Introduction
I am sure that many of you
already own or have seen PC LCD displays before. There is nothing
like a bright multi-line display spewing a plethora of information from
the front panel of a modded case. Thus, I was very excited to
find out that Matrix Orbital would be sending me one of their MX212
displays for review. What I didn't know was the wide versatility
of the device. The MX212 comes with everything you need to tailor the
panel for your particular application. Included in the package is
the 20 character by 2 line display which mounts in a standard 5-1/4"
drive bay, an attached "external" USB A-B cable, a built-in 7-key
keypad, mounting hardware, a driver disk, and a full version of
LCDC - LCD Control Software. Along
with the standard package, Matrix Orbital also sent two temperature
sensors, an internal USB cable, and The Indicator - LED Bus. All
of which are optional accessories.
Bells, Whistles, and Blow-Horns
The front panel of the MX2 series of displays is pretty straight
forward. There are four directional pads, an F1, F2, and Enter
key. All of these keys can be configured through software to
control numerous functions. You will notice in the screenshot
below an LCDproc Server running. LCDproc is a Linux LCD control
program which I will get into a little later.
The image below was hijacked from the
Matrix Orbital Technical Manual and slightly modified. This is
the back panel of the LCD and is the heart of the MX212.
Clockwise from left to right you will first see the Fan Headers.
In order to use these "high power" devices, the High Power Select
jumper must be set to HP. You will also have to connect a
standard floppy power cable to the High Power Input connector.
The Fan Headers can sense RPM speed as well as doing one more
interesting thing. They also act as high power GPOs (General
Purpose Outputs) 1, 2, and 3. Delivering 1A @ 12V, they can
easily be used to
trigger a relay to control electronic devices, high power switches,
etc. We will show you
how this works later in the article. It can be very useful.
Next to the Fan Headers are the low power GPOs 4, 5, and 6. These
GPOs are
mainly used for LEDs as they can only deliver 25ma @ 5V. Usually,
not enough for any type of decent sized relay. This is where The
Indicator - LED Bus connects.
The Rx / Tx LED Headers can be used to display traffic to the display
using LEDs. This header can also be used to connect directly to a
serial port. Though, soldered jumpers will need to be changed on
the board and the USB will need to be disconnected. This header
is not usually used.
The USB connector is for a standard USB cable while the Alternate USB
header is for using an internal USB cable. The Keypad connectors
come with the LCD/Keypad ribbon pre-attached and usually aren't used
for anything else.
The 1-Wire bus is used to connect temperature sensors. While
there are only four headers on the board, it supports up to a total of
32 sensors! Yes, I said 32! This is because the sensors use an
addressing scheme by Dallas Semiconductors
(The Dallas 1-Wire Bus) allowing
them to coexist on the same bus.
