on your power supply ... I've found that, in some cases, the load on the contrast pin is more than I initially thought the entire LCD module should use.

Further, it won't make for a very good looking device unless you use two 8-character displays, which are not common. That will take 15 signals, since you need 13 common signals and an "E" signal for each. It's certainly easier to manage.

Often, they're hard to read and the characters are too small. (Don't overlook the programmable character set, since that might be larger with a little creative help.) Without a backlight, it will be hard to read, especially in bright sunlight, as at the park.

I was kind-of wanting to see the finished product. Coding it should take at most a day, debugging, at most a week, and thorough testing no more than a year. What I had in mind was a nice, WW-II-era-looking thing done in beautifully finished teak, walnut, or mahogany, with classic knobs on the switches and, wrinkle-finished black metal bezels around the half-inch-tall 7-segment displays. All the electronics should be entirely happy to operate from 4.5-volt batteries, so there'd be no loss in a regulator. The pushbuttons would be on a longish metal bar with a fulcrum to be inside the box, with an optical interrupter used to provide bounce-free indication of which button was last pushed.

Now, you may have had something else in mind ... it is, after all, YOUR project.

RE