// **********dab8043.c

// Interface between MC68HC812 and DAC8043 12-bit DAC

// does not use SPI (for SPI interface see dac8043.c)

// Last modified 1/15/02 by Jonathan W. Valvano

 

// Copyright 2002 by Jonathan W. Valvano, valvano@uts.cc.utexas.edu 

//    You may use, edit, run or distribute this file 

//    as long as the above copyright notice remains 



//******** DAC8043_Init *************** 

// Initialize 6812-DAC8043 interface

// make  PS7,PS6,PS5 outputs

void DAC8043_Init(void){ // PS7=LD=1

  DDRS = 0xE0;           // PS6=CLK=0

  PORTS = 0x80;          // PS5=SRI=0

}



//******** DAC8043_Out *************** 

// Output 12-bit code to DAC8043

// 0<=code<=4095

// uses bit banging technique

void DAC8043_Out(unsigned short code){ int n;

  for(n=0;n<12;n++){

    PORTS &= ~0x40;   // PS6=CLK=0

    if(code&0x0800)   // msb in bit 11

      PORTS |= 0x20;  // PS5=SRI=1

    else

      PORTS &= ~0x20; // PS5=SRI=0

    PORTS |= 0x40;    // PS6=CLK=1

    code = code<<1;

  }

  PORTS &= ~0x40;     // PS6=CLK=0

  PORTS &= ~0x80;     // PS7=LD=0

  PORTS |= 0x80;      // PS7=LD=1

}