Photos:
Quick Keypad for writing software
Running in the house.
I really should have etched a board for this.
Schematic, quick and dirty.
The actual keypad it's wired to.
I had some shots of the board before I soldered the nano on it, so you could see the rest of the circuit, but I can't seem to find them.
The screw posts were mainly for testing, I wanted to solder my connections in permanently (connected to car with waterproof plugs) but I'm not sure if I'll bother to remove them when I install. Anyone think they'll loosen and let go with time?
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Also, as to not drain my car battery, I wanted to make it as low powered as possible. I removed the power LED, but not sure how else to lower power. It has to be available all the time, so the powered down modes of the chip wouldn't seem applicable. It's pretty low power now, so I suppose I shouldn't worry about it.