As mentioned before, the LCD Plug will need to be redone. The MCP23008 chip pinout was completely wrong…
But hey, it does look nice, doesn’t it?
Here’s how it’s supposed to go on the back of any LCD with a standard 16-pin header:
The board can be mounted very close to the LCD because it uses SMD parts:
Alternately, it could be flipped over and mounted alongside the LCD.
Note how the solder pad configuration is on the other side, so it can be adjusted once mounted. Not included in this first prototype is a small trim pot to adjust the contrast level.
So the real LCD Plug will take a bit longer – hopefully the next board will be without these crazy mistakes…