LCD's and VFD's - The ultimate FAQ. Since this is a FAQ thread, posts that are not FAQs with answers will be deleted. If you have a question not covered here, post in the main Electronics forum, people are far more likely to read it. --your moderators What is an LCD? {param} LCD stands for Liquid Crystal Display. An LCD is a passive device, i.e. it doesn't actually produce any light, it simply alters the light travelling through it. With a voltage applied to it the liquid crystal polarises transmitted light in a different direction to when no voltage is applied (explanation here). A polarising filter in front of the display then blocks one of the two polarisations (i.e. the areas in which a voltage was applied or the ones where no voltage was applied) and therefore in some areas of the screen appear 'black', this effect is used to draw the characters and graphics displayed by an LCD. Almost all LCD's have a strong light source built in behind a glass panel (which contains the liquid crystal), this ensures that the areas of light and dark on the screen (dictated by the areas on the liquid crystal panel across which a voltage is applied) have good contrast. Displays with no backlights that rely solely on the light incident on the LCD panel cannot be used in low light conditions. What is a VFD? {param} VFD stands for Vacuum Florescent Display. Unlike an LCD a VFD is an active device; it makes its own light. It does this in exactly the same way as a CRT monitor or television, by accelerating electrons at a phosphor target from a hot element. A very well written guide explaining how this principle is applied to make a whole display can be found here. What are they used for? In general they are used to relieve some of the displaying load from your monitor, showing everything from system stats to current song playing and game stats. They can also be used as monitor replacements in mp3 boxes for example. There are two main ways of interfacing an LCD with your computer Serial and Parallel. A serial display is normally a parallel display with a serial controller bolted on... Alphanumeric and graphic? An alphanumeric display can only display characters (normally in 5x7 pixel blocks at specific locations on the screen). Screen size is measured by the number of characters the display can fit on one line and the number of lines in can display, e.g. 20x2 (20 characters per line and 2 lines). 16x2, 20x2, 24x2, 20x4, 4x20 and 4x40 are the most common sizes available. Graphic displays consist of an array of pixels which can be controlled at whim to display anything. 5x7 is the 'normal' font size; hence a 122x32 display is the graphic equivalent of a character 20x4. Serial and parallel LCD's you say, so what's the difference? Serial displays (RS232, SPI, TTL, USB, I2c,RS485... - with a little bit of wiring you can interface all of the following with an RS232 or USB port), they generally enjoy the best software support, are easy to interface with, allow for long data cables. The disadvantage of serial controllers is the interface speed, which isn't enough for full screen bit-map animations at any reasonable resolution. For character only (alphanumeric) displays the following serial controllers are the most common: -Matrix Orbital (RS232/I2C). There are quite a few different MO serial controllers in general they have; decent speeds (19.2Kbps is standard - which is about right for a 4x40 or smaller display), keypad support (allows momentary switches/keypad units to be attached to the LCD to control software (e.g. WinAmp), GPO's (General Purpose Outputs - basically driver controlled switches, so you can use you LCD to control your case fans or lights), software contrast control (useful for fading into screens, but a little pointless generally), software backlight control, 8 custom chars, custom boot screens on some displays, wide voltage input as an option (due to a silly power connector design normal voltage displays are easy to destroy). An LCD is only as good as it's software support and thankfully software support for all Matrix Orbital LCD's is good, support software is listed later on - try the software out before you buy! Buy from www.matrixorbital.com or http://www.hvwtech.com/ for a copy-cat controller. -Crystalfontz (RS232). A few diff types of controller here, their newest (the 633) is impressive but needs more software support. In general CF series boards (v2.0) are capable of, good speeds (up to 19.2Kbps), custom characters, contrast memory, large character sets, semi-graphic support for smooth scrolling and probably some small features I've missed (the 633 can PWM control fans and have temperature sensors added to it!). On the software