I hemmed and hawed over splitting out the LCD from the board that came with the kit. It really is just a little more work to move the components to the new board, especially with the Eagle files provided by Adafruit. I didn't really want the reset and contrast control on the front panel, and thought it would be nice to re-arrange the layout of the control interface. Here's the existing board:
The Eagle files made it really simple; I just copied in the components to my main board file and started switching over the power symbols, and putting connection headers where needed. I went through each module of the circuit and made the necessary adjustments; here's the simplified user interface circuit:
Busses in Eagle can make this pretty simple, allowing you to focus on one part of the design without a mess of wires all over the place. Here, we split the connection to the LCD and use a bus to keep the module self contained:
Other components that needed to be placed included the Arduino itself, which will be mounted upside-down on the board against header pins, as well as the humidity sensor terminals, and the power block. Here's the first draft of the full schematic:
Next up will be designing and layout of the actual board itself, in preparation to etch and assemble.