F) Pulse Accumulator Overflow Triggered Interrupt - Motorola 68HC12 User Manual

Pulse Accumulator Overflow Triggered Interrupt:
Operation
This operation triggers an interrupt every time the pulse accumulator overflows.
Whenever the pulse accumulator overflows from 0xFFFF to 0x0000, the ISR will
trigger. The set up of this interrupt is very similar to the edge triggered
interrupt, although PAMOD and PAEDGE
other settings are the same as for the edge triggered operation of the Pulse
Accumulator. However instead of setting PAI to one, for Overflow operation PAOVI
is set to one.
The user must clear the flag in the ISR by writing a 1 to PAOVIF in the _H12PAFLG
register.
_H12PACTL:
bit 7 bit 6
unused PAEN
_H12PAFLG:
bit 7 bit 6
unused unused
Sample Code
This code simply displays when the interrupt is triggered.
_ _mod2_ _ void PAOvfInt();
void _ _main()
{
DB12->SetUserVector(PAOvf, PAOvfInt);
_H12PACTL=0x46;
while(1)
{
}
}
_ _mod2_ _ void PAOvfInt()
{
DB12->printf("triggered");
_H12PAFLG=0x02;
}
bit 5 bit 4
PAMOD PEDGE
bit 5 bit 4
Unused unused
// function prototype
// set for pulse accumulator overflow
// wait
// Pulse Accumulator ISR
// clear the flag
have no effect on the interrupt.
bit 3 bit 2
CLK1 CLK0
bit 3 bit 2
unused unused
22
bit 1 bit 0
PAOVI PAI
bit 1 bit 0
PAOVIF PAIF
Most of the