Cours:TP printempsM4209 TP 4 Corr

Exercice 2

On a gardé le chenillar de l'exercice 1 et ajouté le compteur BCD :

#include "avr/io.h"
#undef F_CPU 
#define F_CPU 15000000UL
#include "util/delay.h"

void incrementBCD(unsigned char *cnt) { 
  (*cnt)++;    
  if ((*cnt & 0x0F) > 0x09) *cnt += 6; 
  if ((*cnt & 0xF0) > 0x90) *cnt = 0; 
} 
 
void decrementBCD(unsigned char *cnt) { 
  (*cnt)--;    
  if ((*cnt & 0x0F) == 0x0F) *cnt -= 6; 
  if ((*cnt & 0xF0) == 0xF0) *cnt = 0x99; 
}



//***********************************************************************
// main 
//*********************************************************************** 

 int main (void) {
   unsigned char ch=128, cmpt = 0;
   const unsigned char digit7segs[16]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x88,0x83,0xC6,0xA1,0x86,0x8E}; 
   while(1) { 
   // echo simple
     PORTA = ch;
     ch >>= 1; 
     if (ch == 0) ch = 128;
     if (PINA & 0x01) decrementBCD(&cmpt); else incrementBCD(&cmpt);
     PORTB = digit7segs[cmpt & 0x0F];
     DDRB = digit7segs[(cmpt>>4) & 0x0F];
     _delay_ms(1000); // on verra passer les caractères     
   } 
   return 0; 
 }