Hi,
Your schematic with the FX614 has the exact pinout of the MX614 so it looks like the
same
chip. I see that you use a uart design for your modem. The design that I am using
(designed by a guy named Paul Breed for his own project) hooks up to a microcontroller
instead of a com port so the controller side circuitry is a bit different. M0, M1,
Rxd,
Txd, and the energy detect pin each have independant lines to the microcontroller.
Also
another difference is the Clk and Rxeq pins are not used. Instead a timer in the
microcontroller polls the Rxd pin to receive data at 1200baud. I start polling the
Rxd line
when the Det (receive energy detect) line goes high. I'm still working on this code
to get
it sampling the Rxd pin properly in the middle of each received bit. Any help on this
would
be fantastic!
The audio hookup to the mic and speaker are basically identical except for your design
you
have the M0 status to turn the PTT/VOX on/off. M0=1 for Tx and M0=0 for Rx The
design Paul
made uses a seperate microcontroller pin -> transistor to turn the vox on/off.
I am planning on coding in the AX.25 protocol into the microcontroller and putting it
in the
rocket we are making then using the linux AX.25 package with the soundmodem to
communicate
with it.
cheers,
Jamie
http://142.104.54.173
Gerd wrote:
> Hello Jamie, hello all,
>
> > i am using a Bell 202 compatible modem chip (mx614 - www.mxcom.com) in the design
>I am
> > doing. Is this afsk? The datasheets I have only say fsk. I guess it is probably
>afsk
> > since the chip outputs 1200hz/2200hz audio tones. Is fsk carrier frequency
>shifting?
>
> Should be. But, if you are really brewing a mx614 based modem -
> could you then tell me (hopefully, this will be of interest to others,
> too) about your experiences?
>
> I happen to have a schematic available on
> http://www.ardos.de/gerd/fx614.html - it is based on the FX614. Is
> this the same chip as the MX 614?
>
> Thank you very much for any hint in advance.
>
> Cheers
>
> Gerd
> --
> Gerd Roethig
> Universität Leipzig, Medizinische Klinik u. PK I
> Johannisallee 32, 04103 Leipzig
> Tel. (0341) 97 12622, Fax (0341) 97 12515
