[App_rpt-users] USB FOB pin 13 (PTT)

[Ken]

The new URIx (as it is called) uses the CM119A.  If you want to roll your
own, it would be a good idea to find a fob that uses one of those.

I would note that the output of the chip itself is unlikely to be able to
drive much of anything. Again, looking to the URIx design, they use a FET
switch (IRLML2060) to buffer the output.

To force the PTT on you simply use the command "radio key" and "radio unkey"
from the Asterisk CLI

GL
Ken



> -----Original Message-----
> From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-
> bounces at ohnosec.org] On Behalf Of Andrew Errington
> Sent: Sunday, December 04, 2011 9:27 PM
> To: Larry
> Cc: app_rpt-users at ohnosec.org
> Subject: Re: [App_rpt-users] USB FOB pin 13 (PTT)
> 
> > First ... I'll comment on the USB unit.... The chip within is covered
> > by a blob but it detects as a CM-109 and appears to function properly
> > as far as audio and COS ... only the PTT logic has failed to output
> > during my limited testing.
> 
> If the chip is epoxy-blobbed, how can you connect to pin 13?  GPIO is
> not required for basic sound-card functionality, so it's often not
> bonded out from the die.  It's quite possible that you simply can not
> access GPIO.
> Of course, since I haven't seen your device it's quite possible that
> you can access it after all.
> 
> Another possibility is that the GPIO you can access is not actually
> GPIO3, the one that is usually bonded to pin 13.  You can get the CM109
> datasheet on-line and you can see there are 8 GPIO pads on the die.  If
> a different GPIO is bonded out then could you change the app_rpt
> configuration to drive a different bit number?
> 
> 
> > My assumption about the actual sequence within the chip process was
> in
> > line with your great explanation. What I lacked is understanding if
> > there is a way to force the software into a transmit mode for testing
> purposes.
> > Doing so, as you explain should activate the PTT logic.
> 
> Well, I don't use app_rpt, but maybe there is a test function you can
> use.
>  It would be quite handy for debugging.
> 
> 
> > Your info about Thomas Sailer's soundmodem is something I am very
> > interested in. I had another project in mind and decided to venture
> > into Asterisk and App-rpt in order to to utilize USB sound modules.
> >
> >
> > Your information may very well be a solution to another problem I
> > would like to tackle. I will definitely have a look.
> >
> 
> Feel free to email me on- or off-list.  I'm no expert, but I have
> dabbled a lot, and I have absorbed a lot of the information that others
> have written on this topic.
> 
> Sadly the CM108 packaged parts are becoming scarce as manufacturers
> move to the cheaper epoxy-blob process.
> 
> 73,
> 
> Andrew
> ZL3AME
> 
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