Hardware Reference
In-Depth Information
away after soldering. Then, insert all of the push buttons in the marked button slots
(all the way flush with the board) and solder them in.
Next, solder in the potentiometer (it has three “legs”) in the slot marked Contrast,
and the MCP23017 i2c port expander chip gets soldered into the slot marked
(MCP23017). Just make sure you align the notch in the chip with the notch in the
silkscreened outline, or it will not work.
At this point, we recommend deviating from the Adafruit kit a bit. It comes with a
normal height header connector (looks like a black plastic rectangle with holes and
pins on the other side), which will work fine, but if you want to be able to connect other
devices through the LCD Pi Plate (specifically, the Pi Cobbler), you should buy one of
the extra-tall stacking headers. Either way, put the header in the underside of the
board so that the pins stick up through the top. The header is where it will connect to
the Raspberry Pi GPIO pins. Solder it in (on the top).
Then, stick the rubber bumper to the underside of the board, right above where you
soldered in the buttons, sitting flat, as close as you can get it to the buttons and the
left edge without overlapping or going off the board.
Break off a 16 pin length of the header pins (or 18, if you bought a different LCD that
requires more), and insert it into the top of the LCD Pi Plate with the long pins sticking
up. Put the LCD into position, setting into to the long header pins. Solder each of the
header pins on the underside of the board and on the top of the LCD.
At this point, it should be completely assembled (and sturdy). You can push it onto
your Raspberry Pi, inserting the GPIO pins into the connector so that it lines up neatly
on top of the Raspberry Pi.
Again, if any of these steps are unclear, the Adafruit online tutorial is excellent, so you
should refer to it if you get confused along the way.
Install Software to Control the LCD Pi Plate
Adafruit is also worthy of respect because it writes open source software to drive the
hardware that it sells. The LCD Pi Plate has a Python library written for it that you can
use to access and program the LCD and buttons. You can get a copy from their
GitHub
repository
, but we have also included a copy in the
GitHub repository for this topic
(along with some additional code that we wrote to monitor the IP address on the Pi).
Go ahead and clone our GitHub repository on your Raspberry Pi (if you haven't done
it already):
$ git clone https://github.com/spotrh/rpihacks
In order for any of this software to work, you need to enable the I2C support in the
Linux kernel. If you're using a custom kernel (on any Linux flavor), configured as de-
