[aprssig] Re: [nwaprssig] KPC+ and uiview and GPS

Curt, WE7U archer at eskimo.com
Fri Aug 11 11:58:01 CDT 2006

On Fri, 11 Aug 2006, Tyson S. wrote:

> I am trying to run uiview and a KPC3+ and a GPS all on one serial port,
> is this possible? I tried a USB to serial converter but the laptop
> keeps crashing and locking up with the thing plugged in. I heard that
> you can use a special cable and run everything through the one serial
> port but I do not know how. I am using KPC-3+ with version 9.1 software.

It's called an "HSP" adapter.  You can build your own.  I did.  I
wouldn't recommend using one though.  The idea is that the computer
application switches the computer's RS-232 receive line between two
serial ports, using a handshake line on that port to control it.

Some APRS applications know how to do this, doing the HSP switching
to get the data from a GPS periodically.  The rest of the time
they're receiving from the TNC.

The reason I wouldn't recommend HSP is that the computer doesn't
know when you're in the middle of receiving a sentence from either
device, resulting in some garbled APRS and GPS sentences getting
received by the computer.  You'll also miss any APRS packets that
come in while you're listening to the GPS unless the TNC holds off
sending characters during that time due to the handshake.  You'll
still chop up sentences at the switchover points in any case though.

Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
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