LCDC: Keypad usage

   Keypad presses are handled through LCDC's Event section, as they are seen as triggers to initiate a specified action. But before we get into keypad events, you'll need to make sure your keypad is connected correctly and figure out what input it sends.

   The default keypad connector for the MX2 LCDs has 6 connectors, but the keypad connector on the LCD has 10. Looking in the manual, Matrix Orbital says that such a connector (one with less than 10 pins) should be centered on pins 6 and 7 of the keypad connector. Following this, I connected the keypad in such a way that there were 3 unconnected pins to the left of the connector (towards the side with the GPOs and power connector) and 1 unconnected pin on the right of the connector, towards the side where the USB connector sits. If you bought one of the MX2 LCDs that comes with a keypad installed in the drive bay faceplate, this should already be connected properly, but it doesn't hurt to check.

   After that's done, you'll need to figure out what input the keypad keys generate. To do this, if you're running any version of Windows, open up HyperTerminal. If you don't have it, you can download a free version of Hilgraeve's HyperTerminal here. Set up the connection so that the specified COM port is the one that your LCD is on, and set the BPS rate to 19200. Once connected, begin to hit the keys on your LCD's keypad and see what shows up on the HyperTerminal window, and take note. For me, this is what input each key generated:

Up: "K", Down: "L", Right: "F", Left: "R", F1: "Q", F2: "P", Enter: "J".

   Your keypad might vary depending on how you connected it and what type of keypad it is, but in any event you'll be able to get the input this way. Once this is done, you have the information necessary to begin making LCDC events that will respond to the keypad presses.

   Probably the easiest thing you'll want to assign to the keypad is the ability to scroll through the screens you've created in LCDC. The Right and Left arrow keys on the keypad seem logical enough for this, and to do this, create an event based on the "Sys>On Keypad Press" trigger. In the parameters field below, enter in the character that represents the Right Arrow, and in my case this was "F". Make sure to match the case of the character, as there is a functional difference between lower and upper case.

   Then for the action, select "Dsp>Skip Forward 1 Screen". Create a similar event for the Left keypad key, just changing the action to "Dsp>Skip Back 1 Screen", and you're done! With these keys now, you can go back and forth between screens, and won't have to wait for the duration of each screen to see the next when you need to view a particular screen, or if you missed a screen and need to go back to it.

The keypad connector.

Connecting to the keypad.

Keypad events.

   Another thing you can use the keypad for is to pause or stop on the current screen. For example, if you're reading a scrolling news feed using the RSS plugin, and need a little longer than the duration you specified in the Screen Builder to digest all of it, you can have LCDC stop at the screen until you tell it to go on. Doing this is easy - I've used my "F1" button for this, and you just need an event that specifies the keypad press relating to this button.

   Then assign an action of "Pause Display On/Off" to this event, and it's done. Pressing this button will pause the display at whatever screen it's currently on, allowing you whatever amount of time you need to read it, and then pressing it again will cause LCDC to resume the normal cycle of screens. Pretty handy, eh?

   But remember how we created an event to lock only to Winamp screens when Winamp was playing, and then configured LCDC to skip Winamp's screens when Winamp wasn't active? That's pretty handy, but sometimes you'll want to view other screens when Winamp is playing, or you'll want LCDC to resume it's normal cycle without you having to stop Winamp. With the keypad, this is easy as well. Just assign a button an action of "Dsp>Unlock from Group(s)" and that's that! You can always go back to the Winamp screen and pause the display there later, if you wish.

Pause/Unpause is very useful.

Unlock the LCD from Winamp even while it's playing.

Restarting the Backlight.

   The last thing I did was assign an action/parameter of "Dsp>Process Commands" / "BacklightOnOffAfter1Hour" to the "Enter" key. Thus, after the backlight automatically turned off 1 hour after starting LCDC, I could start it up again and have it stay on for another hour. This is a pretty nice combination of events, as it keeps the backlight off for extended periods of time when I'm not around, possibly lengthening its life, while still allowing me to turn it on when I need it without having to worry about turning it off manually.

   These are only the very basics of what you can do with the keypad. Using the Winamp plugin, you can use keypad presses to go to the next or previous track, and this combined with the variables available can making controlling Winamp from the LCD pretty sweet. You can also specify keys to adjust the contrast of the LCD, or the Backlight intensity as well. Heck, you can even close LCDC using a keypad event!

Shift enable keypad event.

Shift disable - note that the input character is lowercase.

