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


//long alarm_value=0x3800;
//long alarm_value=0x16000;

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

void alarm_convert(long alarmdata){               //4到20mA電流輸出程序 
  uchar i; 
  for(i=0;i<17;i++){                               //傳送高八位,從高位傳起
    P4DIR |= CLK;
    Delay(10);
    if(alarmdata&0x010000){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(10);
    P4DIR &=~CLK;
    Delay(10);
    alarmdata=alarmdata<<1;
  }
  P3DIR |= LATCH;
  Delay(10);
  P3DIR &=~LATCH;  
}    

void ideal_convert(int ad421data){               //報(bào)警信號(hào)電流輸出程序
  uchar i;
  for(i=0;i<16;i++){                               //傳送高八位,從高位傳起
    P4DIR |= CLK;
    Delay(30);
    if(ad421data&0x8000){
      P4DIR &=~DATA;
    }
    else{
      P4DIR |= DATA;
    }
    Delay(30);
    P4DIR &=~CLK;
    Delay(30);
    ad421data=ad421data<<1;
  }
  P3DIR |= LATCH;
  Delay(30);
  P3DIR &=~LATCH;  
}    
void current_config(void){
  P3OUT &=~0xc0;                                 //CVCON4低電平，芯片供電，latch輸出0
  P4OUT &=~0x03;                                 //CLK和DATA引腳輸出0
  P3DIR |= CVCON4;                               //低電平開始輸出，AD421開始工作
  //P3DIR &=~CVCON4;
  WDTCTL = WDTHOLD+WDTPW;
}

void main(void)
{ 
  uint da_value=0xA000;
  long alarm_value=0xA000;
  current_config();
  ideal_convert(da_value);
  _NOP();
  da_value=0x0000;
  ideal_convert(da_value);
  _NOP();
  alarm_convert(alarm_value);
  _NOP();
  alarm_value=0x10000;
  alarm_convert(alarm_value);
  while(1);  
}