PIC18F PORTB Interrupt Problem

[Amardeep]

I am using PIC18F4520 MCU
I am try to implement interrupt on PORTB RB4:RB7
interrupt is works ok but RBIF is still 1 even RBIF=0
as per information on datasheet..
"The input pins (of RB<7:4>) are compared with the old value latched on the last
read of PORTB"
i did experiment on some condition to input like:
1) made high to low state and maintain pin at low
2) made low to high state and maintain pin at high
3) made high to low state and maintain pin at high
4) made low to high state and maintain pin at low

but still RBIF is high and it become cause of recursive interrupt.

any sugesstion.??

 

[xpress_embedo]

Thr interrupt on these pins occur on change.

have you read datasheet properly.
read datasheet and read about portb mismatch

i had used this interrupt to interface keypad and it works fine

- - - Updated - - -

Thr interrupt on these pins occur on change.

have you read datasheet properly.
read datasheet and read about portb mismatch

i had used this interrupt to interface keypad and it works fine

 

[Amardeep]

yeah i had reed datasheet properly .. but i am still confuse what is mismatch condition ..??

example: by default state on pin is high then i did high to low transition and again made pin high ...
i found recursive interrupt.
what would be the problem ?

 

[xpress_embedo]

When you get interrupt on high to low transition
Then read the portb status and then write 0xff to port and wait unitil it gets high.
This will protect your recursive interrupt as you are stopping interrupt on low-high transition

 

[Amardeep]

Hello Sharma Ji ...
its works ... and RBIF is Zero after interrupt thanks alot