Trouble sending RS232 commands to a projector

cap110874 · Guest

Hi

I am trying to send rs232 commands to turn a projector on and off.

If i test in a hyperterminal or similar I type
"~0000 1" and then hit returm on the keyboard.
This turns on the projector.
"~0000 2" and then hit returm on the keyboard.
This turns off the projector.
All ok from hyperterminal
but when i use me pic 18f2525 too generate nothing happens. Testing with hyperterminal i am getting the commands but the dont do anyrthing to the projector. Looks like the carriage return is not working but cant work out why.

Code being used is:
if (last == turnOn)
return;

fputc(0x0D, STREAM_UART); //c return
if (turnOn)
fprintf(STREAM_UART, "~0000 1");
else
fprintf(STREAM_UART, "~0000 2");

fputc(0x0D, STREAM_UART); //c return
last = turnOn;
}
break;

asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

U may get an answer if you post your
compiler version
and a short example of your code ( WITH FUSES FOR SURE )
that JUST shows your communication setup

and no other stuff.
PS make sure it compiles w/o err before posting ok ?

BTW- what HARDWARE are you using to interface the PIC to said projector?

can you connect the pic via a nullmodem to HYPER term and SEE what you are sending ?

can u post a PDF or JPG of the schematic ?

cap 110874 · Guest

asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

Format strings

Gabriel · Joined: 03 Aug 2009 Posts: 1067 Location: Panama

hello,

You should find out if your projector uses flow control...
(pins 1,4,6,7,8) on the DB9 Cable).
You can figure this out by making your own cable, using only pins
2,3, and 5..... null modem cable... as mentioned before.

I had a similar problem with a cellphone.

Also, check if hyperterminal is sending extra characters.

Use Siow instead of hyperterminal. (siow comes with the CCS compiler)

This is a basic solution... so simple, it gets overlooked often.

Hope this helps.

gabriel
_________________
CCS PCM 5.078 & CCS PCH 5.093

SherpaDoug · Joined: 07 Sep 2003 Posts: 1640 Location: Cape Cod Mass USA

Try sending commands from the PC using a macro vs. typing character by character. Maybe the projector needs spacing between characters to work or its UART buffer overflows. If you have a scope or simple logic analyzer you can see character spacing.

Also try changing your baud rate by +/- 2%. Maybe the PIC or projector baud rate clock is a little off.
_________________
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