>There should be some kind of written document on this. Looking at the
>source code to TNC-2 is not sufficient for my needs, as my time is quite
>valuable to me.
There is. I've downloaded a ax25.doc some time ago. I'm sure you'll find
it somewhere on the web. (If not I could search it on my backups)
Depending how deep you really need to go almost everything you'll require is
included there, I think. I'm wondering if you really need to go down to
layer 1, because
there are already enough modems (speaking only of the implementation of the
modulation not
about the scc's which generate the nrzi) for all baudrates ready to use.
Just care about the
upper layers and then you could attach anything you want - beginning with a
TCM3105 used for 1200Baud FSK Bel202 up to some more compilcated circuits
with PSK/QAM and scambling mechanisms.
3 years ago I used this ax25.doc document as a reference to build my own TNC
as a
project for school.
I didn't had TF2.7 sources, only had ax25.doc and the datasheets for the
chips. I've done software and hardware on my own and it worked perfektly.
The hardware consisted of a i80196 microcontroller, i8273 hdlc controller,
TCM3105, GAL16V8 for address decoding, SRAM, an alphanumeric
display and a keypad.
I've also done some dumps with an logic analyzer and a multi-protocol
data analayzer of different packet types.
I don't know what you are going to do, but if I can help you with a specific
problem, let me know.
Robert
