Processor halts : Please help

[cwmaddy]

Hello All,

I am trying to build a telephone line interfacing circuit. There are two switches in the circuit(Pick up (PU) and hang up(HU)) I wait to see the line ringing. If during this time pick up switch is pressed, I pick the line. On hang up switch, I go to hang up the line by activating relay.

If I do this repeatedly, my PIC hangs . It sometimes hnags in hangup code section. (Please see attached code) There is no pattern or timing sequence in this hanging. Things come back to normal after 50-60 seconds.

I have used trisb to make portb high. This trisb stops working when I execute hangup. I have to again pull them all high. This was putting the unit in oscillations earlier. This is working by initializing trisb again,but ideally this type of modification is not required. I need to understan if something is wrong in the code.
I am confused. I need to find out the reason and remedy for this problem as it is very important for my unit to be fault tolerent.Please help
Thanks in advance.


cwmaddy