   The last major concept with the Keypad is the shift ability. You need to assign an event to trigger shift states. When shift is enabled, the letters input from keypad presses are changed from upper to lower case. So, if the input from the Enter key were "J" without shift enabled, with shift enabled it would be "j". This is why case matters when you're specifying the parameter for a keypad press. You don't have to set a keypad key to be the shift toggle key - there is an event that triggers when you click the LCDC icon in the systray, and you could use that instead. By using the shift function you can double the uses for the keypad. For example, you could have the keys perform basic actions like Forward/Backward Screen, etc. when in the non-shift state, but have them perform Winamp commands like Next/Previous track when shift is enabled.

   An alternative is to use the Group or Screen-Specific Keypad press events. This way, keypad presses can perform different actions based on what screen or group of screens is showing on the LCD, so you could have the Up/Down buttons adjust volume (using the Multimedia LCDC plugin) while the left/right buttons made Winamp go to the previous/next track, but only when the Winamp screens were being displayed. And, if you configured the screens to only be displayed when Winamp was running, and made LCDC Lock to the Winamp group when Winamp was playing, this would be the ideal setup, as once Winamp stopped, LCDC would leave the Winamp group and the keypad buttons would revert to their default function events.

   As a little addendum to the keypad usage, I wanted to touch on how to reset the baud rate of the display using the manual override method specified in the manual. First, you'll need the program called "Display Tuner"; it's available on the Matrix Orbital CD. Next, after turning off the display you need to put a jumper on pins 6 and 7 of the keypad interface. (6 and 7 should be on the right side, towards the USB header.)

   Then, power up the display (which basically means plugging the USB cable into your computer as the MX2 receives both power and data over the USB interface. You can now remove the jumper, and open up the Display Tuner program, and use it to connect to the proper COM port. The baud rate should already have been reset to 19200 by now, but you can make sure by setting it to that value and clicking set, in the program. You should then turn off the display and then turn it back on. (Unplug, then re-connect.) The reason I have outlined this mundane procedure is that you may come across a case where your LCD just displays "garbage" characters after using some LCD output programs with it. If this ever should happen, as it did to me, simply follow this procedure and things will be back to normal.

GPO (General Purpose Output) Usage

   The MX2 has 6 GPOs, three of which are classified as "high power", while the other three are classified as "low power". These GPOs provide a power output source that can be controlled by the LCD through software, such as the LCDC software talked about above, so in this way you can use LCDC to effectively control the power output on these 6 GPOs, and with the proper parts and know-how, turn on/off fans or other electrical devices.

   Even better, you don't have to manually control the GPOs; just as we've done in the Events section above, you can configure the GPOs to turn on or off due to a specific trigger event. For example, when using the MBM5 plugin, you can setup an event that turns on a GPO that powers a fan when your case temperature reaches a certain point, and then only turn off that fan after the case temp. has fallen below another value. In this way, the MX2 can pretty much be a digital fan controller of sorts. GPO usage is another reason to get one of the MX2's that has a keypad, as you can use the keypad to manually control GPOs if you want.

6 rows of 2 pins (boxed in red) form the GPOs; blue-boxed connector is for an unmodified floppy power cable from your PSU. (Pic copyright Matrix-Orbital)

Setting up a GPO event.

GPO power states.

  In the above picture from the manual, you can see the block of pins that form the GPOs' connectors. From the top -> down are GPOs 1 -> 6. The positive lead is on the right side, towards the center of the PCB while the negative lead is on the outside. The top three (GPOs 1-3) are the low power GPOs; by default they each provide up to 20mA at 5V, and draw their power from the USB connection. This shouldn't be a problem if you plugged the MX2 into a power USB port, like one directly connected to your computer, and not one that's from an unpowered USB hub, as the LCD itself uses probably less than 200mA, and powered USB ports are spec'd to provide up to 500mA at 5V. These GPOs are perfect for powering an LED, as a lot of LEDs run at 5V. You could mount an LED somewhere on your case, and then create an event that triggered a GPO to supply power to the LED when, for example, your CPU's Heatsink's fan dropped below a certain level of RPMs.

   All you'd need to do is make sure the MBM5 LCDC plugin is active, and that MBM5 is correctly monitoring your CPU's fan speed. Then, create an event similar to the one in the above center pic, and set what you consider to be a low fan speed as the value instead of the 1500RPM I've used. The action tells the LCD to turn on and off power to the GPO 1 (Flash) so that the LED connected there will flash on/off - pretty neat stuff. There are other states that you can tell the GPO to be in as well, as you can see from the third picture above. On and off are self-explanatory, and so is flash. Strobe is like a faster flash; the GPO will turn off for a very short time, then turn off for a little longer, then turn on quickly again. The inverted modes flip the power states; so an inverted strobe means than an LED would stay on, and only briefly turn off before lighting up again, continuing the cycle. The inverted flash is hard to tell from the regular flash because the on/off times are almost the same. Toggle will switch between the on/off states, so if a GPO is on, this action will turn it off, and vice-versa. The toggle on/flash/off works in very much the same way, just cycling through three states. Cycle goes through all five states, in this order: on, flash, strobe, inverted strobe, inverted flash, and finally off before starting over again.

