what's wrong with this interrupt

[micro]

the prog. below is a simple interrupt enables RB7 to RB4 ports to work as external interrupt, i used one of them to view numbers countes from 0 to 5 and display it on serial LCD and return to a main prog. to view a message, but the problem when i enter intterupt i can not get out from it, i did the same prgo to RB0 and gave me good result, but with RB7-RB4 is not



trisa=%00000
trisb=%11111111

option_reg=%10000000
intcon = %10001000
I var byte

on interrupt goto int

main:

serout porta.0,2,[254,1]
pause 10
serout porta.0,2,["Hello"]
pause 100
goto main

disable interrupt

int:

for i=0 to 5

serout porta.0,2,[254,1]
pause 10
serout porta.0,2,[#i]
pause 1000

next i

INTCON.0=0

resume
enable interrupt
end

[mister_e]

pic model ?

[micro]

pic16f84
sorry i forgot that

[Bruce]

Read portB on entry into the interrupt routine to end the mismatch condition.

SomeVar = PORTB ' read portB

Then clear the interrupt flag before exiting your interrupt routine.

INTCON.0 = 0 ' RB port change int flag is cleared.

Now whenever portB is different from the last value read, INTCON.0 will be set, and you'll vector back to your interrupt routine.

Read this app note for more details:
http://ww1.microchip.com/downloads/en/AppNotes/00566b.pdf

[micro]

i solved the problem with another method as below


trisa=%00000
trisb=%11111111

option_reg=%10000000
intcon = %10001000
I var byte

on interrupt goto int

main:
back: if portb<>0 then intcon=%10001000 ; test bit 3
serout porta.0,2,[254,1]
pause 10
serout porta.0,2,["Hello"]
pause 100
goto main

disable interrupt

int:

for i=0 to 5

serout porta.0,2,[254,1]
pause 10
serout porta.0,2,[#i]
pause 1000

next i

INTCON=%10000000 ; cleared bit 3 bit
goto back ; back to test
resume
enable interrupt
end


i will read document, thank u for that, and waiting a reply from Mister_e

[mister_e]

Micro,
Maybe your solution is working but will Behave weird one day or another.

I've nothing else to add from the Bruce's explanation. Everything is covered in his document.

AND it's also covered in the PORTB TRISB section 3.2 of your datasheet too.

BTW, why using interrupt on PORTB<7:4> if you never test wich pin gives you the interupt?

[Acetronics2]

i solved the problem with another method as below


if portb<>0 then intcon=%10001000

Just a longer way to read PORTB ... no other method here !!!

Elegant solution would have been to display the port where the interrupt came from, in the "serout"

Alain