[arm-allstar] Radioless Node -- Current state of GPIO PTT?

[Mike Glauser]

I’m looking to build a Radioless node and would rather not set up a USB interface… 
What is the current state of being able to key PTT from GPIO?

I already have a USB Microphone I could bring into the Pi.  (A Blue Snowball)
 and already have a 12v 10watt external stereo amp for driving speakers (it’s in the parts bin) from the stereo output.



Recommendations?

Options I know of are DMK Engineering’s URI and RA-42, but these add a lot to the cost of the unit.