chap13.c

Motorola 6808嵌入式接口设计开发原程序

// Chapter 13 6808 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

// Program 13.1. C implementation of a Traffic Light Controller.
/* Port B bits 5-0 outputs that control the traffic signal */
const struct State {
  unsigned char Out;         /* Output to Port B */
  unsigned short Time;       /* Time in sec to wait */
  const struct State *Next;  /* Next state */
};
typedef const struct State StateType;
#define NorthRed_EastGreen  &fsm[0]
#define NorthRed_EastYellow &fsm[1]
#define NorthGreen_EastRed  &fsm[2]
#define NorthYellow_EastRed &fsm[3]
StateType fsm[4]={
/* NorthRed_EastGreen, wait= 3 min, next state */
  {0x21, 180, NorthRed_EastYellow},  
/* NorthRed_EastYellow, wait= 15 sec, next state */
  {0x22, 15, NorthGreen_EastRed},  
/* NorthGreen_EastRed, wait= 3 min, next state */
  {0x0C, 180, NorthYellow_EastRed},   
/* NorthYellow_EastRed, wait= 15 sec, next state */
  {0x14, 15, NorthRed_EastGreen}};
void main(void){ StatePtr *Pt;  /* Current State */
  Pt=NorthRed_EastGreen; /* Initial State */
  DDRB=0xFF;             /* Make Port B outputs  */
  while(1){
    PORTB=Pt->Out;    /* Perform output for this state */
    Wait(Pt->Time);   /* Time to wait in this state */
    Pt=Pt->Next;      /* Move to next state */
  }
};

// Program 13.2 Circular list used to spin a stepper motor.
/* Port B bits 3-0 outputs that control the stepper motor */
const struct State {
  unsigned char Out;         /* Output to Port B */
  const struct State *Next;  /* Next state */
};
typedef const struct State StateType;
#define S6  &fsm[0]
#define S5  &fsm[1]
#define S9  &fsm[2]
#define S10 &fsm[3]
StateType fsm[4]={
  {0x06, S5},  
  {0x05, S9},  
  {0x09, S10},  
  {0x0A, S6};
StatePtr *Pt;  /* Current State */
unsigned short Speed;

// Program 13.3 C software to spin a stepper motor at a constant speed.
// MC68HC708XL36, Hiware compiler
interrupt 8 void TOC3handler(void){
   PORTB=Pt->Out; // output for this state 
   Pt=Pt->Next;   // Move to next state 
   TSC3&=0x7F;    // acknowledge CH3F
   TCH3=TCH3+Speed;} // Executed every step
void ritual(void) { 
asm{ sei};       // make atomic
  TSC=0x02;      // 500 ns clock
  TSC3=0x54;     // Arm output compare
  DDRB=0xFF;     // Make Port B outputs
  TSC3&=0x7F;    // Initially clear CH3F
  Speed=10000;   // initial speed
  Pt=S6;         // initial state
  TCH3=TCNT+2000; // First one in 1 ms
asm{ cli}; }

// Program 13.4 Port B is used to turn on the heater.
unsigned char Tlow,Thigh,T; int E;  // units in degrees C 
void Actuator(unsigned char relay){
  PORTB=relay;    // turns power on/off
}

// Program 13.5 Bang-bang temperature control software.
// MC68HC708XL36, Hiware compiler
interrupt 8 void TOC3handler(void){
   T=SE(); // estimated Temperature 
   E=Tstar-T;          // error
   if(T<Tlow) 
     Actuator(0);   // too cold->off
   else if (T>Thigh)
     Actuator(1);   // too hot->on
// leave as is if Tlow<T<Thigh 
   TSC3&=0x7F;    // acknowledge CH3F
   TCH3=TCH3+rate;} // periodic rate

// Program 13.6 Incremental position control software.
// MC68HC708XL36, Hiware compiler
interrupt 8 void TOC3handler(void){
int new;
   X=SE();  // estimated  position (mm)
   E=Xstar-X;     // error (mm)
   new=PORTB;     // promote to 16 bits
   if(E< -1)     new--; // decrease
   else if (E>1) new++; // increase
// leave as is if -1<E<1
   if(new<0)   new=0;    // underflow
   if(new>255) new=255;  // overflow
   PORTB=new;   // output to actuator
   TSC3&=0x7F;    // acknowledge CH3F
   TCH3=TCH3+rate;} // periodic rate