;******************************************************************
;
;  //  setup a 1000 usec PWM period with PR2 = 249 and prescaler
;  //  4:1 (4 MHz clock) for 20 PWM 'frames' per 20 msec Servo
;  //  period and 1 usec pulse width resolution
;
;  int servo = 1500;              // pulse width in 1 usec ticks
;  int pulse = 0;                 // ISR work variable
;  int frame = 1;                 // frame number 1..20
;
;  void ISR()
;  { PIR1bits.TMR2IF = 0;         // clear Timer 2 interrupt flag
;    if (--frame == 0)            // if end of the 20 msec period
;    { frame = 20;                // reset for new 20 msec period
;      pulse = servo;             // reset 'pulse' work variable
;    }
;    if ((pulse > 1000)           // if pulse > 1000 usecs
;    { CCPR1L = 250;              // do a 100% duty cycle frame
;      CCP1CONbits.CCP1Y = 0;     //
;      CCP1CONbits.CCP1X = 0;     //
;      pulse -= 1000;             // subtract 1000 usecs
;    }
;    else
;    { CCP1CONbits.CCP1Y = (pulse & 1);
;      CCP1CONbits.CCP1X = (pulse & 2);
;      CCPR1L = (pulse >> 2);     // 0..249 (0..999 usecs)
;      pulse = 0;                 // remaining frames are 0%
;    }
;  }