[aprssig] TNC2 KISS eprom

Curt, WE7U archer at eskimo.com
Mon Nov 7 14:37:07 CST 2005

On Mon, 7 Nov 2005, Scott Miller wrote:

> Who owns the tnc2kiss firmware?  What's the distribution license?  Would
> anyone mind if I offer tnc2kiss chips for a few bucks?

Make sure you know what flavor people want.  Here are some notes I
have on it, buried in the Xastir and SmartPalm sources.  I just
added JKISS to the list:

// Note about KISS & CRC's:  The TNC checks the CRC.  If bad, it
// drops the packet.  If good, it sends it to the computer WITHOUT
// the CRC bytes.  There's no way at the computer end to check
// whether the packet was corrupted over the serial channel between
// the TNC and the computer.  Upon sending a KISS packet to the TNC,
// the TNC itself adds the CRC bytes back on before sending it over
// the air.  In Xastir we can just assume that we're getting
// error-free packets from the TNC, ignoring possible corruption
// over the serial line.
// Some versions of KISS can encode the radio channel (for
// multi-port TNC's) in the command byte.  How do we know we're
// running those versions of KISS though?  Here are the KISS
// variants that I've been able to discover to date:
// KISS               No CRC, one radio port
// SMACK              16-bit CRC, multiport TNC's
// 6-PACK
// Multi-Drop KISS    8-bit XOR Checksum, multiport TNC's -,
// G8BPQ KISS         8-bit XOR Checksum, multiport TNC's -|-- All the same!
// XKISS (Kantronics) 8-bit XOR Checksum, multiport TNC's -'
// MKISS              Linux driver which supports KISS/BPQ and
//                    hardware handshaking?  Also Paccomm command to
//                    immediately enter KISS mode.
// FlexKISS           -,
// FlexCRC            -|-- These are all the same!
// RMNC-KISS          -|
// CRC-RMNC           -'
// It appears that none of the above protocols implement any form of
// hardware flow control.

If anyone has corrections to these notes, I'm all ears!

Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
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