Adafruit LCD shield + SparkFun LCD


Have a bit of what seems like a strange question to my newbie-to-Arduino mind, but I'll ask anyway, as I'm trying to get my project off of the ground and researching (==googling) hasn't yielded an answer yet.

I plan to use a 20x4 LCD character display in this project. I've looked at a few vendors and kinda like what Adafruit has to offer in general. For example, I have learned that the Adafruit 16x2 LCD shield can be used to drive the larger display, but that the buttons might be covered up. That's ok because I planned on wiring in buttons to an outside casing anyway. The Adafruit LCD shield:

It uses I2C, so only two pins needed from the Arduino. Cool. However in searching the website and asking Adafruit themselves, they have three basic variants of LCDs:

  1. White on blue (Standard LCD 20x4 + extras [white on blue] : ID 198 : $17.95 : Adafruit Industries, Unique & fun DIY electronics and kits)
  2. RGB backlight positive (RGB backlight positive LCD 20x4 + extras [black on RGB] : ID 499 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits)
  3. RGB backlight negative (RGB backlight negative LCD 20x4 + extras [RGB on black] : ID 498 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits)

However I was searching for a black-on-green LCD. I suppose that the 2nd option could be used but I'd prefer to just have a dedicated black-on-green LCD. I found one at SparkFun:

Both LCDs are HD44780 and appear to use the same number of pins (roughly). So could these two be used together (a SparkFun 20x4 LCD and the Adafruit LCD shield)? Adafruit seems to suggest that they could, but that they wouldn't support such a combination, and I understand that. I wished that they'd offer a dedicated black-on-green display, but they don't.

I did search to see if there was an equivalent SparkFun LCD shield, but wasn't able to find one. If I missed it, that would be a better option, so please let me know.

Anyway, thanks in advance.

There should be no problem with the LCD itself (pins 1-14). There could possibly be a problem with the backlight control since the backlight (pins 15 and 16 on most, pins 15 - 18 on the RGB) is not part of the LCD specification and they may not be wired similarly.


Edit: I do not have Eagle installed on my computer and Adafruit's schematic is in Eagle format. If you can come up with a PDF version I'll see if I can determine how versatile the backlight wiring may be.