[App_rpt-users] USB Sound Dongle Challenges

Andrew Errington erringtona at gmail.com
Fri Mar 18 00:30:20 EDT 2016

I have used CM108 and CM119 in the past, and the SSS1623, which is a
compatible chip.  You can get a datasheet for the CM119 here:

Unfortunately, if the chip is epoxy-blobbed you can not get to the GPIO
pins as they are not even bonded out- there is no connection to the die

I wondered if the mic. mute LED could be used to trigger PTT.  It should be
possible to turn mic. mute on and off under software control.  The mic.
mute LED line could drive a PTT transistor.  If mic. mute is on, PTT is on,
and you are sending audio out, so you don't need to get audio in, hence it
doesn't matter that the mic. is muted.

Even the cheap USB fobs have a mute LED on board (well, a lot of them do),
but the next tier up, with buttons, usually have them and obviously expose
the button pins too for CoS detect.

The cool thing about using the CM108 GPIO pins originally for PTT is that
it makes a neat assembly.  Audio Tx, Rx and PTT are all on the same board,
so a single, complete, USB device plugs into a single USB port.  This is
better, I think, than having just audio on the USB device and having to get
PTT from somewhere else.

Anyway, I wrote some software to link PTT to the CM108/SSS1623 GPIO and got
it going, then shelved it.  If there was a simple way in software to send
mute/unmute to a specific USB sound card then this idea could work.  I
looked a while ago, but didn't look too hard, or too long.


Andrew ZL3AME

On 18 March 2016 at 11:56, Thor Wiegman <n7jct at aplaceonthe.net> wrote:

> So I get that we're restricted to the C-Media chips.  That's fine, they
> certainly capable of way better audio than we're using on a 3K
> communications circuit.  It's a fine device for audio, way more excellent
> than we need.
> But why limit ourselves to using the audio chip for digital I/O?
> We already know that the parallel port can be used for this I/O (smoke 'em
> if you got 'em).  So it is possible to use something other than the audio
> chip.
> For applications with Raspberry Pi, what about using the GPIO pins?
> For Pi and all others why not a USB relay board?  Something like the IC
> Station ICSE013A would give us PTT and another relay for things like fans
> or whatnot for about $5.  For a few more bucks you could get the ICSE012A
> or ICSE014A and have even more output control.
> I've also seen some USB I/O boards for about $5 that give 16 pins, your
> choice of input or output on each.  If these could be adapted then
> chan_simpleusb could be used and the radio can provide COR and CTCSS.
> I'm just trying to think of ways we can use what we already have or to use
> cheap stuff that's commonly available.  I
> On 03/15/2016 06:51 PM, app_rpt-users-request at ohnosec.org wrote:
>> Message: 1
>> Date: Tue, 15 Mar 2016 22:05:54 +0000 (UTC)
>> From: Jim Aspinwall <no1pc at yahoo.com>
>> To: "app_rpt-users at ohnosec.org" <app_rpt-users at ohnosec.org>
>> Subject: [App_rpt-users] USB Sound Dongle Challenges
>> Message-ID:
>>         <504928773.650221.1458079554502.JavaMail.yahoo at mail.yahoo.com>
>> Content-Type: text/plain; charset="utf-8"
>> The original CM-108/-109-based products a few have documented mods for
>> are evaporating from common availability.?
>> A few of us have ordered or tried to order from "known good links" (circa
>> 2014/2015) off Amazon or eBay only to encounter
>> dead/expired/no-longer-available links or "byte the bullet" and opt for a
>> 108/109-claiming look-alike and come up with yet another version of
>> unusable product.
>> If we can determine the same/similar/equivalent pinout locations between
>> the 108, 109, 119 or whatever different chips we might be able to revise
>> some of the mod docs for alternatives.
>> However, the latest small batch I acquired came with not pin-exposed
>> chip-on-board (for which there could be more hope) but connection flooded
>> die-on-board implementations and drastically differently layout, no direct
>> access to pins without risking the chip trying to 'uncap' it.
>> Two recent acquisitions pictured:
>> http://www.no1pc.org/radio/NewerChip.jpg?- CM119 chip - one such device
>> has already been proven to work with IRLP and Asterisk via Pi - but I'd
>> like to do the PTT/COS tap-offs.
>> http://www.no1pc.org/radio/DieOnBoard2.jpg?- not yet sure of the chip,
>> but pinouts are obviously a challenge.
>> I can try to poke about and see if the exposed-pin CM119 is viable, if
>> someone familiar with the chips or their layout can advice. ?The
>> die-version - good luck?
>> Ideas? ?Existing updates?
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