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Guide: Character LCD Module

Discussion in 'Modding' started by RObErT_RaTh, Aug 31, 2005.

  1. RObErT_RaTh

    RObErT_RaTh Member

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    Character LCD Mod w/Backlight
    By RObErT_RaTh

    Disclaimer: I take no responsibility for any damages caused to property or injuries to yourself or others through performing this mod. You attempt it at your own risk.

    This guide will hopefully help you to create a functioning Character LCD readout for your computer. When we are finished it will be able to display system temps, voltages, fan speeds, winamp song info, date/time, your own text and many other things.

    Here are the parts you will need for performing this mod with complete functionality:

    -An Alphanumeric Character LCD with a HD44780 or compatible controller (Max. 4x40) ~$15-30
    -Spare male DB25 parallel printer cable or 10 core cable of some kind ~$5
    -25 pin D-Type Solder Male Plug $1.40
    -25 pin D-Type Backshell $1.80
    -10k Ohm (Linear) Potentiometer $1.75
    -100 Ohm Trimpot $0.75
    -Knob to suit 10k Ohm Pot (personal preference) ~$1.50
    -25 Way SIL Snapoff Header Pins $0.53
    -Old floppy drive cable or just the connector on the end $1.50 for connector
    -Molex Y-Splitter $1.50
    -Some hookup wire

    [​IMG][​IMG]
    (In the pic you can also see some SIL IC socket pins which I THOUGHT the header pins would fit into :? I didn't try it in the store and was upset when I went home and they didn't fit so that's why I resorted to butchering my floppy drive cable ;))

    Total minimum cost: $28.23 (Much cheaper than a Matrix Oribital ;))

    Tool and other things required for the mod:
    -Soldering Iron and Solder
    -Electrical tape
    -Screwdriver
    -Wire Cutters
    -Wire Strippers
    -Tweezers

    First thing you want to do is get some header pins on that LCD of yours. I wanted to use header pins and a plug so that I could easily work with the LCD and not have to drag a heavy cable around and risk the wires coming loose. Most people wire straight to the board and there’s nothing wrong with that, I just like a little flexibility.

    You’ll need to figure out which pins we will be using for data transmission. Here is a pinout table to help:

    [​IMG]

    Looking at the above table you can see that we need to wire pins 4, and 6 through 14 to the parallel port. These are the only points on the LCD module that we want to have header pins. Look on your LCD module and identify pin 1 and work your way along removing some of the header pins for where they are not required. Once you’ve done that solder the header pins onto the board. Make sure the tall part of the pin is sticking out of the rear of the board. Solder the first pin and then the last, resolder and straighten if need to then solder the rest.

    [​IMG][​IMG]
     
    Last edited: Aug 31, 2005
  2. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Now we have our header pins in place the next thing we want to do is get our old printer cable and get rid of that connector on both ends. You can choose to leave one of the connectors on and discover the pinout for yourself so you don’t have to buy the male solder plug and backshell but I just found it easier this way. Once you’ve done that, separate 10 different coloured wires from the rest (we only require 10 wires for data transmission). Tape off and cut off the other wires. I left 12 and the bare wire just in case I forgot something ;)

    [​IMG][​IMG]

    Now you’ve done that to both ends (if you didn’t want to keep a connector) strip the wires on one end but leave the wires at the other end shielded. Grab your floppy drive cable or suitable IDC connector and unlock the connector. Decide if you are going to use the top or bottom row of the connector and push your wires onto the little self cutting holding things. I used a pair of tweezers to help push them on. Be sure to line them up with the correct header pins on your LCD. Once you’ve pushed them on, chop off the tops so there are no messy bits and then lock/crimp the connector together. Try the plug on your header pins and make sure all wires are in the correct spot and line up.

    [​IMG][​IMG]
     
  3. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Now get the other end of cable that we stripped and start soldering it to the correct pins on the male DB25 solder plug. I have included a diagram that shows the pins looking INTO the front of the connector (the part that actually plugs into your comp). It also helps if you fill the little tubes with a bit of solder first and tin the ends of your wires before soldering them. The wire insulation should be just at the end of each little solder tube, there shouldn’t be any exposed wire. Also remeber you are now looking at the plug from behind so the pin numbers are now mirrored ;) Screw the bracket onto the cable and mount the connector inside it’s backshell. You should now have your completed data transmission cable ready to go.

    [​IMG][​IMG][​IMG][​IMG]
    [​IMG][​IMG]

    Now let’s go back to the LCD module. This thing is gonna need some power so get your Molex Y-Splitter and cut off the second female connector. Here is a picture of what we should have connected to help you out.

    [​IMG]

    We only need +5V (your LCD ‘may’ be different) so cut the paired black and yellow wire to the main connector (cut very close so we don’t get any shorts and possibly cover with heatshrink) so now you have the splitter and just a black and red cable coming off. Wire up the cable to the LCD, red is +ve 5V and black is ground. Solder the red wire to Pin 2 of the LCD and the black wire to Pin 1.

    Next we need to connect up our 10k Ohm potentiometer for contrast control. Solder some wires to it and then follow the above diagram for connecting the other ends to the actual LCD module. The centre lead of the pot should go to Pin 3 on the LCD and one side can go to our +5V supply and the other to ground.

