Re: Linux Packet Interface Hardware

["Curt, WE7U" <curt.we7u@xxxxxxxxx>]

On Wed, 16 Jun 2010, Jim Kusznir wrote:

> 2) When switching to KISS mode, all the parameters specified in the
> non-kiss mode are ignored.  So I'm running with "default" tx delay,
> etc.

You can send custom-crafted KISS packets to the TNC which set
various KISS parameters.  Assuming you have set your serial port
parameters you can do things like this:

    #!/usr/bin/perl
    sleep 1;
    printf("%c%c%c", 192, 255, 192);
    sleep 1;


Which is the "kiss-off.pl" script from the Xastir project.  Run it
against a serial port like this:

    ./kiss-off.pl >/dev/ttyS1


See the KISS spec (online) for the parameters you can set.  The
above script takes a TNC out of KISS mode.  Again I'd mess with the
p-persistence and slottime parameters.  Looks like default TXD is
1/2 second though which is a bit long so mess with that too.

The above 192, 255, 192 sequence is FEND RETURN FEND.  Assuming
you're not messing with a multi-port TNC so that we can assume the
upper four bits to be 0, you'd set parameters like so:

    FEND 0x01 0x20 FEND   # TXD in 10ms units
    FEND 0x02 0x40 FEND   # P-Persistence
    FEND 0x03 0x0a FEND   # SlotTime in 10ms units

or:

    192 1 32 192
    192 2 64 192
    192 3 10 192

Make sure that if 0xc0 or 0xdb appear in your data that you use the
escape characters as mentioned in the spec.

--
Curt, WE7U.                         <http://www.eskimo.com/~archer>
   APRS:  Where it's at!                    <http://www.xastir.org>
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Windows:  Microsoft's tax on computer illiterates. - WE7U.
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