This may be sacrilegious, but I've been using the UART ports for a long time as the comm interface between all the processors in my radio. You even could set it up as 485 multi-drop. I mainly use command/response type of protocol; the only information that is constantly sent is the S Meter value on a timer at about 10 times a sec. Unless tuning, then the frequency information is sent for each interrupt of the tuning knob. . I've used this concept for over 30 years in my professional career as UART has been around forever. It is inherently bi-directional with the current hardware implementation and processors have a very good interrupt system for this.? Of course, this idea won't pan out if you need to stream gobs of info. The newer implementation of the UART can go to over 1Mbaud.
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Russ