front the CF display fairs well, some major pieces of LCD software work with this controller. Buy from www.crystalfontz.com. -Seetron (RS232) (Scott Edwards Electronics). The controllers vary depending on LCD size but in general they're very primitive. They feature below average speeds (9.6Kbps max I think, fine for 2x20 or smaller), standard character sets and on board contrast control (nice for permanently setting the contrast). The seetron controller can be made to work with LCDCenter, Driver and maybe LCDC - though functions are limited. Buy from http://www.milinst.com/ or http://www.seetron.com/. -Wirz (RS232). Very like Seetron, buy from http://www.wirz.com/ -Others (inc. in-built controllers). Most other serial controllers are fairly simple (and are often very similar to Seetron's). Exceptions to this rule are inbuilt controllers, like the one made by Noritake which is feature packed (in capable of great speeds and have 8 I/O's which can be used in the same way as GPO's or keypad interfaces). For character only (alphanumeric) displays 99% with parallel interfaces follow a single standard. They're nearly all HD44780 compatible (for 4x20 character displays or smaller). With parallel displays almost everything is done at the PC end which makes development more difficult, though theoretically you can do anything with a parallel LCD. They are very fast, with tops speeds of 115Kbps and normally have an inbuilt character set allowing for 8 custom characters. Software support is hopeless if you choose a display that doesn't use a HD44780 or compatible controller, but thankfully most do. For graphic displays the controller situation is a little different. Quite a few have serial interfaces which makes controlling them easy, but rules out full screen bitmap animation. On the parallel front the controllers vary wildly though we're starting to see some support appear. A closer look at some of the options: -Noritake (RS232, SPI, async, TTL and parallel). Their serial controller is pretty advanced and very easy to use, more info in this review - there's good support for this controller. Their parallel controller is also very nice, though software support for it isn't great (see later). Find Noritake here. -Matrix Orbital (RS232, I2C). Matrix Orbital do a range of graphical displays which have a similar feature list to their alphanumeric displays. They have font and image memory and support features like hardware scrolling. Find Matrix Orbital here. -Toshiba's T6963C controller and other large graphic controllers (parallel). There is now beginning to be some software written for some of the larger graphicals. The Toshiba T6963C controller is commonly seen on 240x64 and 240x128 displays and a couple programs will support this chipset (see later). These are relatively cheap displays, and very nice they are but they're nearly all green). Before you buy a large graphic display make sure you know how to wire it up and that it's controller has some software support, if it doesn't the display you've bought will be as useful as a chocolate fire guard. So how do I wire these up? Connecting a serial display is invariably as simple as plugging in a 1-9 wire pre-made serial cable and a power cable. With parallel displays you're probably going to need to get your hands dirty. I wouldn't recommend attempting to wire a parallel display if you're no good at soldering. Good wiring guides for HD44780 compatible LCD's can be found, http://www.icehw.net/article.asp?id=104 - a very comprehensive write-up. http://www.myrolypoly.com/lcd_project/lcd_project.html - (added 1/1/03) A comprehensive walkthrough by forum member ugly0900. http://www.geocities.com/ResearchTriangle/1495/ee_lcd.html (allows for variable contrast and backlight brightness) http://www.overclockers.com.au/techstuff/a_diy_lcd/ - (nice pics but no backlight. Don't hack the end off a print cable and expect the coloured wires to correspond to the same pins as the ones in this article. Sounds like an obvious thing to say, but it has caught a fair few people out). http://www.icehw.net/article.asp?id=99 (fantastic! lol) - for an LCD compatible VFD. http://www.theddrzone.com/review.php?category=112&id=146 - Nice and simple // wiring guide, Australian based 'where to buy' links.
