AVR-Chat

Hello

I using a Mega48, coded in ASM. I have debounced switches on PD2 (INT0) and
PD3 (INT1).

In my code, I'm enabling both INT1 and INT0 on a rising edge, and enabling
the global int flag, using something like this:

I have the pins and ports defined in a separate inc file

.cseg
.org 0x00
	rjmp RESET
	rjmp EXT_INT0
	rjmp EXT_INT1
      rjmp ERR_01				// PCINT0 ; PCINT0 Handler
// .... rest of isr vectors all point to same address as above


RESET:
INITIALIZE_AVR:
	ldi temp, high(RAMEND)
	out SPH, temp
	ldi temp, low(RAMEND)
	out SPL, temp

	// set pins for stepper/5804 as outputs
	sbi StepDDR, EnablePin
	sbi StepDDR, DirPin
	sbi StepDDR, StepPin

	// set the err LED pin as output
	sbi ErrDDR, ErrPin

	cbi SwitchDDR, E_SwPin
	cbi SwitchDDR, FootSwPin
	cbi SwitchDDR, SensorPin

	// set default values for pins
	StepDown  // these are macros
	StepLow
	EnableOff
	ErrPinOff

	// set up ext ints 0 & 1
	// EICRA has the bits to set the levels of the ints
	// we want both INT0 & INT1 to trigger on the rising edge
	// for INT0, rising edge, ISC01,ISC00 = 11
	// for INT1, rising edge, ISC11_ISC10 = 11
	ldi temp, 0b00001111
	sts EICRA, temp
	// enable INT0 & INT1 => EIMSK - INT0=bit 0, INT1=bit 1
	ldi temp, 0b00000011
	out EIMSK, temp
	sei
// end INIT


MAIN:		// inf loop
	NOP
	rjmp MAIN

EXT_INT1:
	// control stepper in here - up/ down stroke
	//
	// at end of this routine I set the INT1 flag  - this way,
	// even if the button was accidently pressed twice, it will
	// only execute one stroke at a time, and ignores any more
	// button presses until the ISR is completed
	sbi EIFR, INT1
// end EXT_INT1


EXT_INT0:
	// emergency sw was pressed
	// blink the emrgency LED
// end EXT_INT0


 -- now my question is, how can I get the INT0 switch to IMMEDIATELY
interrupt any code that is running, and go to the EXT_INT0 label and begin
execution the code there? Right now, what's happening is the INT0 waits
until the INT1 routine returns back to MAIN before it jumps to the ISR,
which could be too late....

Randy