CANbus not working after a few messages

[smoglu]

Hi. I am working on a CAN bus project. There are two (actually many but for now only two) nodes on bus, each of them is a 18F458 (with MCP2551 of course) connected to LCDs. In one of them, two buttons are connected to ext interrupt 0 and 1 as well (a main node). I use interrupts for CAN communication as well.

Now when I press button 0 at main node, other should display "Kat: 0", and when I press button 1 other should display "Kat: 1". As I continuously press buttons, after a few correct displays at other node, it stops changing the display as I press other button, the same number stays at display. Interestingly, this "a few times" of correct display also changes. Sometimes it goes for 7-8 correct displays, sometimes after only 2 displays (i.e. I press both buttons only once) they stop changing. When I reset the other PIC (and not reset main PIC), it again changes correctly. Can anybody see what is the problem?

I constructed my circuit on breadboards. My compiler version is 4.068.

By the way, do I need to clear interrupts at the end of isr or does compiler clear them automatically?

Thanks for help.

[newguy]

Your problem is that you're doing something (printing to the LCD) which takes a LONG time, inside an interrupt service routine. If a new CAN message arrives before the first ISR has been serviced, bad things can happen (as you've seen).

Change your code to do virtually nothing inside of an ISR. Simply set a flag (eg message_received = TRUE;), which your main() loop will see and act upon. You won't see this problem again.

[smoglu]