I've heard that it's possible to invert LCD's and change the colour of them, is this true? To invert your LCD here's a quick guide from Linear :: This voids your warranty. So make sure you want it bad enough. The metal bezel that holds the LCD onto the board needs to be removed. To do this, get needle nose pliers between the boards and twists the metal clips so that they are aligned with the slots in the board. There are six or eight of them, and they all need to be in line with their slots. Then the metal bezel can be removed (and polished, painted, etc.). Take note of the orientation of the LCD glass! It makes contact with the PCB by means of a couple of flexible contact strips at the top and bottom edge, but once you remove it, you may not be able to determine the correct orientation. Maybe some masking tape on one end would help. The polarizing film needs to be removed. It adheres pretty tightly to the LCD glass. You'll need to get a sharp blade under one corner to start it. Once it's started, pull it off by applying a very steady pressure in a plane parallel to the LCD glass--if you pull perpendicular to the LCD glass, you'll quite possibly break the LCD. While you're pulling, try hard not to disturb the contact strips at the top and bottom edges--you don't want these to come off. Then take your polarizing film (the new stuff you're using for a replacement) and place it up against the LCD glass. Rotate it until you see the minimum light reflected from the LCD glass (i.e. it gets darkest). That's the correct orientation for the polarizer if you want your LCD inverted. Then cut your piece to size, cut it to fit inside the metal bezel since you can't adhere it to the LCD. Replace the LCD glass on the board, making sure the orientation is correct and that there's no crud between the board and contact strip. Replace the cover and twist the tabs back into place. Et voilà. {param} There's another guide here. For polarising film suppliers see the next question. As for changing the LCD colour, it depends. There are quite a few ways of backlighting an LCD, some can be changed to different colours easily... -Side LED lit (1 or 2 leds), the easiest to change, just drill out the old LED and pop a new one in -EL Sheet lit. I've never worked with EL sheet but I hear it's not the easiest thing to setup. Theoretically if your display has an EL sheet under it for backlighting, ripping it out and putting some new sheet under should work. Farnell and all good electronics shops sell EL sheet (as do modding shops). -LED Array. I doubt anyone could successfully remove the large number of surface mounted green LED's in an LED array and replace them (well you could, in fact Brent from Crystalfontz has, bur I wouldn't try it!). If you could you'd need to be rich to be able to afford it. You could pull the whole array off and replace it with some EL sheet though. -CCFL (cold cathode florescent lamp) - I've never played with a CCFL lit display, I think a filter in front of the tube should change the colour nicely though. This said there are other things to consider... green displays frequently have slightly yellow glass. The way an LCD works, by polarising the transmitted light, only works at certain frequencies... even if you meet and beat all the requirements above you could find on power up that the lovely contrast of your old green display has now washed out into a haze of your new blue. In general green displays have the best contrast and red displays are the worst. If you don't fancy doing the hard work companies like Matrix Orbital and Crystalfontz sell a wide range of different coloured (and inverted) displays. Where can I get polarising and coloured films? US online source: http://www.scientificsonline.com/EC/Products/Display.cfm?categoryid=192873 The experimental grade is just fine, and much cheaper. Camera shops are the most likely places to find the stuff. Uk sources: Zytronic Displays Ltd Patterson Street Blaydon on Tyne Tyne and Wear N21 5SG tel: 0191-414-5511 fax: 0191-414-0545 web: www.zytronic.co.uk contact: Morag MacDonald Optical Filters Ltd 14 Bertie Road Thame Oxon OX9 3XA tel: 01844 260377 fax: 01844 260355 web: www.opticalfilters.co.uk Contacts: Peter Fisher, Samira Adlane Clarex / Weatherall Equipment & Inst. Ltd Unit 1, Station Approach Wendover Bucks HP22 6BN Tel 01296 622180 Fax 01296 624955 Contact Roger Worthington email: rhcworthington@msn.com Web: www.weatherall-uk.com Instrument Plastics Ltd 35 Kings Grove Ind Estate Maidenhead Berks SL6 4DP Tel 01628 635961 Fax 01268 773299 Contact Mike Wevill Lee Filters Central Way Walworth Ind Estate Andover Hants SP10 5AN tel: 01264 366245 fax: 01264 355058 Web: www.leefilters.com Contact: John Young PSC A/S Industrial 13-17 DK-9700 Bronderslev Denmark tel: 0045 98 82 29 99 fax: 0045 98 80 00 85 web: www.psc.dk Contact: Kristian Jacobsen Tech Sales Manager Farnell and Maplin will both sell you coloured filters online. Where could I mount one of these displays? There's only one display I've seen that will fit in a floppy bay, the 2x20 parallel display 3167690 (and 2x16 brother 3167689) from Farnell. Most 