Serial comunication problem

[mackrackit]

Post you code and configs along with a schematic.
Everyone is guessing as is.

[synsyn]

Hello,
Thank for reply and sorry for the late to answer but I was away for job.

I don't have much to to make experiment but I have try to change the
cable and the main circuit.
All is same I will get back the same garbage but...

Now i try to send the word "Hello" and now I get back on screen PC the
exact number of chars but with non ascii format like '¨µ¼´¿".

Yesterday I don't know how, maybe some change to prog or same hack
on circuit, for a short time I have get back the correct string on screen!
"hello"hello"hello"...

After that I have made some change and now all is come back in the
same garbage!

In anyway this is the source:
------------------------------------------------------------------------------
ANSEL=0
CMCON=7



TRISA = %11110000 ' Set PORTA to all input
TRISC = %00000000 ' Set PORTA to all input


Include "modedefs.bas"

DEFINE OSC 4

DEFINE DEBUG_REG PORTC
DEFINE DEBUG_BIT 1
DEFINE DEBUG_BAUD 2400
DEFINE DEBUG_MODE 0

DEFINE DEBUG_PACING 1000

Clear
Pause 1000

Cont var Byte

Cont = 0
Mainloop
PAUSE 1000
Cont = Cont + 1
Debug "Hello"
PORTC.2 = 1
PAUSE 1000
PORTC.2 = 0
goto Mainloop
------------------------------------------------------------------------------
And this the circuit:

[cncmachineguy]

I see you have a LED set to blink on for 1 sec, then off for 1 sec. Is the LED blinking and at the correct speed?

[synsyn]

Hi Bert,

I have fogot to say, it is only a luminose control to see if all work well(I don't have put it on the scheme).
And yes it seem blink 1 sec and 1 sec no. It's hard to say just lookin at it
but the time seem correct yes.

[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