Listing 1a—Here’s the main routine for ETS. You program the timer using EtsSetTimerperiod() and install the servo interrupt service routine (ISR) as a timer call back using EtsRegisterCallback() from the ETS application programming interface. b—In QNX, setting up the ISR is done much like in ETS. clock_setres() sets the timer period, and qnx_hint_attach() attaches an ISR to the timer call-back chain. Since QNX is an operating system, which persists after we get done running our program, we want to make sure that we remove our ISR when done.

a)

#include "global.h"
#include "servo.h"
main() {
  int Servo_Isr();
  EtsSetTimerPeriod(1);
  EtsRegisterCallback((WORD)ETS_CB_TIMER,
    &Servo_Isr, 0, ETS_CB_ADD);
  GaitThread(); }

b)

#include "global.h"
#include "servo.h"
main(){
  pid_t far Servo_Isr();
  int id,i;
  struct timespec st;
  st.tv_sec = 0;
  st.tv_nsec = 500000;
  clock_setres(CLOCK_REALTIME, &st);
  if((id = qnx_hint_attach( 0, &Servo_Isr,
      FP_SEG(&SetTime[0]))) == -1 ){
    printf("can't attach interrupt\n");
    exit(2); }
  GaitThread();
  qnx_hint_detach(id); }