// **********DAC8043.c

// Interface between MC68HC812 and DAC8043 12-bit DAC

// Uses SPI (for solution without SPI see DAB8043.c)

// Last modified 4/10/02 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 SPI-DAC8043 interface

// make  PS7,PS6,PS5 outputs, 

// SPI master data in, PS4, is not used

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

  DDRS = 0xE0;           // PS6=CLK=SPI clock out

  PORTS = 0x80;          // PS5=SRI=SPI master data out

/* bit SP0CR1

 7 SPIE = 0   no interrupts

 6 SPE  = 1   enable SPI

 5 SWOM = 0   regular outputs

 4 MSTR = 1   master

 3 CPOL = 0   output changes on fall, clock normally low

 2 CPHA = 0   and input clocked in on rise

 1 SSOE = 0   PS7 regular output DAC8043 LD

 0 LSBF = 0   most significant bit first */

  SP0CR1 = 0x50;

/* bit SP0CR2

 3 PUPS = 0   no internal pullups

 2 RDS  = 0   regular drive

 0 SPC0 = 0   normal mode */

  SP0CR2 = 0x00;

  SP0BR = 0x01; // 2 MHz

}

#define SPIF 0x80



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

// Output 12-bit code to DAC8043

// 0<=code<=4095

// uses SPI port

void DAC8043_Out(unsigned short code){ unsigned char dummy;

  SP0DR = code>>8;           // msbyte

  while((SP0SR&SPIF)==0);    // gadfly wait for SPIF

  dummy = SP0DR;             // clear SPIF

  SP0DR = code;              // lsbyte

  while((SP0SR&SPIF)==0);    // gadfly wait for SPIF

  dummy = SP0DR;             // clear SPIF

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

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

}