chap1.c

Motorola 6812芯片开发的接口程序。

// Chapter 1 6812 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

// Program 1.2. 6812 software to enable the timer system.
#define TSCR *(unsigned char volatile*)(0x0086)
#define TMSK2 *(unsigned char volatile*)(0x008D)
   TSCR = 0x80;  // enable TCNT
   TMSK2= 0x33;  // 1_s clock

//  Program 1.4. 6812 C software that programs its internal EEPROM.
#define EraseAll  0x06
#define EraseWord 0x16
#define EraseRow  0x0E
#define ProgWord  0x02
int Program(char command, volatile int *address, int data){ 
char oldEEPROT; int Endt;
    oldEEPROT=EEPROT;   // read and save
    EEPROT=0;
    EEPROG=command;     // BULKP=0, ELAT=1, EEPRGM=0
    EEPROG++;           // sets EEPRGM=1
    (*address)=data;    // latch address, data
    Endt=TCNT+10000;    // TCNT value 10 ms from now
    while(EndT-TCNT>0); // wait until TCNT passes EndT
    EEPROG=0;           // normal mode
    EEPROT=oldEEPROT;   // restore
    return (*address);} // value at that address

//  Program 1.5. Helper functions used to program MC68HC91B32 flash EEPROM.
void wait(int time){ int Endt;  // works for time<32678
    Endt=TCNT+time;     // TCNT value time cycles from now
    while(EndT-TCNT>0); // wait until TCNT passes EndT
}
int IsFlashErased(void){int *pt; // returns true if flash erased
    for(pt=(int*)0x8000;pt<(int*)0xf800;pt++){
       if(*pt!=0xFFFF) return 0;  // not erased
    }
    return 1;} // erased

//  Program 1.6. Software that erases the MC68HC91B32 flash EEPROM.
#define tEPULSE 27500   // erase pulse 110000_s/4_s
#define tVERASE   250   // verify erase 1000_s/4_s
#define nEP 5           // maximum erase pulses
int EraseFlash(void){  // returns true if successful
unsigned int numErases=0; // number of erases attempted
int bErased=0;            // set to true when flash erased
    if(!(FEECTL&0x08)) return 0;   // SVFP return if no +12
    TSCR = 0x80;     // enable TCNT
    TMSK2= 0x35;     // 4_s clock
    FEECTL=0x06;     // ERAS and LAT
    *(int*)0x8000=0; // write anywhere to latch address
    while((!bErased)&&(numErases<nEP)){
      FEECTL=0x07;   // ERAS LAT and ENPE enable erase
      wait(tEPULSE); // wait 110 ms
      FEECTL=0x06;   // turn off ENPE 
      wait(tVERASE); // wait 1 ms
      numErases++;
      bErased=IsFlashErased();
    }
    if(bErased){     // if successful after numErases tries
       do{
         FEECTL=0x07;   // ERAS LAT and ENPE enable erase
         wait(tEPULSE); // wait 110 ms
         FEECTL=0x06;   // turn off ENPE 
         wait(tVERASE); // wait 1 ms
       } while (--numErases);
    }
    bErased=IsFlashErased();
    FEECTL=0x00;  // turn off
    return bErased;}

//  Program 1.7. Software that programs the MC68HC91B32 flash EEPROM.
#define tPPULSE 200   // program pulse 25us/125ns
#define tVPROG  80    // verify program 10us/125ns
#define nPP 50        // maximum program pulses
int ProgramFlash(volatile int *address, int data){ 
unsigned int numProg=0; // number of programs attempted
int bProg=0;            // set to true when flash programmed 
    if(!(FEECTL&0x08)) return 0;   // SVFP return if no +12
    TSCR = 0x80;  // enable TCNT
    TMSK2= 0x30;  // 125ns clock
    FEECTL=0x02;  // LAT
    *address=data; // address and data latched
    while((!bProg)&&(numProg<nPP)){
      FEECTL=0x03;   // LAT and ENPE enable erase
      wait(tPPULSE); // wait 25us
      FEECTL=0x02;   // turn off ENPE 
      wait(tVPROG);  // wait 10us
      numProg++;
      bProg=(*address==data);
    }
    if(bProg){     // if successful after numProg tries
       do{
          FEECTL=0x03;   // LAT and ENPE enable erase
          wait(tPPULSE); // wait 25us
          FEECTL=0x02;   // turn off ENPE 
          wait(tVPROG);  // wait 10us
       } while (--numProg);
    }
    bProg=(*address==data);
    FEECTL=0x00;  // turn off
    return bProg;} 

