LEDs on Tait 8105 with Advanced Digital Modem

Rick N9UMJ was so kind as to send me a Tait 8105 VHF mobile radio with an Advanced Digital Modem attached for experimentation purposes. It could serve as a MMDVM high power hot spot. But as HamRadio in Friedrichshafen is due I decided to make it an APRS tracker with a homebrew SVX_Hat board mounted on a Raspberry Pi. For optical feedback of the PTT state I configured the front LEDs to reflect the PTT state.

Tait 8105 with Advanced Digital Modem

The LEDs are obviously wired to the GPIO pins of the radio. The relevant GPIOs are 2, 3 and 5. I configured them in the codeplug as shown:

GPIO Configuration for Front LEDs

You have to set the GPIOs as outputs with active high state. GPIO5 is wired to the TX LED. I set this to “Radio Transmission Status” to show the PTT state. GPIO3 is wired to the DCD LED which is showing the squelch state with setting “Busy Status”. GPIO2 is the RXA LED which I currrently do not use.