chap7.c

摩托罗拉Mc6805利程

// Chapter 7 6805 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999



// Program 7.19. C language initialization for a D/A interface using the SPI.
// MC68HC05C8
void DACInit(void){ // PD5=LD=1
   DDRD|=0x38;  // PD4=CLK=SPI clock out
   PORTD|=0x20; // PD3=SRI=SPI master out
/* bit SPCR
 7 SPIE = 0   no interrupts
 6 SPE  = 1   enable SPI
 4 MSTR = 1   master
 3 CPOL = 0   output changes on fall, 
 2 CPHA = 0   clock normally low
 1 SPR1 = 0   1 MHz operation
 0 SPR0 = 0    */
   SPCR=0x50;}

// Program 7.20. C language function for a D/A interface using the SPI.
// MC68HC05C8
#define SPRF 0x80
void DACout(unsigned int code){ 
unsigned char dummy;
   SPDR=0x00FF &(code>>8); // msbyte
   while((SPSR&SPIF)==0); // gadfly wait 
   dummy=SPDR;            // clear SPIF
   SPDR=0x00FF& code;     // lsbyte
   while((SPSR&SPIF)==0); // gadfly wait 
   dummy=SPDR;            // clear SPIF
   PORTD &= ~0x20;         // PD5=LD=0

// Program 7.21. C language initialization for an A/D interface using the SPI.
// MC68HC05C8
void ADCInit(void){ // PD5=CS=1
   DDRD|=0x38;  // PD4=SCLK=SPI clock out
   PORTD|=0x20; // PD3=DIN=SPI master out
/* bit SPCR        PD2=DOUT=SPI master in
 7 SPIE = 0   no interrupts
 6 SPE  = 1   enable SPI
 4 MSTR = 1   master
 3 CPOL = 0   output changes on fall, 
 2 CPHA = 0   clock normally low
 1 SPR1 = 0   1 MHz operation
 0 SPR0 = 0    */
   SPCR=0x50;} 
#define CH0 0x9F
#define CH1 0xDF
#define CH2 0xAF
#define CH3 0xEF

// Program 7.22. C language function for an A/D interface using the SPI.
// MC68HC05C8
unsigned int ADCin(unsigned char code){  
unsigned int data;
   PORTD &= ~0x20; // PD5=CS=0
   SPDR=code;    // set channel,mode
   while((SPSR&0x80)==0); // gadfly wait 
   data=SPDR;    // clear SPIF
   SP0DR=0;       // start SPI
   while((SPSR&0x80)==0); // gadfly wait 
   data=SPDR<<8; // msbyte of A/D
   SPDR=0;       // start SPI
   while((SPSR&0x80)==0); // gadfly wait 
   data+=SPDR;    // lsbyte of A/D
   PORTD |= 0x20; // PD5=CS=1
   return data>>3;} // right justify

// Program 7.23. C language initialization of a temperature sensor interface using the SPI.
// MC68HC812A4/MC68HC912B32 only

// Program 7.24. C language helper functions for a temperature sensor interface using the SPI.
// MC68HC812A4/MC68HC912B32 only

// Program 7.25. C language functions for a temperature sensor interface using the SPI.
// MC68HC812A4/MC68HC912B32 only