[Xastir] Soundmodem

[Andrew Errington]

On Tue, 21 Jun 2011 22:54:38 Andrew Errington wrote:
> I am pleased to say that my code for driving PTT with a GPIO pin on a USB
> audio chip has been incorporated into soundmodem v0.16.  Currently it
> compiles for CM108 and other C-Media chips, but I have a patch which will
> allow the vendor IDs and product IDs for SSS1621 and SSS1623 audio chips to
> be recognised.
>
> I have tested it with the diagnostic functions (PTT test button) in
> soundmodemconfig, but it should work 'for real'.

I am further pleased to announce that I have successfully sent messages 
between two instances of Xastir connected to two instances of soundmodem 
connected to two USB audio devices connected to two radios (Yaesu VX2r and 
Yaesu FT-7100M).  The devices were connected to the same laptop, but they are 
conceptually separate.  The antennas were only about a metre apart.  My test 
was brief, but I believe it will work consistently.

I used two USB audio dongles based on SSS1623 with a PTT transistor added.  I 
discovered that SSS1623 needs a pull-down to stop the transistor being turned 
on when the device is plugged in.  SSS1623 has a pull-up on GPIO, CM108 has a 
pull-down.  Grr!  Obviously it's not a problem once soundmodem is running.

I also recently bought another USB audio dongle with an epoxy-blobbed chip.  
The chip is SSS1623, but the GPIO pins are not bonded out and not 
accessible.  :(

73,

Andrew
ZL3AME