~LATCH;  
}    

void main(void)
{ 
  P3OUT &=~0xc0;                                 //CVCON4低电平，芯片供电，latch输出0
  P4OUT &=~0x03;                                 //CLK和DATA引脚输出0
  P3DIR |= CVCON4;                               //低电平开始输出，AD421开始工作
  //P3DIR &=~CVCON4;
  WDTCTL = WDTHOLD+WDTPW;
  ideal_convert(da_value);
  _NOP();
  da_value=0x0000;
  ideal_convert(da_value);
  _NOP();
  alarm_convert(alarm_value);
  while(1);  
}