Android for monitor/control applications?
I built a few monitor/control systems for use around the house. For historical reasons, they're PALM 3C for high level functions like user interface, math and storage. Serial interface to a microcontroller for raw data acquisition and real hardware for the actual hardware interface and stuff that is too fast for the microcontroller.
As you can imagine, running 24/7, a PALM isn't gonna last more than a few decades. The pile of dead PALM 3Cs is becoming worrisome.
Serial ports have gone away. I experimented with Bluetooth to serial dongles on the hardware end and Bluetooth SPP on the PDA end. That works, but those PDAs are also EOL. Same problem with IR interfaces.
I've been playing with App Inventor. The jigsaw puzzle analogy makes it easy to cobble together the control/interface part. My concern is the real-time aspects of the process. Anything truly real-time will have to be in the hardware outside the phone. But there are real-time-adjacent issues. App Inventor doesn't seem to have any facilities for atomic functions.
Previously, there wasn't much going on in a PDA.
With an Android phone, there's a LOT of stuff going on. There's a lot of hidden magic between the user and what can go in/out the Bluetooth. That might have significant implications for the size of the data buffers on the hardware end.
While I wouldn't expect precision timing, my app might malfunction if the processor went away for a long time trying to find a cell site or initialize the GPS or overlay an advertisement across the screen. We seem to have less and less control over the crap foisted on us with every Android release.
What's reasonable for easily developed real-time-adjacent apps?
I consider rooting the phone to be VERY undesirable.
There's a lot written about real-time Android. That's not what I'm considering. I'm interested in thoughts/experiences using a standard PHONE Android as a quick and dirty monitor/control interface.