chap1.c

摩托罗拉Mc6805利程

// Chapter 1 6805 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

// Program 1.17. C software that initializes an I/O port to input.
// MC68HC705J1A
    DDRA=0x00;

// Program 1.19. C software that reads from an I/O port input.
// MC68HC705J1A
    Happiness=PORTA;

// Program 1.21. C software that initializes an I/O port to output.
// MC68HC705J1A
    DDRA=0x0F;

// Program 1.23. C software that outputs an I/O port output.
// MC68HC705J1A
    PORTA=0xFF;

// Program 1.25. C functions that provide initialization, 
//        read and write access an I/O port.
// MC68HC705J1A
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