calling subroutine triggers interrupt

[Alexey]

Hi Mister_E,

Unfortunately this does not help. I removed all irrelevant code from the program to make it more clear, sorry for not doing this before. The code I have now for test is below. When it starts, calling empty Test subroutine always triggers interrupt so the GREENLED is ON. If I disable the GOSUB TEST, then it starts with GREENLED OFF (interrupt handler did not run)

This is the first time I play with interrupt - most likely do something wrong. The MCU is PIC16F688

@ DEVICE pic16F688, WDT_OFF, INTOSCIO, PWRT_ON, MCLR_ON, BOD_OFF

define OSC 4
clear
'---------INTERRUPTS CONFIG-----------
INTCON = %10000 'ENABLES RA2 (1,) OTHER INTERRUPTS ON PORTA ARE OFF (BIT 3)
IOCA = %100 'ENABLES INTERRUPT ON PORTA.2
;---------VARIABLES----------------------

BTN VAR PORTA.2
YW VAR PORTC.2
REDLED VAR PORTC.4
GREENLED VAR PORTC.5
N VAR BYTE


'-----------PORTS CONFIGURATION------------
OPTION_REG = 0
ANSEL = %1000 'PORTA4/AN3 IS ANALOG
TRISA = %111100 'SET PORT A FOR OUTPUTS ON PINS 0,1 (UNUSED) ALL OTHER INPUTS
TRISC = %000010 'SET PORT C FOR INPUT ON PIN 1 (DIAG IN) ALL OTHER OUTPUTS
'THE FOLLOWING DID NOT HELP
N=PORTA 'JUST TO READ PORTA
INTCON.0=0 'CLEAR INTERRUPT FLAG AFTER READING PORT (RAIF FLAG)
INTCON.1=0 'CLEAR INTF FLAG FOR PORT RA2
PORTC=0 'GREENLED SHOULD STAY OFF

GOSUB TEST 'THIS SUBROUTINE ALWAYS CAUSES INTERRUPT!!!
'NOW GREENLED ON PORT C5 IS ON !!!



'THE FOLLOWING DID NOT HELP
N = PORTA 'READ PORT A TO CLEAR MISMUTCH, NOTHING ELSE
INTCON.0=0 'CLEAR INTERRUPT FLAG AFTER READING PORT
INTCON.1=0

ON INTERRUPT GOTO BTN_CHECK ' CHECK ON/OFF BUTTON

START:
GOTO START 'WAIT HERE TILL INTERRUPTED


TEST: 'NO CODE IN THIS SUBROUTINE

RETURN

DISABLE
BTN_CHECK:
IF GREENLED = 0 THEN
GREENLED = 1
ELSE
PORTC=0
ENDIF
'' PAUSE 1000 'ANTI VIBRATION
N = PORTA 'READ PORT A TO CLEAR MISMUTCH, NOTHING ELSE
INTCON.0=0 'CLEAR INTERRUPT FLAG AFTER READING PORT (RAIF FLAG)
INTCON.1 = 0 'CLEAR INTF FLAG FOR PORT RA2
RESUME
ENABLE

[Darrel Taylor]

I think Steve meant to clear the flag before the GOSUB TEST, not before the ON INTERRUPT GOTO.

It GOSUB's from an area that is DISABLEd to one that is ENABLED.
If the flag is set, it will jump to the ISR.
It may jump, even if it's not set.

The ISR should verify that the flag is set before doing anything.

[Bruce]

Without INTCON.7 set before ON INTERRUPT, it's going to jump to your interrupt vector all the time in any code section where interrupt code is inserted. If you just set INTCON.7 it should never jump there until the hardware interrupt clears INTCON.7 automatically.

INTCON = %10000 doesn't set INTCON.7 - so the ON INTERRUPT code inserted always assumes an interrupt condition exists.

[Alexey]

Darrel, Bruce,

Thank you!

I tried to move "On interrupt goto" to the very top and also check flag in the interrupt handler, either one works just fine.

Will play with INTCON.7 tomorrow morning.

Thanks again, the problem seems to be solved

Alexey