Javelin Stamp RS-232 Question

rich_mays

I am attempting to use a Javelin Stamp with a MAX233 IC to communicate with an RS232 device.· I send a string to the device, but the timeout on the reply always expires (the timeout is set to 5 sec).· If I try to reset the stamp or reprogram it, I get a serial communications error (0022).· I can 'unstick' the stamp by removing it from my board, plugging it into a BOE and programming it there.· After that, it will work for another iteration in my board.

My first question - have you seen this problem before, and do you have any suggestions from fixing it?

Second - I am using the Vdd on the Javelin stamp to power the MAX 233.· Could this be the reason serial comm is failing in the first place.· I measured a voltage of 4.8V on the power pin of the MAX 233.

Any help would be appreciated!

Rich

Peter Verkaik

I have used the javelin vdd output to power 2 max232 ic's without a problem.
The vdd output can deliver approx. 90 mA.

You say, when you send a string, the timeout expires,
so I guess the string is not received. Could be the baudrate,
logic level (inverted or not) or missing handshake signals.

Post the serial protocol for your device,
and post your javelin program that implements
that protocol.
Then we can see what might go wrong.

regards peter

GJ

I also use a max232 and it works well, actually I think it is a max222, but pretty much the same thing.· I have had the problem you have. It was caused by having tx and rx backwards. you may want to check this.·

rich_mays

GJ,

That was it. Thanks!

Rich