    And finally we can connect up some power to our backlight and put in a 100 Ohm trimpot so we can control its intensity. Once again follow the schematic diagram to see where things should go. Centre lead of the trimpot should go to the –ve Cathode for the backlight and solder one of the side leads to ground. If you also want to put in a switch like I did then put it between the side pin of the trimpot and ground. When I first hooked it up I didn’t put in the trimpot and just gave it the full 5V. Little did I know the normal operating voltage for my LCD’s backlight was 4.1V and max 4.4V  The screen began to go dark in the middle and the light was more yellow than green. It took me awhile to figure out what was going on so just be careful and consult your spec sheet for your specific LCD before wiring it up ;)

    [​IMG][​IMG]
     
    Last edited: Sep 1, 2005
  4. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Now I hope you haven’t forgotten about Pin 5 on the LCD and the fact that it needs to be connected to ground? Cut your self a small piece of shielded wire and strip the ends and solder Pin 5 of the LCD to ground.

    Congratulations all of the wiring should now be finished! But that’s only half of it, we need to hook this up to your computer and make sure it doesn’t blow anything up ;) Plug in your data cable and hook it up to your PC and plug in the molex power connector and turn on your computer. It should display 1st line as all filled in characters and second line all blank and then repeats this pattern for other lines after that. If you are not seeing this then adjust your contrast and backlight brightness and if still nothing or you see something else then turn it off and unplug it because you have done something wrong. Go back and re-check ALL your wiring.

    [​IMG]

    If all went well you can install the same program as me, JALCDS, which can be found at http://www.jalcds.de/

    It’s pretty self explanatory, feel free to mess around and display whatever you want. I hope you found this guide helpful and your LCD will be the star attraction at any LAN party amongst your mates ;)

    [​IMG]

    PS, this is how NOT to wire an LCD. I prey none of you EVER do this!

    [​IMG][​IMG][​IMG][​IMG]
     
    Last edited: Sep 1, 2005
  5. MWP

    MWP Member

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  6. OP
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    RObErT_RaTh

    RObErT_RaTh Member

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    Mine actually utilises the backlight and contrast controls and doesn't wire straight to the board. Anyways, I felt like doing one so I did it :)
     
    Last edited: Sep 1, 2005
  7. yon2004

    yon2004 Member

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    good work i like yours better :)
    i alredy tryed mine onece and it dident work :tired:
     
  8. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Thanks mate :)

    Following this guide or one done previously?
     
  9. Jewsian

    Jewsian (Banned or Deleted)

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  10. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Thanks mate :) Would be great if it was added to that other thread. Do I just post a link or does someone else need to do something?
     
  11. Jewsian

    Jewsian (Banned or Deleted)

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    From the looks of it I would think you just post it up
     
  12. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    Consider it done ;)
     
  13. TRG.dOinK

    TRG.dOinK Member

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    hehehe good guide

    ive been programming my 8051 microprocessor to my LCD screen in assembly using 4 Bit mode, sending the upper then the lower nibbles :) My lcd doesnt have backlight though :(

    Here is a good website to learn manually how to use a LCD screen.
    www.geocities.com/dinceraydin/djlcdsim/djlcdsim.html

    Here are the LCD Commands.
    [​IMG]
     
    Last edited: Sep 2, 2005
  14. Pyro

    Pyro Member

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    Interesting d0ink, i've been doing some assembly at Uni along with VHDL, its cool stuff :)
     
  15. nudge

    nudge Member

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    I recently programmed up one of those JayCar 2*16 LCD screens on a Texas Instruments TMS320F2812 DSP chip, getting the timing right was the biggest issue.

    Second was finding the correct datasheet -- we almost blew one up because we had the wrong datasheet and the Vdd/Gnd pinout was backwards! So if youre connecting up a JayCar LCD, make *sure* you verify the correct pinouts.

    This was part of the FEC 2005 comp. which we won (click sig!). We actually designed and built our own custom DSP controller and LCD daughterboards.

    [​IMG]
    Click to view full-sized image!
    Hosted by UGBox Image Store

    Nice guide by the way.
     
    Last edited: Sep 4, 2005
  16. TRG.dOinK

    TRG.dOinK Member

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    Yep i have been doing VHDL and ABEL.. but its hard to remember stuff because everything is so quick. Last thing we did in VHDL was traffic lights with a button for crossing using ispLSI 1016.

    Assembly is alright when things work and you know what your doing otherwise its headaches. I've still got more to learn with lcds though.
     
  17. petercr

    petercr Member

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    An alternative to using a floppy drive connector (especially if you're running the display external to your case) is to use the power that a USB port can output. You can buy a 3m USB cable from DSE for $5 (cat# XH4299) and chop off one end and use the black and red wires. USB ports are good for (in theory) up to 500mA of current.

    (and even add your choice of sleeving)
     
  18. OP
    OP
    RObErT_RaTh

    RObErT_RaTh Member

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    That's a great idea, I though about it but its only really beneficial if you plan to mount it externally and I was also unsure if I was putting too much load on the USB power.
     
  19. petercr

    petercr Member

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    But you still need to work out a way to get the parallel port cable insde... The current draw by the display itself is only about 10mA, it's the backlight that would draw most of the current - my 20x4 draws about 400mA - which is still within limits of the USB spec.
     
  20. tzortst

    tzortst Member

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    My lcds came today :)

    the graphics one is huge! Just went down to Dick Smith also, and bought some of those header pins/plugs i think they would work better then using an old IDE cable etc...

    here are some pics

    http://tzortst.com/imagestore/lcd1.jpg
    http://tzortst.com/imagestore/header.jpg

    Decided i will mount the graphics one in a seperate case, but i need to work out a power supply for it first :| -20V not fun :(
     

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