Here are some projects I've been working on.
This project is for a fully isolated rig interface unit for Echolink, FreeDV/Codec2 and other digital modes. It requires just a single USB cable from the PC to the interface and a single data cable from the interface to the data port which is available on most modern rigs. An optional second cable can be connected to the radio for CI-V/CAT control.
This project is a serial IO / breakout daughter-board for the Rasberry Pi that includes a 7-30v wide range power supply, RS-232 compliant interface and 6 GPIO signal pins with 5v level shifter.