chap3.c

Motorola 6812芯片开发的接口程序。

// Chapter 3 6812 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

// Program 3.1. A software function that outputs to a simple printer.
void Output(unsigned char LETTER) { unsigned short cnt;
    PORT=LETTER;     /* sets Port outputs */
    Pulse();         /* pulses GO */
    for(cnt=0,cnt<10000,cnt++);   /* Wait for 100 ms */
}  

// Program 3.2. A software function that inputs from an A/D.
unsigned char Input(void); { int dummy;
    Pulse();                  /* pulses GO       */
    dummy=1000;               /* Wait for 5us    */
    return(PORT);             /* Read A/D result */
}  

// Program 3.4. Assembly language routines to initialize and output to a printer.
// MC68HC812A4
void Init(void){
    DDRJ=0xFF; // outputs
    DDRH=0x01;
    PORTH=1;} // GO=1
void Out(unsigned char value){
unsigned int n;
    PORTJ=value;
    PORTH=0;  // GO=0
    PORTH=1;  // GO=1
    for(n=0;n<40000;n++);}

// Program 3.7. 6811 or 6812 C language routine to create an accurate time delay.
// 6811 or 6812, numCycles can range from 25 to 32767 
void Wait(short numCycles){ 
short EndT;  // TCNT at the end of the delay
    EndT=TCNT+numCycles; 
    while(EndT-(short)TCNT>0);} // wait until TCNT passes EndT

// Program 3.9. C language routines to initialize and read from an A/D.
// MC68HC812A4
void Init(void){
    DDRJ=0x00; // PortJ DATA
    DDRH=0x01; // PH0 GO
    PORTH=0;}  // GO=0
unsigned char In(void){int n;
    PORTH=1;  // GO=1
    PORTH=0;  // GO=0
    for(n=0;n<8;n++);
    return(PORTJ);}

// Program 3.11. C language routines to initialize and read from a keyboard.
// MC68HC812A4
void Init(void){ // PJ7=STROBE
    DDRJ=0x00;   // PJ6-0 DATA
    KPOLJ=0x80;  // rise on PJ7
    KWIFJ=0x80;} // clear flag
unsigned char In(void){ 
    while((KWIFJ&0x80)==0); // wait
    KWIFJ=0x80;  // clear flag
    return(PORTJ&0x7F);}

// Program 3.13. C language routines to initialize and read from an A/D.
// MC68HC812A4
void Init(void){ // PJ1=DONE in
    DDRJ=0x01;   // PJ0=GO out
    KPOLJ=0x02;  // rise on PJ1
    DDRH=0x00;   // PH DATA in
    PORTJ=0;}    // GO=0
unsigned char In(void){ 
    KWIFJ=0x02;  // clear flag
    PORTJ=1;     // GO pulse
    PORTJ=0;
    while((KWIFJ&0x02)==0); 
    return(PORTH);}

// Program 3.16. Handshaking C language routines to initialize and read from a sensor.
// MC68HC812A4
void Init(void){ // PJ1=READY in
    DDRJ=0x01;   // PJ0=ACK out
    KPOLJ=0x02;  // rise on PJ1
    DDRH=0x00;   // PH DATA in
    KWIFJ=0x02;  // clear flag1
    PORTJ=0X01;} // ACK=1
unsigned char In(void){ 
unsigned char data;
    while((KWIFJ&0x02)==0); 
    PORTJ=0;     // ACK=0
    data=PORTH;  // read data
    KWIFJ=0x02;  // clear flag
    PORTJ=0x01;  // ACK=1
    return(data);}

// Program 3.18. Handshaking C language routines to initialize and write to a printer.
// MC68HC812A4
void Init(void){ // PJ1=READY in
    DDRJ=0x01;   // PJ0=START out
    KPOLJ=0x02;  // rise on PJ1
    DDRH=0xFF;   // PH DATA out
    PORTJ=0X01;} // START=1
void Out(unsigned char data){
    KWIFJ=0x02;  // clear flag
    PORTJ=0;     // START=0
    PORTH=data;  // write data
    PORTJ=0x01;  // START=1
    while((KWIFJ&0x02)==0);}

// Program 3.20. C language initialization of the DS1620
// MC68HC812A4/MC68HC912B32
void Init(void){ // PS7=RST=0
    DDRS=0xE0;   // PS6=CLK=1
    PORTS=0x60;} // PS5=DQ=1

