[App_rpt-users] USB FOB not affecting Pin 13 to PTT

Marshall Oldham ke6pcv at cal-net.org
Fri Nov 25 13:32:27 EST 2016


Jim, 

 

Certainly your time of building a USB FOB to DB25 interface is worth more than the actual cost of purchasing a URI at a ham discounted price. 

 

I would just buy a URI and save all the time and headaches , they work!

 

73

 

Marshall - ke6pcv

 

 

From: app_rpt-users-bounces at ohnosec.org [mailto:app_rpt-users-bounces at ohnosec.org] On Behalf Of no1pc at yahoo.com
Sent: Thursday, November 24, 2016 12:21 PM
To: App_rpt-users at ohnosec.org
Subject: [App_rpt-users] USB FOB not affecting Pin 13 to PTT

 

 

I have a few USB fobs resembling the one shown in the document titled "USB FOB to DB25 Interface" 

 

Unfortunately the chip itself is potted die-on-board so access to signalling lines is limited to the additional components on board, which should seem simple enough to get to Pin 13 that feeds the Red LED to extract a PTT signal.

 

(I am able to assert COS- to Volume down and get received audio "to the net" experienced with WebTransceiver.)

 

Unfortunately metering 'every' available connection and toggling WebTransceiver's Key/Transmit, none of the signal lines on the board react.  I could imagine one line or the other might be open-collector and I'd have to add a pull-up to see a transition, but with the LED still in-circuit I'd think that would react.  (The Green LED works as heartbeat just fine.)

 

Before I head to the local Frys and buy 1-2 each every fob they have to gut to see if I could get to the chip pins directly (or try to be patient and wait for Amazon)...

 

... I'm sitting here looking at a fully functional micro with a LOT of GPIO pins available...  wondering why, aside from the IRLP s/w and interface options available... doesn't an AllStar implementation leverage the on-board signalling?

 

I see there is Python code around to work with the GPIO, but not quite yet sure how or if I could create and call PTT and COR (and CTCSS) sense scripts within the AllStar configuration - ???

 

I know it would split out the radio audio v PTT/COS wiring harness just a bit vs the cute USB thing, but what the heck - buffer/interface parts on a small perf board tied to the GPIO pins and done?  No?

 

Am I missing something?  Code- and instructions-to-be?

 

Using Pi 3 Model B v 1.2

 

BTW, uname -a yields: "Linux barf3 3.18.0-trunk-rpi2 #1 SMP PREEMPT Debian 3.18.5-1~exp1.co1 (2015-02-02) armv7l GNU/Linux"

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