chap15.c

Motorola 6812芯片开发的接口程序。

// Chapter 15 6812 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

//  Program 15.1. Real time data acquisition with a simple digital filter, Equation 2.
// MC68HC812A4
#define Rate 2000
#define OC5  0x20
#pragma interrupt_handler TOC5handler()
void TOC5handler(void){
   TFLG1=OC5;       // ack OC5F
   TC5=TC5+Rate;    // Executed every 1 ms
   x[1]=x[0];       // shift MACQ data
   x[0] = A2D(channel);  // new data
   y=(x[0]+x[1])>>1;}

void ritual(void) { 
asm(" sei");     // make atomic
  TIOS|=OC5;     // enable OC5
  TSCR|=0x80;    // enable
  TMSK2=0x32;    // 500 ns clock
  TMSK1|=OC5;    // Arm output compare 5
  x[0] = x[1] = 0;
  TFLG1=OC5;     // Initially clear C5F
  TC5=TCNT+Rate; // First one in 1 ms
asm(" cli"); }

//  Program 15.2. Real time data acquisition with a simple digital filter, Equation 3.
// MC68HC812A4
#define OC5  0x20 
#pragma interrupt_handler TOC5handler()
void TOC5handler(void){ unsigned int i;
   TFLG1=OC5;       // ack OC5F
   TC5=TC5+5556;    // fs=360Hz
   for(i=5;i>0;i++) 
       x[i]=x[i-1];      // shift MACQ data
   x[0] = A2D(channel);  // new data
   y=(x[0]+x[1]+x[2]+x[3]+x[4]+x[5])/6;}
void ritual(void) { 
asm(" sei");     // make atomic
  TIOS|=OC5;     // enable OC5
  TSCR|=0x80;    // enable
  TMSK2=0x32;    // 500 ns clock
  TMSK1|=OC5;    // Arm output compare 5
  x[0]=x[1]=x[2]=x[3]=x[4]=x[5]=0;
  TFLG1=OC5;     // Initially clear C5F
  TC5=TCNT+5556; 
asm(" cli"); } 

//  Program 15.3. Real time data acquisition with a simple digital filter, Equation 4.
// MC68HC812A4
#define OC5  0x20 
#pragma interrupt_handler TOC5handler()
void TOC5handler(void){ 
   TFLG1=OC5;       // ack OC5F
   TC5=TC5+5556;    // fs=360Hz
   x[3]=x[2];       // shift MACQ data
   x[2]=x[1];
   x[1]=x[0];   
   x[0] = A2D(channel);  // new data
   y=(x[0]+x[3])>>1;}     
void ritual(void) { 
asm(" sei");     // make atomic
  TIOS|=OC5;     // enable OC5
  TSCR|=0x80;    // enable
  TMSK2=0x32;    // 500 ns clock
  TMSK1|=OC5;    // Arm output compare 5
  x[0]=x[1]=x[2]=x[3]=0;
  TFLG1=OC5;     // Initially clear C5F
  TC5=TCNT+5556; 
asm(" cli"); } 

 // Program 15.4. Compiler listings for the filter implementation.
; MC68HC812A4, ICC12
; y=(x[0]+x[3])>>1;
  ldab _x+3  ; 8-bit x[3]
  clra       ; promote into RegD
  std -10,x  ; save on stack
  ldab _x    ; 8 bit x[0]
  clra       ; promote into RegD
  addd -10,x ; 16-bit x[0]+x[3]
  asra
  rolb       ; 16-bit shift
  stab _y    ; demote to 8 bit  

//   Program 15.5. Real time data acquisition with a simple digital filter, Equation 5.
// MC68HC812A4
#define Rate 2000
#define OC5  0x20
#pragma interrupt_handler TOC5handler()
void TOC5handler(void){
   TFLG1=OC5;       // ack OC5F
   TC5=TC5+Rate;    // Executed at fs
   y[1]=y[0];       // shift MACQ data
   x = A2D(channel);  // new data
   y[0]=(x+y[1])>>1;} // 16-bit

void ritual(void) { 
asm(" sei");     // make atomic
  TIOS|=OC5;     // enable OC5
  TSCR|=0x80;    // enable
  TMSK2=0x32;    // 500 ns clock
  TMSK1|=OC5;    // Arm output compare 5
  y[0] = y[1] = 0;
  TFLG1=OC5;     // Initially clear C5F
  TC5=TCNT+Rate; // First one in 1 ms
asm(" cli"); } 

// Program 15.6: The median filter is an example of a nonlinear filter.
unsigned char Median(unsigned char u1,unsigned char u2,unsigned char u3){ 
unsigned char result;
  if(u1>u2)
    if(u2>u3)   result=u2;     // u1>u2,u2>u3       u1>u2>u3
      else
        if(u1>u3) result=u3;   // u1>u2,u3>u2,u1>u3 u1>u3>u2
        else      result=u1;   // u1>u2,u3>u2,u3>u1 u3>u1>u2
  else 
    if(u3>u2)   result=u2;     // u2>u1,u3>u2       u3>u2>u1
      else
        if(u1>u3) result=u3;   // u2>u1,u2>u3,u1>u3 u2>u1>u3
        else      result=u1;   // u2>u1,u2>u3,u3>u1 u2>u3>u1
  return(result):}
unsigned char x[3],y;   
// x[0] is x(n) the current sample
// x[1] is x(n-1) the sample 1/fs ago
// x[2] is x(n-2) the sample 2/fs ago
void sample(void){
   x[2]=x[1];  // shift MACQ data
   x[1]=x[0];   
   x[0] = A2D(0);  // new data from channel 0
   y=median(x[0],x[1],x[2]); 

//    Program 15.7. Real time data acquisition with a 60 Hz notch digital filter, Equation 58.
// MC68HC812A4
#define OC5  0x20 
#pragma interrupt_handler TOC5handler()
void TOC5handler(void){ 
   TFLG1=OC5;       // ack OC5F
   TC5=TC5+8333;    // fs=240Hz
   y[2]=y[1]; y[1]=y[0];  // shift MACQ
   x[2]=x[1]; x[1]=x[0];   
   x[0] = A2D(channel);  // new data
   y[0]=(113*(x[0]+x[2])-98*y[2])>>7;}     

void ritual(void) { 
asm(" sei");     // make atomic
  TIOS|=OC5;     // enable OC5
  TSCR|=0x80;    // enable
  TMSK2=0x32;    // 500 ns clock
  TMSK1|=OC5;    // Arm output compare 5
  y[0]=y[1]=y[2]=x[0]=x[1]=x[2]=0;
  TFLG1=OC5;     // Initially clear C5F
  TC5=TCNT+8333; 
asm(" cli"); }