// Program 3.22. C language helper functions for the DS1620
// MC68HC812A4/MC68HC912B32
void out8(char code){ int n;
  for(n=0;n<8;n++){
     PORTS &= 0xBF;   // PS6=CLK=0
     if(code&0x01)  
       PORTS |= 0x20; // PS5=DQ=1
     else
       PORTS &= 0xDF; // PS5=DQ=0
     PORTS |= 0x40;   // PS6=CLK=1
     code = code>>1;}}
void start(void){
   PORTS |= 0x80;   // PS7=RST=1
   out8(0xEE);
   PORTS &= 0x7F;}  // PS7=RST=0
void stop(void){
   PORTS |= 0x80;   // PS7=RST=1
   out8(0x22);
   PORTS &= 0x7F;}  // PS7=RST=0

// Program 3.24. C language functions to set the configuration register on the DS1620
// MC68HC812A4/MC68HC912B32
void config(char data){
   PORTS |= 0x80;   // PS7=RST=1
   out8(0x0C);
   out8(data);
   PORTS &= 0x7F;}  // PS7=RST=0

// Program 3.27. C language functions to set the threshold registers on the DS1620
// MC68HC812A4/MC68HC912B32
void out9(int code){ int n;
  for(n=0;n<9;n++){
     PORTS &= 0xBF;   // PS6=CLK=0
     if(code&0x01)  
       PORTS |= 0x20; // PS5=DQ=1
     else
       PORTS &= 0xDF; // PS5=DQ=0
     PORTS |= 0x40;   // PS6=CLK=1
     code = code>>1;}}
void WriteTH(int data){
   PORTS |= 0x80;   // PS7=RST=1
   out8(0x01);
   out9(data);
   PORTS &= 0x7F;}  // PS7=RST=0
void WriteTL(int data){
   PORTS |= 0x80;   // PS7=RST=1
   out8(0x02);
   out9(data);
   PORTS &= 0x7F;}  // PS7=RST=0

// Program 3.29. C language functions to read the configuration register on the DS1620
// MC68HC812A4/MC68HC912B32
unsigned char in8(void){ int n; 
unsigned char result;
  DDRS &= 0xDF; // PS5=DQ input
  for(n=0;n<8;n++){
     PORTS &= 0xBF;   // PS6=CLK=0
     result = result>>1;
     if(PORTS&0x20)  
       result |= 0x80; // PS5=DQ=1
     PORTS |= 0x40;}  // PS6=CLK=1
   DDRS |= 0x20; // PS5=DQ output
   return result;}
unsigned char ReadConfig(void){
unsigned char value;
   PORTS |= 0x80;   // PS7=RST=1
   out8(0xAC);
   value=in8();
   PORTS &= 0x7F;   // PS7=RST=0
   return value;}

// Program 3.31. C language 9-bit read helper function for the DS1620
// MC68HC812A4/MC68HC912B32
unsigned int in9(void){ int n; 
unsigned int result=0;
  DDRS &= 0xDF; // PS5=DQ input
  for(n=0;n<9;n++){
     PORTS &= 0xBF;   // PS6=CLK=0
     result = result>>1;
     if(PORTS&0x20)  
       result |= 0x0100; // PS5=DQ=1
     PORTS |= 0x40;}  // PS6=CLK=1
   DDRS |= 0x20; // PS5=DQ output
   return result;}

// Program 3.32. C language functions to read the temperatures from the DS1620
// MC68HC812A4/MC68HC912B32
unsigned int ReadTH(void){
unsigned int value;
   PORTS |= 0x80;   // PS7=RST=1
   out8(0xA1);
   value=in9();
   PORTS &= 0x7F;   // PS7=RST=0
   return value;}
unsigned int ReadTL(void){
unsigned int value;
   PORTS |= 0x80;   // PS7=RST=1
   out8(0xA2);
   value=in9();
   PORTS &= 0x7F;   // PS7=RST=0
   return value;}
unsigned int ReadT(void){
unsigned int value;
   PORTS |= 0x80;   // PS7=RST=1
   out8(0xAA);
   value=in9();
   PORTS &= 0x7F;   // PS7=RST=0
   return value;}