On Sun, 8 Feb 2004 09:31:26 +0200, manolov wrote:

>I have PICDEM2-PLUS demo board with 18F452 , W2K , MPLAB 6.40,
>and running demo p18demo -project from Microchip
>
>Debugging and programming going well, but when I connect the board to my PC
>via RS232 cable I can not see the proper character on HyperTerminal.
>
>Coming strange characters as:
>Xfxx~~xffxxfxxxZpZpZpZpZpZpZpZpZpZpZp
>
>What is wrong with the RS232 communication?

Since you're getting *something* (even though the characters are
wrong), you've probably got your transmit and receive lines connected
correctly and not swapped. That's at least a starting point.

Is the demo board supposed to send a sign-on message or do you expect
it to send a continuous stream of characters? The documentation should
tell you what to expect.

This sort of problem is typically a baud rate mismatch between the
sender and receiver. The characters you see may give you a clue as to
how different the baud rates are.

If the demo board is supposed to be sending a message 10 characters
long and you're seeing 20 characters of garbage, the receiver may be
running about twice as fast as the sender. Generally, the more garbage
characters you see, the further off the baud rates are.

If the sender's baud rate is faster than the receiver's, you'l get
fewer garbage characters than are being sent. (In extreme situations,
you may get no characters displayed at all.)

> Is it normal to se such
>characters on Hyper Terminal.

No, of course not.


> I tried to set all possible settings

Why? The demo board must have some sort of default settings. You
should be able to find them in the demo board documentation. Just set
HyperTerminal to match them. Key things to look for: baud rate
(probably 9600 or 19,200), number of data bits (probably 8), parity
setting (probably none), number of stop bits (probably 1) and
handshaking (probably none).


>does somebody has such an experience here?
>I wrote a simple application in vb.net MsComm but the results are the same.

Again, why? HyperTerminal (or some similar program) is probably the
simplest means of establishing the basic link between a PC's serial
port and a device you want to communicate with. If that's not working,
there's very little chance that any application will work.


Regards, Bob

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