16F1827 ASM Interrupt

I am using a 16F1827 I need to use the ASM style interrupt routine to free up some program space. There are two pins that will fire if they go high. Either fires the interrupt properly, the existing output can be turned low properly but for some reason changing the input to an output and making it high is not functioning and the LED flashing routine doesn't change based on the interrupt as it should. I am sure I am missing something simple but I just can't seem to figure it out...

The interrupt is very simple, all I am needing to do is:
Change an input to an output

Make the new output high

Make an existing output low

Determine which one of two interrupts got tripped and goto a LED flashing routine for user feedback

Continue in an endless loop flashing the indication LED

Code:

'setup the interrupts DEFINE INTHAND intRoutine 'where to go when an interrupt fires IOCBP = %00001100 INTCON = %10011000 ' Enable interrupt ;the following is the interrupt routine ASM intRoutine ;turn off interrupts MOVLW b'00000000' MOVWF INTCON ;disable all interrupts that were previously enabled MOVLW b'00000000' MOVWF IOCBP ;RB3 is currently an input, change it to an output and make it high ;prior to this operation TRISB would be 11111110 MOVLW b'11110110' MOVWF TRISB ;turn on RB3 (doesn't go high) BSF PORTB,3 ;turn off detection power (this is working fine) BCF PORTA,0 ;check to see what tripped the interrupt ;(this always goes to detectionFlash even when lighting activated the interrupt) ;IOCBF.2 = detection ;IOCBF.3 = lighting BTFSS IOCBF,3 GOTO detectionFlash GOTO lightingFlash lightingFlash BSF _overCurrentLED CALL Delay BCF _overCurrentLED CALL Delay CALL Delay GOTO lightingFlash detectionFlash BSF _overCurrentLED CALL Delay BCF _overCurrentLED CALL Delay BSF _overCurrentLED CALL Delay BCF _overCurrentLED CALL Delay CALL Delay GOTO detectionFlash endASM

Re: 16F1827 ASM Interrupt

When it gets to the ISR, it could be in any bank at the time.
INTCON is available from any bank, but ...

PORTB is in BANK0.
TRISB is in BANK1.
IOCBF is in BANK7.

Use BSR to change banks.

Re: 16F1827 ASM Interrupt

Could also use BANKSEL reg_name

For instance:

Code:

BANKSEL TRISB bla bla bla BANKSEL IOCBF bla bla bla

works just like BSR but no need to lookup the bank number.

Re: 16F1827 ASM Interrupt

Thanks Darrel that clears up why things were not working as I expected!

Most things are working great now except one very strange thing. The LED that is to be used to indicate this interrupt state (on RB0) works fine when RB3 has initiated the interrupt however when RB2 has initiated the interrupt when I attempt to flash RB0 it somehow turns off RB2 which is the pin that was changed from an input to an output and made high.

In the code shown below I am using the wrong LED (RA6) to indicate the RB2 interrupt condition and everything works fine other than the wrong LED flashing.

I am thinking that there is some strange property that RB0 has but I am very confused why it doesn't mess up when RB3 has initiated the interrupt.

Code:

;the following is the interrupt routine ASM intRoutine ;turn off interrupts MOVLW b'00000000' MOVWF INTCON ;disable all interrupts that were previously enabled MOVLB 0x07 ;select BANK 7 MOVLW b'00000000' MOVWF IOCBP ;RB3 is currently an input, change it to an output and make it high ;prior to this operation TRISB would be 11111110 MOVLB 0x01 ;select BANK 1 MOVLW b'11110110' MOVWF TRISB ;turn on RB3 (doesn't go high) MOVLB 0x00 ;select BANK 0 BSF PORTB,3 ;turn off detection power (this is working fine) BCF PORTA,0 ;check to see what tripped the interrupt ;IOCBF.2 = detection ;IOCBF.3 = lighting MOVLB 0x07 ;select BANK 7 BTFSS IOCBF,3 GOTO detectionFlash GOTO lightingFlash lightingFlash MOVLB 0x00 ;select BANK 0 BSF PORTB,0 CALL Delay BCF PORTB,0 CALL Delay CALL Delay GOTO lightingFlash detectionFlash MOVLB 0x00 ;select BANK 0 BSF PORTA,6 ;this is the wrong LED but works properly when this one is selected instead of PORTB,0 CALL Delay BCF PORTA,6 CALL Delay BSF PORTA,6 CALL Delay BCF PORTA,6 CALL Delay CALL Delay GOTO detectionFlash endASM

Re: 16F1827 ASM Interrupt

Thanks for the code example cncmachineguy.

I have it working properly now. I am thinking there must be some type of race condition with the way I had it coded. I have added a delay right after B3 was made high and everything works fine. Without the delay B3 goes low as soon as B0 is made high.

Thanks for the help guys!