This module provides a breakout from a Yaesu CT-M11 cable to a Y1-pinout headset jack and a standard serial GPS.
For an absolutely simplified GPS-only version of this project, see the writeup linked here. As the basic version only requires 3 components, a pcb would be overkill.
But for those wanting a robust implementation and to use the headset without excessive noise artifacts from the GPS module, this version is designed to de-power the GPS module during headset TX to inhibit noise in the transmission. Additionally, the GPS can be de-powered when using as a headset adaptor.
Finally, the Mic line is connected to the DAC and the speaker line is connected to the ADC, hence there's some opportunities to code AFSK or other interfaces in the MCU. The USB port on the MCU can be used as a serial interface giving further opportunities for device hacking.
The full construction details are available here.