Computertechnik mit Mikrocontrollern

KAPITEL 13. AUFBAU DES SYSTEMS 193
#include
// parameter for Timer0
unsigned short prescaler[6]={ 0,1,8,64,256,1024 };
unsigned char psindex = 5;
unsigned char tim0cnt = 144; // => 25 Hz
#include "mainboard.h"
#include "putbyte_disp.c"
void displa (unsigned long i2)
{
if (i2>=10) displa (i2/10);
putbyte (i2%10+’0’);
}
void display()
{
putbyte (’\f’);
displa (Clock);
putbyte (’H’); putbyte (’z’);
putbyte (’/’); putbyte (’2’); putbyte (’/’);
putbyte (’\r’); putbyte (’\n’);
displa (prescaler[psindex]);
putbyte (’/’);
displa (tim0cnt);
putbyte (’=’);
displa (Clock/2/prescaler[psindex]/tim0cnt);
putbyte (’H’); putbyte (’z’);
}
unsigned char taster (unsigned char n)
{
static unsigned char state [4];
switch (n) {
case 1: if(!state[0] && bit_is_clear(tas1_PIN,tas1_PB)) return state[0]=1;
else if (bit_is_set(tas1_PIN,tas1_PB)) state[0]=0; return 0;
case 2: if(!state[1] && bit_is_clear(tas2_PIN,tas2_PB)) return state[1]=1;
else if (bit_is_set(tas2_PIN,tas2_PB)) state[1]=0; return 0;
case 3: if(!state[2] && bit_is_clear(tas3_PIN,tas3_PB)) return state[2]=1;
else if (bit_is_set(tas3_PIN,tas3_PB)) state[2]=0; return 0;
case 4: if(!state[3] && bit_is_clear(tas4_PIN,tas4_PB)) return state[3]=1;
else if (bit_is_set(tas4_PIN,tas4_PB)) state[3]=0; return 0;
}
}
ISR ( SIG_OVERFLOW0 ) // timer0
{
static unsigned char buzzer;
sei();
TCNT0 = ~tim0cnt;
if (buzzer) {sbi(buzzer_PORT,buzzer_PB);buzzer=0;}
else {cbi(buzzer_PORT,buzzer_PB);buzzer=1;}
}
main ()
{
TCCR0B = psindex;
TCNT0 = ~tim0cnt;
sbi (TIMSK0,TOIE0);