2x20 displays will fit comfortably in a standard 5.25" bay, while anything bigger (4x20 is the next most common size) normally needs two bays if you're planning on internal mounting. Matrix Orbital's white graphic GLK12232-25-sm can display 4x20 characters, and Noritake's 4x21 equivalent graphic VFD's (in normal dot size) can both fit in a single bay - these are 2 exceptions to the rule. For external mounting inspiration have a look at this. {param} What are the pros and cons of an EL backlight over an LED backlight? Displays using an EL backlight have a bluish green look to them. This is more consistent over all of the display, and the display is thinner than a regular LED backlit one. Pros of EL: Thinner display Lower power consumption Cons of EL: Low life span. (10K hours EL vs. 100K hours LED)* Not as bright as LED *Time until the brightness decreases to the half of the initial value (thanks to Henry from MO for this one!)
LCD Software, what should I use? For the four main classes of display which need software to drive them (Serial alphanumeric, parallel alphanumeric, serial graphic and parallel graphic), I'll list all the available software I know of and give a short summary of it together with a star rating out of 5 (to reflect my opinion of it!). Serial alphanumeric LCD Smartie Cost:: None. Rating:: **** Stability:: Good. Support:: ? Author working on the next version?:: Yep Supported controllers:: Matrix Orbital, Crystal Fontz (and parallel's). Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Improved greatly over the last few years, now has many features and is simple to use - highly recommended. Where to download:: http://lcdsmartie.sourceforge.net/ LCDC Cost:: ~$20 Rating:: *** Stability:: Few known issues. Support:: Lots, has its own forum here. Author working on the next version?:: Yes Supported controllers:: Only Matrix Oribital officially, unofficial files for the BG Micro VFD, the Seetron controller and some Noritake displays. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: No other piece of LCD software has been as well developed or offers as many features. It's good, but it's expensive. Where to download::http://lcdc.planetdps.com/downloads.htm Crystal Control Cost:: None. Rating:: *** Stability:: Quite a few issues, worth trying before you buy an LCD that relies on it. Support:: Some, though author not always helpful, ask your questions here. Author working on the next version?:: Yes Supported controllers:: Crystalfontz only. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: CF's flagship software, should get better when more features are added. Where to download::http://www.crystalfontz.com/software/crystalcontrol/index.html LCDstats Cost:: None. Rating:: ** Stability:: No known bugs (??). Support:: Some, ask questions here. Author working on the next version?:: Unsure (no updates in a long time, though next version has been promised). Supported controllers:: Matrix Orbital mainly, Crystalfontz version is available. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Solid, reliable program with some nice features for MO displays (good keypad and GPO control), not very customisable though Where to download::??? LCDD Cost:: $19.95 per single license Rating:: ** Stability:: No known bugs (??). Support:: Good, see here. Author working on the next version?:: Yes. Supported controllers:: Crystalfontz (model 634 only). Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Good reliable server monitoring software. Where to download::http://www.2morrow.com/lcdd/ LCDMax Cost:: 15 euros for the normal version. Rating:: ** Stability:: Few known bugs. Support:: ?? None that's easy to find. Author working on the next version?:: Unsure. Supported controllers:: Crystalfontz with Matrix Orbital support. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Fairly feature rich with a plugin scheme similar to LCDC's. Where to download:: ?? LCDProc Cost:: None. Rating:: untested Stability:: ? Support:: FAQ on website. Author working on the next version?:: Yes. Supported controllers:: Lots. Supported OS's:: Linux. Comments:: The best Linux LCD software I hear Where to download::http://lcdproc.omnipotent.net/download.php3 LCDriver Cost:: None. Rating:: * Stability:: No known bugs. Support:: FAQ on the website. Author working on the next version?:: Yes. Supported controllers:: Most. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Old hat, version 2 promises a lot but has yet to deliver. I'ts biggest boon is wide ranging support. Where to download::http://lcdriver.pointofnoreturn.org/ LCD Studio Cost:: None. Rating:: ** Stability:: Bit buggie. Support:: None? Author working on the next version?:: Yes. Supported controllers:: Matrix Orbital, BG Micro VFD, others? Supported OS's:: Windows NT/2k/XP Comments:: Nice software, big buggie. Where to download::http://www.lcdstudio.com/ Winamp2 plugin Cost:: None. Rating:: *** Stability:: No known bugs. Support:: None. Author working on the next version?:: Yes. Supported controllers:: Most. