Are you still actively working on and supporting the Propeller HAT for the Raspberry Pi?
I think this HAT would lend itself nicely as a UART expander easily handling 7 ports. Each port would run in its own cog on the Propeller with cog 0 acting as the conduit to the RPi.
The Propeller has lots of RAM so could buffer a few kB per port making it easy for the RPi to wonder off and do other things and not have to worry about missing an incoming TX from a device.
I have been tinkering with these Propeller chips as a hobbyist for a few years but find myself wanting to get above its “bare metal” programming limitations especially when it comes to using it as a web server. Hence my interest in the RPi. I just ordered my first Pi but already am a bit stumped on how to go about hooking up my RS232 weather station and my Xbee RF module as both need UART and the RPi 3 has but one UART port. I would also like to add a few other devices that utilize UART for communication.
Do you think the Propeller HAT is a good choice for this or are there other HATs out there that already handle this UART expansion function?