Linux Programming Discussions

Martin McCormick martin at
Wed Sep 1 01:38:50 UTC 2010

Christopher Brannon writes:
> Yep, this is a buffer overrun.  Additionally, the OP isn't
> checking the return value of read().  It returns -1 on failure, in which
> case, it should not be used as an index into the buffer.

	Even though I am not supposed to be receiving anywhere
near a full buffer's worth of data, it has got to be a reference
pointer problem of some kind. I did experiment with a smaller
buffer but nothing changed. One would have expected the garbage
data to be different but it was always  the same string

	When I figure it out, I will tell you what I found. I
know that the serial routines under Linux are supurb so I am
sure I just have something configured wrong.

	I spent the first day perplexed because I wasn't even
sure whether I needed a null modem or not. I couldn't get
anything to come back. It turns out that the hardware flow
control needs to be absolutely shut off as the radio doesn't
even fake it by leaving the correct lines on all the time. If
your communicator program is looking to use CTS or RTS, you will be
waiting forever. As soon as I took that out, it started talking
big time. I was never so glad to see an error message in all my
life. If you send anything other than a valid command, even an
empty carriage return, the radio responds with "ERR" I almost
think I hear it laughing at me.

	Thanks for all of your suggestions.


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