Bryan Hord wrote:
>
> Modems:  Rockwell and MX-COM,
>
> We are using the Rockwell RC224ATL for an embedded 1200 baud FSK modem.  It
> allows for a serial or parallel interface and operation to 2400 baud.  If
> you are connecting it to a telephone system, it has the capability of
> driving a DAA (Data Access Arrangement - that's the transformer, filter and
> amplifier to connect to the telephone line) directly.  We are using it for a
> wireless application.  It supports the AT command set and also comes in a
> FAX/modem part RC224ATF.  It is very easy to use.  In small quantities they
> are about $10 from Marshall.  Does anyone know if this is the same part that
> came out in PC modems years ago?
>
> Another source is MX-COM.  They only seem to have serial interface parts so
> you need a UART as they require proper timing of the serial data.  Actually
> you don't need a UART since they have taken pains to make it tolerant of
> sloppy bit timings but the data rate needs to be accurate.  The MX-COM parts
> are cheaper than the Rockwell parts.  They have a web site with .pdf data
> sheets.
>
> Cermetek makes a complete modem module but it's really expensive.  It is
> probably the easiest solution if you want a telephone modem.
>
> What other sources of single chip modems have you found?
>
> Is this what you wanted or are you trying to actually build your own modem?

I want to make a home built modem for my PalmPilot (PDA from
USRobotics). The main reason is that the product specific modem costs
200 buck where i live. And although I CAN use any external modem. They
tend to be quite big in size. So i jus want to build a small modem (not
worrying about speed, because it's just to send e-mail).