16f690 crashes

[Melanie]

You are trying to do a timing-critical function (Serial Comms) on a PICs crappy internal oscillator, and you're wondering why it's not working?

But that (and other horrible things) aside... you should have a GOTO POLL, not a GOSUB POLL. You're filling up your stack and promptly dissapearing destined never to RETURN...

Also... when you have a problem and you jump to NXT (I haven't checked the syntax of your SERIN command btw), it performs a GOTO and NOT a GOSUB... therefore it's NOT a subroutine so the RETURN statement is not valid.

[Lincoln S.]

ok.. I'll go ahead and clean that up and post it again..

[Lincoln S.]

heres the new cleaned up version of the old code. I haven't hooked it up to the pc but this one seems to work just great (it pulses the pin selected for output). I did that stuff you were talking about with the goto command. thanks for the help.

as for the xtal, yeah, I'm going to have to condede to that. I was hoping to see if I could just get by without one, but I'm going to probably have to give those pins back to the xtal. I was kinda getting away without needing an xtal due to the fact that nothing else was hooked to it whilst I was testing this code.

I've also been looking for a tutorial on setting all pins on the device to digital. it seems the settings I have do that, but I really don't have a clear understanding off the following ansel, anselh and adcon. I looked in the microchip pdf but it was rather confusing.

thanks for the help with the code.

INCLUDE "modedefs.bas"
define osc 4

@ device PIC16f690, MCLR_OFF

info var byte[5]



trisa = %00000000
trisb = %00000000
trisc = %00000000

ansel = 0
anselh = 0






poll:
        
        
        
        
        pause 100
        SERIN portc.5, N2400, 1000, nxt, ["r"], info[0] 'Get input
        SERIN portc.5, N2400, info[1] 'get the word "relay"
        SERIN portc.5, N2400, info[2]
        SERIN portc.5, N2400, info[3]
        SERIN portc.5, N2400, info[4]
        
        
        SEROUT portb.7, N2400, [info[1], info[2], info[3], info[4] ]
        
        
        pause 500
        
        
        
        
goto poll
	
    
nxt:
    serout portb.7, N2400, ["timeout"]
goto poll

[mackrackit]

A tutorial for the analog settings would be great, but this should help some
http://www.picbasic.co.uk/forum/showthread.php?t=561
and here is a way to use the ADC that is a little different than the manual, I still prefer this method.
http://rentron.com/PICX2.htm
Read through the above example, when you understand how it works it should really help you understand the inner workings.
Post your questions.

[Lincoln S.]

hey, my code is working great, but I have been running into some problems with noise. I geuss I should state the problem first. I am trying to get both input and output working on about a 1 foot long straight (four wires untwisted parrallel) serial cable to a PC. it worked ok before when I was just using on line and a ground, but now that I have input and output lines going to the pc, I get noise on the other line everytime I use the serout command from the pic. tried using 10k pulldowns (not being sure about the connection on that I ran 10k from data line to ground and the unused in from the pc as well). that didn't work. then I tried a 10 mf electrolytic on the unused line with neg side going to ground. this worked but it didn't quite seem kosher to be putting a 10mf electrolytic on a line of this sort, especially going to a PC serial line.

is there perhaps a post here with few help hints and some schematics showing how to reduce noise on straight cabling? I been looking for quite some time for some info to glean.

also worth noting, when I ran this pic (16f690).. just on the protoboard with intosc and nothing but power, I got no noise, so it is the parrallel capacitance of those wires doing it. recon I could try some cat5 I have lying around.. would be interested in all things noise reduction however.

I added an xtal btw. specs say +- 1 but in the area of millions of cycles per second, that could be a deal breaker.

thanks for any help. thanks for the help you allready gave me.

[mackrackit]

then I tried a 10 mf electrolytic on the unused line with neg side going to ground. this worked but it didn't quite seem kosher

Capacitors are the best way to reduce noise. I would guess the unused line is acting like an antenna and the cap is suppressing it.

[Lincoln S.]

huh.. I tried that electrolytic 10 mf cap. works fine across unused line from the pic. but I started wondering what it might do to the waveform of the incoming pc. I put it accross the pic out, and it went from high/low pulsing to low pulsing. anotherwords the cap is too high. I recon I'm going to have to pull out the old cap box I salvaged some years back and try some various values. I recon its about time to re-stock on the salvaged caps, the goo inside is prolly starting to dry up on the old ones. man.. I sure hope I don't have to find a scope to do this with, that would be a pain in the rear.

gotta hammer away some more and try to find some solutions. I think I am going to replace the wires with twisted pair cat 5 and see what that does.