void __attribute__((interrupt, no_auto_psv)) _T1Interrupt (void)
{
IFS0bits.T1IF = 0;
Period = ActualCapture - PastCapture; // This is an UNsigned substraction
// to get the Period between one
// hall effect sensor transition
// These operations limit the Period value to a range from 60 to 6000 rpm
[B] if (Period < (unsigned int)MINPERIOD) // MINPERIOD or 6000 rpm
Period = MINPERIOD;
else if (Period > (unsigned int)MAXPERIOD) // MAXPERIOD or 60 rpm
Period = MAXPERIOD;
// PhaseInc is a value added to the Phase variable to generate the sine
// voltages. 1 electrical degree corresponds to a PhaseInc value of 184,
// since the pointer to the sine table is a 16bit value, where 360 Elec
// Degrees represents 65535 in the pointer.
// __builtin_divud(Long Value, Int Value) is a function of the compiler
// to do Long over Integer divisions.
PhaseInc = __builtin_divud(512000UL, Period); // Phase increment is used
// by the PWM isr (SVM)
[/B]
// This subroutine in assembly calculates the MeasuredSpeed using
// fractional division. These operations in assembly perform the following
// formula:
// MINPERIOD (in fractional)
// MeasuredSpeed = ---------------------------
// Period (in fractional)
//
__asm__ volatile("repeat #17\n\t"
"divf %1,%2\n\t"
"mov w0,%0" : /* output */ "=g"(MeasuredSpeed)
: /* input */ "r"(_MINPERIOD),
"e"(Period)
: /* clobber */ "w0");
// MeasuredSpeed sign adjustment based on current motor direction of
// rotation
if (Current_Direction == CCW)
MeasuredSpeed = -MeasuredSpeed;
// The following values represent the MeasuredSpeed values from the
// previous operations:
//
// CONDITION RPM SFRAC16 SINT HEX
// Max Speed CW -> 6000 RPM -> 0.996805 -> 32663 -> 0x7F97
// Min Speed CW -> 60 RPM -> 0.009984 -> 327 -> 0x0147
// Min Speed CCW -> -60 RPM -> -0.009984 -> -327 -> 0xFEB9
// Max Speed CCW -> -6000 RPM -> -0.996805 -> -32663 -> 0x8069
SpeedControl(); // Speed PID controller is called here. It will use
// MeasuredSpeed, RefSpeed, some buffers and will generate
// the new ControlOutput, which represents a new amplitude
// of the sinewave that will be generated by the SVM
// subroutine.
#ifdef PHASE_ADVANCE
// Calculate Phase Advance Based on Actual Speed and MAX_PH_ADV define
// The following assembly instruction perform the following formula
// using fractional multiplication:
//
// PhaseAdvance = MAX_PH_ADV * MeasuredSpeed
//
register int a_reg asm("A");
a_reg = __builtin_mpy(_MAX_PH_ADV, MeasuredSpeed, 0,0,0,0,0,0);
PhaseAdvance = __builtin_sac(a_reg,0);
#endif
MotorStalledCounter++; // We increment a timeout variable to see if the
// motor is too slow (not generating hall effect
// sensors interrupts frequently enough) or if
// the motor is stalled. This variable is cleared
// in halls ISRs
if ((MotorStalledCounter % _10MILLISEC) == 0)
{
ForceCommutation(); // Force Commutation if no hall sensor changes
// have occured in specified timeout.
}
else if (MotorStalledCounter >= _100MILLISEC)
{
StopMotor(); // Stop motor is no hall changes have occured in
// specified timeout
}
return;
}