I am trying to use a Digirig Mobile (rev 1.9) as the radio interface for an AllStarLink node on a Raspberry Pi, with an Icom ID-5100 on the audio/PTT jack. I have the appropriate cables for my ID-5100/Digirig config
The board enumerates correctly (0d8c:0012 C-Media and 10c4:ea60 CP210x). Audio is present. In simpleusb-tune-menu, option T toggles PTT and the round PTT pad (CM108 GPIO3) goes to about 3.3 V when keyed and low when idle.
The audio-jack PTT line never keys the radio. From the schematic and the Digirig forum, the jack PTT (ring 2 / RIG_PTT) is an open-collector driven by the CP2102 RTS pin, not by CM108 GPIO3. GPIO3 only goes to the PTT test pad. ASL3 SimpleUSB has no ptttype=RTS (or equivalent). It only toggles the CM108 GPIO, and invertptt only flips that GPIO. So stock, AllStar never drives the transistor that pulls the jack PTT to ground.
A direct connection from the PTT pad to the jack pin does not work either. When AllStar keys, that pin rises to 3.3 V instead of being pulled to ground, and the ID-5100 does not transmit. The radio expects an open-collector ground on its PTT pin.
What is the recommended way to get AllStarLink PTT working on a Digirig Mobile rev 1.9? Is there a supported software path for RTS/DTR PTT in ASL3, or a specific jumper/mod that connects CM108 GPIO3 to the existing jack PTT circuit?
Thanks in advance!
Roger