So about to buy parts for a Cub Scout model rocket launch control system! Yay!!!
It is made of multiple boxes, each with a big 12V battery and an Arduino, networked together. At the launch pads, each Pad Box needs to power both the static 5V control logic AND 12V through relays to between one and eight model rocket igniters. Although the RSO has the Master Arm, _each_ Scout/LCO has their own Launch Button.
The big difference between systems I have seen elsewhere versus our needs: it seems almost all of the other multiple-pad controllers I've seen--one-person launches for all. But we want to continue to allow each Cub Scout (after the RSO arms) to control their own individual launch buttons. Most Scouts comply with the shared countdown & "drag race." However there are often Scouts who want to "confirm their own control" or "call attention to themselves" by launching early or late! A little early or late, no problem....these "control freaks" may become real rocketeers someday! (But we do want the RSO's master-arm to keep it within bounds).
So all of the individual launch buttons are merely gathered as inputs to the RSO's Arduino control. Only when the Pad Boxes have their local power turned on do the Arduinos (or anything else) come on. Only when the RSO pushes the Master Arm do the Pad Boxes' Arduinos get commanded to power on the relay boards. Similarly, only when the RSO's countdown clock enables the two second window, then do the collection of launch button signals get forwarded to the Pad Boxes. So remove any of FIVE keys or momentary buttons, or the control logic, then NOTHING happens. Add in extra distance, buzzers, strobe lights, "Apollo-style" countdown/message display, Scouts launching from under a tent, "peanut gallery" watching/waiting under another tent... Well you see we take safety _very_seriously_ indeed!
"Two heads are better than one..." So here it is, please give me your recommendations... Three Arduinos of some model(s), RS485 interfaces, driver/relay boards, all of it is open to suggestions. "Not too proud to beg." Thanks in advance.