chap8.c

摩托罗拉Mc6805利程

// Chapter 8 6805 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

// Program 8.1. The MC68HC812A4 Port J initialization.
// MC68HC812A4 only


// Program 8.18. Helper function for a simple LCD display.
void LCDOutDigit(unsigned char position, unsigned char data) { 
// position is 0x80, 0x40, 0x20, or 0x10  and data is the BCD digit
	PORTB=0x0F&data;  // set BCD digit on the A-D inputs of the MC14543B
	PORTB|=position;  // toggle one of the LD inputs high 
	PORTB=0x0F&data;} // LD=0, latch digit into MC14543B


// Program 8.19. C software interface of a simple LCD display.
void LCDOutNum(unsigned int data){ unsigned int digit,num,i; 
unsigned char pos;
      num=min(data,9999); // data should be unsigned from 0 to 9999
      pos=0x10;   // position of first digit (ones)
      for(i=0;i<4;i++){
          digit=num%10; num=num/10; // next BCD digit 0 to 9
          LCDOutDigit(pos,digit); pos=pos<<1;}}

// Program 8.20. Bit-banged interface to a scanned LCD display.
void LCDOut (unsigned char *pt) {unsigned int i;  unsigned char mask; 
    for(i=0;i<6;i++){  
       for(mask=0x80;mask;mask=mask>>1){  // look at bits 7,6,5,4,3,2,1,0
          if((*pt)&mask) PORTB=1; else PORTB=0; // Serial data of the MC145000
	    PORTB|=2;      // toggle the serial clock first high 
	    PORTB&=0xFD;}  // then low
       pt++; }}


// Program 8.27. C linked list and helper functions used to control the stepper motor.
const struct State
{   unsigned char Out;     /* Output for this state */
    const struct State *Next[2]; /* Next state CW or CCW motion */
};
#typedef struct State StateType;
#typedef StateType * StatePtr;
unsigned char POS;  /* between 0 and 199 representing shaft angle */
#define clockwise 0           /* Next index*/
#define counterclockwise 1    /* Next index*/
StateType fsm[4]={
    {10,{&fsm[1],&fsm[3]}},
    { 9,{&fsm[2],&fsm[0]}},
    { 5,{&fsm[3],&fsm[1]}},
    { 6,{&fsm[0],&fsm[2]}}
};
StatePtr Pt;  /* Current State */
void CW(void){
     Pt=Pt->Next[clockwise];    /* circulates around linked list */
    PORTB=Pt->Out;              /* step motor */
    if(POS++==200) POS=0;}       /* maintain shaft angle */ 
void CCW(void){
    Pt=Pt->Next[counterclockwise]; /* circulates around linked list*/
    PORTB=Pt->Out;                 /* step motor */
    if(POS==0)POS=199;
    else POS--; }               /* maintain shaft angle */
void Init(void){
    POS=0;
    DDRB=0xFF;
    Pt=&fsm[0];}

// Program 8.28. High-level C function to control the stepper motor.
void SEEK(unsigned char New){ int CWsteps,i; 
    if((CWsteps=New-POS)<0) 
       CWsteps+=200;
    if(CWsteps>100) 
       for(i=CWsteps;i<200;i++) 
          CCW();
    else 
       for(i=0;i<CWsteps;i++)
          CW(); }