[Xastir] Baycom

[Christian F1GWR]

Hi,

OK Henk, I'll forget my Baycom modem. BTW did you think about 
association of Xastir and your fantastic DigiNed? Or is it already 
possible " in a simple way"?

So I'll try my real TNC2 and start a new thread for this specific 
question which is also questionable.

73's
Christian F1GWR

Le lundi, 9 juin 2003, à 17:44 Europe/Paris, Henk de Groot a écrit :

> At 11:16 9-6-03 +0200, Christian F1GWR wrote:
>> 2 I own a Baycom KISS modem, tied to a (perfectly working) Keyspan 
>> USA28X USB-serial converter.  With the ZTerm application, an 
>> oscilloscope shows that Start-stop signals are present on DB9 pin 3. 
>> The thing is Baycom doesn't use pin 2 & 3 but DTR 4 (20) FOR TxD, CTS 
>> 8 (5) for RxD, and RTS 7 (4) for PTT. Is this modem Xastir (serial 
>> KISS TNC option) compatible? Beside that, am I to install AX-25 >> 
>> layer?
>
> This is not a KISS modem but just a BayCom modem. A BayCom modem is 
> just a modem chip and some very simple interface electronics. It is 
> conencted to the serial port but does not realy make use of the serial 
> port capabilities, you can also connect it to the LPT port! The COM 
> port makes asynchroneous serial data but on air synchronous serial 
> data is used, so the serial port data can't be used as is. So instread 
> the BayCom group just used the serial port in an unusual way. The 
> serial port TX line is used to power the modem and the CPU constantly 
> monitors the CTS line to read the serial data. For 1200 baud the CPU 
> reads the CTS line 3600 times per second so every bit is sampled 3 
> times. By watching the bit changes the PC can stay synchroneous with 
> the data and decode it. For transmission the PC just puts the data on 
> DTR, this requires a stready 1200 Hz interrupt.
>
> There are hard timing constraints and to meet those direct access to 
> hardware, interrupts and PC timers are needed. On the PC this works in 
> DOS, with a special AGW driver in Windows and with a specialized 
> driver in the Linux kernel. On a MAC I think you are lost, I'm not 
> aware of any implementation for BayCom style modems on a MAC.
>
> The best is to use a real KISS TNC. A good alternative may be John 
> Hanson's (W2FS) KISS modem which appeared in QST of November 2000.
>
> At the end of thr article it says:
>
> "A complete kit of parts including the PC Board, a programmed PIC 
> 16F877 and all other parts (except an enclosure) are available for $65 
> from John Hansen, W2FS, 49 Maple Ave, Fredonia, NY 14063."
>
> I think with Google you can find more references and information.
>
> Kind regards,
>
> Henk.
>
>