The component count is as low as possible. You may choose to take the supply from another source than the FT8x7 ACC port, such as a dedicated 9V battery.
You cannot leave out the two N.O. pushbuttons "[Up]" and "[Enter]" ("[Next]" on the diagram), but you can skip the LCD backlight control (mind the total supply current does not exceed 100mA, better less!).
This circuit is also the base for the keypad+display device I am still working on. The keyboard extension chip (PCF8574) will be connected to pins 4-5-6, so leave room for it on your board... in case you'll be interested in that device too.
"Release Candidate 1" ("RC1") firmware is available on request, until I publish it on my website.
Testers needed.
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