@haas - I received my HaasTI ZigBee Switch yesterday. I decided to keep things as simple as possible for right now, so all I did was plug in power to the microUSB port on the board (i.e. no Arduino/UART Serial communications for right now.) I am happy to report that the board was discovered properly by my development Hubitat hub using the driver you linked above in the first post. I am able to control each of the 4 digital outputs without any issue. The two digital inputs worked fine, as well as the 4 analog inputs.
I have not monitored the UART pins yet for serial traffic, but so far, so good! Great job and very professional looking and built board.
If you are open to some enhancement on the Groovy Side, I will be creating a Composite Device Driver for this little board which will make it fit into the Standard Capabilities available on Hubitat (and SmartThings.) This will make it easy to treat each digital output as an independent "Switch" device, the 4 analog inputs as "Voltage" devices, and the two digital inputs as either "Contact Sensor" and/or "Button" devices.
Again - great work on this!!! Thank you!