// Program 1.12. C definitions of some of the MC68HC812A4 I/O ports.
#define PORTA *(unsigned char volatile *)(0x0000)
//  General Purpose I/O Port
#define PORTB *(unsigned char volatile *)(0x0001)
//  General Purpose I/O Port
#define DDRA *(unsigned char volatile *)(0x0002)
//  Data Direction Register
#define DDRB *(unsigned char volatile *)(0x0003)
//  Data Direction Register
#define PORTC  *(unsigned char volatile *)(0x0004)
//  General Purpose I/O Port
#define PORTD  *(unsigned char volatile *)(0x0005)
//  General Purpose I/O Port
#define DDRC   *(unsigned char volatile *)(0x0006)
//  Data Direction Register
#define DDRD   *(unsigned char volatile *)(0x0007)
//  Data Direction Register
#define PORTE  *(unsigned char volatile *)(0x0008)
#define DDRE   *(unsigned char volatile *)(0x0009)
//  Data Direction Register
#define PORTH  *(unsigned char volatile *)(0x0024)
//  General Purpose I/O Port, Key wakeup, interrupt
#define DDRH   *(unsigned char volatile *)(0x0025)
//  Data Direction Register
#define PORTJ  *(unsigned char volatile *)(0x0028)
//  General Purpose I/O Port, Key wakeup, interrupt
#define DDRJ   *(unsigned char volatile *)(0x0029)
//  Data Direction Register
#define PORTF  *(unsigned char volatile *)(0x0030)
//  General Purpose I/O Port, Chip select logic
#define PORTG  *(unsigned char volatile *)(0x0031)
//  General Purpose I/O Port
#define DDRF   *(unsigned char volatile *)(0x0032)
//  Data Direction Register
#define DDRG   *(unsigned char volatile *)(0x0033)
//  Data Direction Register
#define PORTAD  *(unsigned char volatile *)(0x006F)
//  Analog input   General Purpose Input Port
#define TCNT *(unsigned short volatile *)(0x0084)
//   16-bit Timer
#define PORTT  *(unsigned char volatile *)(0x00AE)
//   Timer Input/Output Port General Purpose I/O Port
#define DDRT   *(unsigned char volatile *)(0x00AF)
//   Data Direction Register
#define SC0BD *(unsigned short volatile *)(0x00C0)
//   16-bit Baud rate Register
#define SC0CR1  *(unsigned char volatile *)(0x00C2)
//   Serial Port Control Register
#define SC0CR2  *(unsigned char volatile *)(0x00C3)
//   Serial Port Control Register
#define SC0SR1  *(unsigned char volatile *)(0x00C4)
//   Serial Port Status Register
#define SC0SR2  *(unsigned char volatile *)(0x00C5)
//   Serial Port Status Register
#define SC0DRH  *(unsigned char volatile *)(0x00C6)
//   high byte of Serial Port Data
#define SC0DRL  *(unsigned char volatile *)(0x00C7)
//   Serial Port Data Register
#define PORTS  *(unsigned char volatile *)(0x00D6)
//   Serial Input/Output Port General Purpose I/O port  
#define DDRS   *(unsigned char volatile *)(0x00D7)
//   Data Direction Register

// Program 1.15. C software that reads from port A and writes to port B.
// Program to implement a NOT gate
// Port A are the 8 digital inputs and Port B are the 8 digital outputs
// Software continuously repeats the following
// 1) Read value from Port A
// 2) Calculate the logical complement
// 3) Write the result out to Port B
#include "HC12.H"
void main(void){ unsigned char data;
  while(1){
    data = PORTA;   // Read from Port A 
    data = ~data;   // Logical complement
    PORTB = data;   // Write from to Port B
}}

// Program 1.17. C software that initializes an I/O port to input.
// MC68HC812A4 
    DDRJ=0x00;
// MC68HC912B32
    DDRA=0x00;

// Program 1.19. C software that reads from an I/O port input.
// MC68HC812A4
    Happiness=PORTJ;
//MC68HC912B32
    Happiness=PORTA;

// Program 1.21. C software that initializes an I/O port to output.
// MC68HC812A4
    DDRJ=0x0F;
// MC68HC912B32
    DDRA=0x0F;

// Program 1.23. C software that outputs an I/O port output.
// MC68HC812A4
    PORTJ=0xFF;
// MC68HC912B32
    PORTA=0xFF;

// Program 1.25. C functions that provide initialization, 
//        read and write access an I/O port.
// MC68HC812A4
void Init(unsigned char value){
    DDRJ=value;}
void Set(unsigned char value){
    PORTJ=value;}
unsigned char Read(void){
    return(PORTJ);}
// MC68HC912B32
void Init(unsigned char value){
    DDRA=value;}
void Set(unsigned char value){
    PORTA=value;}
unsigned char Read(void){
    return(PORTA);}

// Program 1.28. C programs that implement the 4 bit NOT gate.
// HC05C4, HC708XL36, HC11A8, HC812A4
void init(void){
    DDRC=0xF0;} // PC7-PC4 are outputs, PC3-PC0 are inputs
void main(void){ unsigned char data;
    init();     // call ritual once
    while(1){
       data=PORTC;      // input
       data=(~data)<<4; // complement and shift
       PORTC=data;}}    // output