isem.ino

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#include <krnl.h>
 
// External triggered ISR
// An Interrupt Service Routine is attached to pin 2
// So when pin2 is drived to ground (by a wire) an interrupt is generated.
// The ISR increment a counter and send it to a message Q
// naming ki_send .... "i" indicates it can be used in an ISR and demand interrupt to be disabled prio to call
// and that no task shift takes place in the call
// demonstrates ISR with  message Q and preemption(task shift) in the ISR
// NB Take a look on the ISR. For 1280 and 2560 it is INT4 but for 168,328,.. it's INTO
// It is taken care by a compile flag
// (c) beerware license JDN 2013
// AS USUAL Serial.print is not krnl safe !!! cant break your program
 
struct k_t * p_t1, *sem1;
 
#define STK_SIZE 400
 
char s1[STK_SIZE]; // stak for t1 ... and t2
 
 
volatile int icnt=0;
 
void doBlink(void) {
  static char flag = 0;
  flag = ! flag;
  digitalWrite(13,flag);
}
 
 
 
void t1(void) {
 
  while (1) {
  int i;
 
    k_wait(sem1,0); // wait forever
    doBlink();
  }
 
}
 
 
#if defined (__AVR_ATmega2560__) || defined (__AVR_ATmega1280__)
ISR(INT4_vect,ISR_NAKED) {
#else
ISR(INT0_vect, ISR_NAKED) {
#endif
 
  // no local vars ?!?  ! I think
  PUSHREGS();
  if (!k_running)
    goto exitt ;
 
  icnt++;   
  ki_signal(sem1); 
  K_CHG_STAK();
exitt:
 
  POPREGS();
  RETI();
}
 
void initISR()
{
  DI();
  pinMode(2,INPUT);  // set som input
  digitalWrite(2,HIGH);  // enable pullup resistor
#if defined (__AVR_ATmega2560__) || defined (__AVR_ATmega1280__)
  // 1280/2560 mega pin2 intr:4, pin5 intr:5
  EIMSK |= (1 << INT4);  // enable external intr
  EICRB |= (1 << ISC41); // trigger INT4 on falling edge
#else
  EIMSK |= (1 << INT0);  // enable external intr
  EICRA |= (1 << ISC01); // trigger INT0 on falling edge
#endif
 
  EI();
}
 
void setup() {
 
  Serial.begin(9600);
  pinMode(13,OUTPUT);
 
  k_init(1,1,0); // from now you can crt task,sem etc
 
  sem1 = k_crt_sem(0,10); // 
 
  p_t1 = k_crt_task(t1, 10, s1, STK_SIZE);
   
  initISR();
 
  Serial.println("just bef");
  k_start(10); // now we are runnning   with timer 10 msev
  //Serial.println("oev");
 
  // main will not come back and will sleep rest of life
}
 
void loop(void) {
  // just for compilation - will never be called
}
 
/* QED :-) */