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Very good for those only wanting winamp info. Where to download::http://www.markuszehnder.ch/projects/lcdplugin/download.html Serial graphic LCDC Cost:: $17.50 Rating:: *** Stability:: Few known issues. Support:: Lots, has its own forum here. Author working on the next version?:: Yes Supported controllers:: Only Matrix Oribital officially, unofficial support for noritake displays exists (on our forum!). Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: This software was designed for character displays but can be hacked up to work with graphics! Where to download::http://lcdc.planetdps.com/downloads.htm MODG Cost:: None. Rating:: * Stability:: Few known issues. Support:: Some, ask questions here. Author working on the next version?:: No. Supported controllers:: Matrix Orbital graphic displays. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: MO graphic test software. Where to download::http://www.matrixorbital.com/download/mogd .zip Winamp LCD Plugin Cost:: None. Rating:: *** Stability:: ?. Support:: Some, ask questions here. Author working on the next version?:: Yes. Supported controllers:: Matrix Orbital LCD GLK12232. Supported OS's:: Windows 9x/ME/NT/2k/XP Comments:: Looks nice. Where to download::http://www.xs4all.nl/~hansolo1/lcd.htm Parallel alphanumeric The following applications all support parallel alphanumeric displays; LCDSmartie, Crystal Control, LCD Studio, Winamp Plugin and LCD Proc. See the links in the serial section for downloads. See also http://www.jalcds.de/ (// only software). Parallel graphics I've not had chance to play with any parallel graphic displays yet, so I'll just post the links http://www.skippari.net/lcd/ http://gfxlcd.schijf.org/ http://www.xs4all.nl/~mandark8/got/PowerLCD v0.3.zip http://www.markuszehnder.ch/projects/lcdplugin/download.html http://www.powerlcd.nl/ http://liquid-mp3.schijf.org/ http://www.lcdstudio.com/
I've just finished wiring myself an alphanumeric parallel LCD and it doesn't work, help (!) (Far too many people ) I'm going to deal with a few common scenarios but first if your new parallel LCD is non-functional you should check that; - The display you chose to buy has a HD44780 or compatible controller (assuming alphanumeric). - The pin outs in the datasheet for your display match the expected pin outs in the wiring guide you are following (it is easy to assume because the controller on your display is the same as the one in the guide you chose to follow that the interface (normally 16 pins) is laid out in the same way. This isn't always the case, though normally is. If you pin layout is different then use the descriptions of the pins functions to work out how to wire your LCD from your guide of choice). Multiple interface displays (like the cheap $20 VFD from BG Micro) often use unconventional pin layouts. - You didn't make any wiring errors... it's easy to put the wrong wire in the wrong place. These all passed the only remaining errors can be; human (badly soldered joints, unwanted shorts), hardware (damaged display, wires, motherboard etc.), software (improperly installed). Saying this doesn't really help though so here are some common scenarios and the source of the problem, 1. On power up the display doesn't do anything. At all. Ever. I haven't seen a HD44780 or compatible parallel wired LCD yet that doesn't show a test screen on first power (normally odd lines are solid, e.g. black bar on the first and third lines of a 4x20 display). If you don't see this make sure your LCD is getting power to the correct Vin pin (normally pin 2), that the LCD is correctly earthed (normally pin 1) and that the contrast of the display isn't all that's stopping you seeing the test signal (normally earth pin 3 for max contrast). VFD's (and PLED's) on the other hand, I've yet to see one that does display a test screen on power on - so if you've just wired a VFD up and it does nothing when power is supplied I wouldn't be surprised it probably won't until you send data to the display. If your display has a backlight and by nothing you mean 'and even the backlight doesn't come on) then you've probably messed up big time. The backlight's +ve power normally goes to pin 15 (or 'A'), make sure you're delivering the correct voltage to this pin, and also that the backlight's -ve is properly earthed (normally pin 16 or 'K'). A possible source of problem is if your LCD came with an EL sheet backlight and no invertor - refer to your LCD's manual to see if this is the case, if so you'll need to source the correct invertor and wire it in. 2. On power up the display fills up with random gibberish. This is a good one... probably a broken controller (either parallel or LCD) but check your wiring. 