[Mechanical keyboards] krbjmpr:
Well, its very ugly, but got the usb switch encoder, keypads, otg usb hub, and a *lot* of wires put into the vehicle this morning. Wanted to play with it on the way to work. Of course, only while am at stop signs and lights. I am positive drivers behind me were somewhat annoyed.

Talk about a difference of night and day compared to the bluetooth media pad I was using! Absolutely zero delay when switching back and forth between apps, pushing pause while playing, next track, previous track, etc. I have 12 switches to play with, and oddly, was still concerned about needing more. Then I discovered that I can layer activities. So...

Button1: Short Press give directions to Home, Double Press goes to Work, Long press opens Maps 'normally'.

Button2: Spotify

Button3: TorquePro

Button4: Not assigned yet, but will probably be Task Manager on long press, and next task with short press. Will have to set some kind of delay in constraints. Not sure how to do that, yet. Or, Mute and System-wide Pause.

Button5: Volume Up, and without any notification / popup window. Sweet!

Button6: Volume Down, again, no popup. Thought about doubling up as double press on Button5, but I can see getting into an endless loop.

Button7: Play/Pause

Button8: Next Track with short press, Long Press takes back to previous track. At least it should, most of time it just goes to beginning of current track.

Buttons9-12: Not sure yet. Probably give at least Vol +/- and play/pause to front seat passenger. Should help conversation flow more fluidly.

Oh, it also looks like Key Mapper is able to start activities, both directly and via shortcut.

The keypads that I paid (not so) dearly for don't feel like they are going to last very long. At the very least, need to find a way to illuminate the keypad, perhaps even with printed icons, to help minimize pressing on edges of each button.

I haven't played with the 2nd joystick yet either. That will be 4 more buttons to play with as well. Also thinking that using a D-Pad type of keypad will be more optimal for controlling media.

Just occurred to me that I might be able to tie this into another project nicely. I have been working on incorporating a frame grabber into the fray. As it is, the frame grabber can only send 1 video feed to the system, but the video switcher can send a single camera, or all cameras. So, reverse lights come on, and rear view camera displays on tablet. Turn Signal (with filtering for flashes?) turns on camera on appropriate side. Horn connects to video switcher app, via encoder, changing mode to all cameras so all content is recorded.

Almost forgot. Using the current OTG USB hub with charge capability yields the tablet "Charging Slowly" and I should "Check your cables and adapter". When left for work, tablet was at 100% (actually 85% since I limit battery charge). No drain below 100% on way to work. On way home, same apps were running (Maps, Torque, Spotify as well as near-continual playing with buttons. Tablet never did drop to below 100%. So, at least for my implementation, slow charging is still keeping up with power demand by tablet. Incidentally, tablet was in "Day Mode" on way to work, "Night Mode" on way back. LTE in use (streaming Spotify) as well.

Just found an app (free! but at what cost?) that is able to control 8 relays via USB. And can do inputs too.