   Also, because of LCDC's robust way of handling events, you don't have to use one value that is the cut-off value; what I mean by this is that you don't have to set a GPO to turn on when a MBM5 temperature goes above 50C, and then have it go off when it falls below the same value of 50C. Instead, you might want the GPO to stay on once the temperature has reached a certain value, but not go off until the temperature falls below another, lower value. This is very effective if you're using the GPO to control a fan; you don't want the fan to stop just when the temperature reaches 49C; you probably want it to keep going until the temperature falls well below 50C. (This is just an example value of course.)

  While the first three (low-power) GPOs are useful for directly powering LEDs, the last (4-6) are labelled as high-power, and can be used to directly power a wider range of devices, even fans! But before you do that, there is some initial setup involved. The three high power GPOs can run at either 5V or 12V (Each providing 750mA either way), depending on the jumper position below the GPO block as seen in the leftmost above picture; with the jumper in the position seen above, the GPOs will run at 12V, ideal for fans; moved over to the left, the GPOs will run at 5V.

   Running the GPOs at 5V is not really recommended, as in this mode, each of the 3 GPOs draw power from the USB header, and since each GPO can provide up to 750mA, you can easily exceed the maximum current that a USB header can provide, possibly damaging your motherboard! (A single USB header can only provide 500mA.) Running the GPOs at 12V requires you to plug an unmodified floppy power cable into the LCD, at the connector boxed in blue in the picture above. This way, the high power GPOs draw current from your PSU's 12V source, and they don't put your USB header at risk from overdrawing current. Note that you only need to plug in a floppy power cable if you plan on using these high power GPOs in 12V mode; it's not necessary for normal operation of the LCD as it draws power from the USB header.

   With each of these GPOs providing up to 750mA at 12V, you can run most types of case fans off a GPO. There is something you will want to consider though; you probably should not just hook a case fan up directly. Instead, you need to clamp the circuit using a diode and a capacitor; Matrix Orbital makes this clear in their manual but it can be overlooked. The reason for this is that when power is turned off to a fan, the fan will continue to spin because of its momentum; because the magnets involved in the electrical motor will be still moving relative to the wiring in the fan, a current can be induced in the circuit leading back to the GPO, possible causing damage. All of this will of course depend on the fan/motor type, but it's best to be safe. In the diagram below, you can see the two parts you'll need, the diode and a capacitor rated between 10-100 microfarads. Note that in the picture below, the load device is a relay; it's suggested that you clamp the circuit whenever you're powering an electromechanical device, such as a relay, fan, or other device that involves magnets, as whenever they're present harmful induction can occur after the device is switched off.

Properly running a device off of a GPO.
(Pic copyright Matrix Orbital)

  In any event, one can easily see how nice it would be to hook up a case fan to the LCD, while using LCDC to control its actions. You could have the fan turn on automatically when your case reaches a certain temperature (as described above), or you could use the LCD's keypad or some other Event trigger to turn on the fan manually; the options are very much wide and varied. If you need to power other devices that draw more current than even the high power GPOs can provide, you can always use a relay; 5V and 12V relays are both abundantly available, and thus you won't have trouble finding them. You could always use a 5V relay with one of the low power GPOs to turn on other devices as well.

Conclusion

   An LCD is not just a pretty little thing that adorns your case like a jewel; instead it's a pretty little thing that provides many useful features and performs many functions. In addition to just displaying information, the LCDC software transforms the MX2 LCD from Matrix Orbital into a fully featured component of your PC, making it not just some subordinate device, but one that can be used to respond to changes in your system by automatically. The key is spending time playing with LCDC to learn how to do new things. I'll be the first to admit that this guide provides perhaps just beyond the basics of LCDC usage; with time and effort you'll be creating your own personal setup to suit your system's needs. LCDC is like a sturdy foundation upon which a masterpiece of construction can be built, with the wide variety of plugins acting like essential construction tools. This, perhaps, is LCDC's strongest feature - the multiple plugins don't just add new features, but add the ability to work with one another, and in this way, LCDC is more than the sum of its parts. I hope you've enjoyed this guide, and don't be afraid to give me a shout if you have a question/comment about, or have found an error in, this guide.

   Lastly, thanks goes out to Henry of Matrix Orbital for providing the LCDs used in this guide!