Serial comunication problem

[cncmachineguy]

Well that would seem to rule out any OSC issues. The Pic is running and running at 4Mhz as you have programmed for. At this point, I think I would just have it run and start touching stuff. Maybe there is a breadboard problem or something like that. If it worked yesterday, even just for a few times, it seems like the code is good. So the only thing left is hardware.

Wiggle the caps while watching the PC to see if "hello" magically appears. also all the wires. Do this 1 at a time to try and isolate the problem.

Maybe even try a different output pin, Or move the parts around on the BB. I have had BB's fail on a pin here and there from the socket not making good contact.

[synsyn]

Well that would seem to rule out any OSC issue

Yes I think the problem is there, but maybe in the code or maybe I dont' sent
some registry of 16f676 IC.

I say this because I have change the PIC circuit in a 1000hole board and I get
the same garbage.
I think to have change something in the code about OSC define or something
aroud and the serial work.
I anyway I can wrong, but the only thing ever same is the MAX232 circuit,
but there is only some condensator so I can see any thing wrong.

Maybe some one have made the same circuit with PIC 16f676 and Max232
and he can check if the code, expeccialy the Oscillator define, is correct ?

[ardhuru]

Why dont you try bypassing the Max232 and use Debug Mode 1 to rule that out?

And I just noticed you're using the 16F676; are you sure your OSCCAL value is intact?

Check this outhttp://www.picbasic.co.uk/forum/showthread.php?t=15268

Regards,

Anand Dhuru

[Charles Linquis]

You can do a pretty good "no equipment" check of your oscillator by turning ON a LED, issuing a PAUSE 60000 and then turning it off. Even with human error, if it is ON for a minute, you should be within 2%, which is close enough for communications at 9600 baud. If you want to get even closer, issue the PAUSE 60000 10 times in a row. Turn your LED on at the beginning and off at the end. It takes 10 minutes, but you can easily get much better than .5% accuracy that way. The PBP PAUSE command is *VERY* accurate.

Also, I highly recommend Bray's terminal program
https://sites.google.com/site/terminalbpp/

It works with high-numbered COM ports (useful if you are using USB <-> 232 devices). It works with
Windows 7 (which does NOT have Hyperterminal), and best of all
It lets you choose non-standard baud rates. If your PIC is running 5% fast, you can choose 1080 baud if
you like (not all baud rates may be attainable with all hardware, but the software does a great job).

[Charles Linquis]

Oh, and QUIT using those 16F chips! 18Fs are so much better and don't cost any more.

[Normnet]

Oh, and QUIT using those 16F chips! 18Fs are so much better and don't cost any more.

I second that.

Norm

[cncmachineguy]

Not to continue hi-jacking this thread, but I have to a little. What is so bad about the 16F's? They are easier to configure if you are new to datasheets, work just as well (both 8 bit). OK, less memory, but who needs it for starting out stuff? I have a couple of products running 16f676 that have been going strong now for 8 years I think. Work fine!

I am starting to play with the 18's, but really just because.

[Charles Linquis]

Yes they work, but the forum would run a little smoother if most everyone was using the same series of chip. I'm sure MELabs thinks that way also.
The fact that you can easily get parts with large codespace is such a bonus. You can add features over the years without
changing much.
90% of Microchip's really neat parts in the 8-bit realm are in the 18F family (18FxxKxx, 18FxxJxx).
If you write some routines in ASM, it is much nicer to not have to deal with endless bank switching.
You can use LONGs and 2000 element arrays.
Even if you don't need all the neat stuff now, why not get a chip that has the peripherals and codespace now so that you can learn to use the extra features in your spare time?

And they don't cost more. Easy decision for me. I'll be quiet now.

[synsyn]

And I just noticed you're using the 16F676; are you sure your OSCCAL value is intact?

Check this outhttp://www.picbasic.co.uk/forum/showthread.php?t=15268

Regards,

Anand Dhuru

Hi Anand,
I have tried today your example and I did some experiment,
and of corse it works very good!!!
It's a easy way to use the PIC with internal oscillator
in serial comunications, or other critical tasks where timing
is crucial, without the use of an external quartz.
Thanks a lot for your advice.
Regards,
Gabriele

[ardhuru]

Glad it helped, Gabriele. Now that you have the calibrated OSCCAL, you could fairly safely ramp up the baud to 9600.

Regards,

Anand

[synsyn]

Oh Yes now I can Burd the Sky!!!
Thanks again to have helped me and for knowing on forum.