Serial Timeout Strange Issues

[Corbet]

Hey all,
I am having a strange issue that has been driving me crazy for a couple weeks. Today I figured out how to recreate my problem.
I have 1 chip sending a serial signal and one receiving. The sender is a PIC16f684 and the receiver is the PIC16f84. I am using the serin2 and serout2. The serout2 works fine but when i have a timeout in the serin2 that is longer than the delay in the sender program, the program hangs up on the serin2 statement. What I mean by this is i had the sender chip counting and sending the result through serial to the receiver. The sender sends the serial and then i have a pause in an infinite loop. If the timeout length in serin2 is shorter than time between the serout2 commands then the serin2 hangs up.

The end goal is to have a chip refresh servos every 20 ms with angles received through serial. If the sender takes too long i want the sender to wait till the receiver is ready then send but I need the receiver to be able to timeout and refresh the servos.

Thanks,

[mackrackit]

Any noise on the line will cause the time out to be reset. Is this an RF project?

[Corbet]

No both chips are on the same board about 2 inches apart with a wire going through a 1k resistor to the other chip. How do I filter out the noise, if any, without filtering out the signal?

[mackrackit]

Noise should not be the problem then.

Post your code and we will see if there is anything there.

[Archangel]

I am guessing you are powering the pics from the same supply as the servo. A little electric motor like that can generate some serious voltage (back EMF) and distribute it back into the power supply. I would power them seperately and tie the grounds all at a single place.

[Corbet]

No the servos and chips have seperate power supplies with connected ground as I ran into that problem before
Here is my code

Receiver

Define osc 4
trisa = %000000
trisb = $00
low portb
t1pulse var byte[6]
t1pulse[0] = 90
t1pulse[1] = 90
t1pulse[2] = 90
t1pulse[3] = 90
t1pulse[4] = 90
t1pulse[5] = 90
porta.1 = 1
porta.2 = 0
trisa.3 = 1

Main:
porta.2 = 0 'turns on a transistor that brings pin on sender high
'to stop it from sending the serial

pulsout portb.3,t1pulse[0] + 60 'pulsout for servos
pulsout portb.2,t1pulse[1] + 60
pulsout portb.1,t1pulse[2] + 60
pulsout portb.4,240 - t1pulse[3]
pulsout portb.5,240 - t1pulse[4]
pulsout portb.6,240 - t1pulse[5]

porta.2 = 1 'turns transistor on to bring sender pin low to
'tell sender to send

Serin2 porta.3,84,15,Comfail,[wait ("@"), str t1pulse\6] 'if timeout length
' is longer than the time between the sends
'on the sender, this line hangs up and chip
'acts weird like turning porta.2 on but not
' sending the pulses or turn on servo pins
' and never turn off

porta.2 = 0 'tell sender to stop sending

goto main 'loop to main

Comfail: 'if sendin timesout, go here.
Porta.2 = 0 'tell sender to stop sending
goto main 'goto main

The sender does some calculations and sends an array of size 6 through a pin and doesn't do anything else with that pin, just serout2 and then continues on with the program. If the time it takes the sender to send is longer than the timeout the receiver doesn't work correctly.