3. On power up the display starts smoking, catches fire and starts burning your desk. (or your computer dies) This generally happens only when you get things very very wrong. I've seen two people kill their motherboards and only one person set their LCD on fire. It can happen though so make sure you follow your chosen guide properly. If this does happen to you it is possible that it was an LCD fault that caused the mass destruction. I doubt it was though. 4. On power-up I get a test signal but I can't make the display do anything else. The test signal is a good thing - the display is probably healthy, though you parallel port might not be, though your port is probably not the problem. After double checking your LCD software's config., reading the manual for it six times and trying other software if you still can't make the display work it is probably a wiring error. Seeing as the display isn't responding to anything coming down the data lines you can ignore these (at first anyway) and concentrate on the pins which set up your display and tell it when to respond to the data lines, normally pins 4 (//16), 5 (normally earthed) and 6 (//1 - enable strobe). Resolder these and make sure you have no shorts anywhere. If you really can't find any problems try the display on another computer, your parallel port may be b0rked or the displays controller may have died. 5. On power-up I get a test signal but when I try to use LCD software I get gibberish on the screen. If your display is showing the correct number of letters (i.e. you send 'test' and it displays '^"$£' and not 'djjso209') then the problem lies in the wiring of the data lines (one improperly connected, two shorted, two soldered the wrong way round etc...), you can normally work out which data line is at fault by looking at the ascii character values of the printed text (i.e. you send 'aaaa', ascii character 97 and get 'AAAA' ascii character 65 then you know that the 6th data line is improperly connected as it carries a value of 32 (2^(n-1)). Don't worry if you didn't understand this, basically just check your data line soldering If you get the wrong number of characters back then the problem is more serious, though probably still down to bad wiring. Also don't forget to make sure that you haven't accidentally shorted any of the other components on the back of the LCD. If you really can't find any problems try the display on another computer, your parallel port may be b0rked or the displays controller may have died.
These FAQs are reposted from [H], but I am the original author --linear Q: How can I stick a laptop LCD in my desktop case? A:You need (at minimum) a controller. Laptop LCDs do not interface directly to VGA. You may also need an inverter for the backlight. Q: Where can I get a controller for a laptop LCD? A: EarthLCD has them. Expect to pay a couple hundred US dollars for it. You can also buy complete kits there. Q: Can this actually be done? It sounds very difficult! A: Yes. It's been done, by tiberius on [H] foums. (no link currently available) Q: what are my other LCD options? I don't want to plonk down that kind of cash. A: Somewhat less expensive is to use an with NTSC video input (like these mobile video units), and drive it with a vid card that has a TV out. This is the approach used by widefault with his LCD mods. You can read more at his site as well as in various threads on [H] forum. Q: I'd like to get something working on a color LCD for under a hundred bucks. What are my options? EIO deals in overstock LCDs and occasionally has usable color units for around $100, but you need to check their site fairly often. Timeline also has cheap LCD displays on a sporadic basis, however many do not have a controller, and won't be easy to interface with your PC. Serious hackers only. Q: What are my color LCD options above a hundred bucks? A: PartsExpress EarthLCD has NTSC displays EarthLCD has VGA (and better) kits with a PCI or ISA controller. Various other electronics houses carry LCD displays for mobile video applications. Q: Will one of these NTSC displays look as good as a VGA LCD monitor? A: No. But it can certainly look good. Q: What do you mean by NTSC video? A: NTSC stands for National Television System Committee. For purposes of driving a display, NTSC (or composite) video is the signal fed from a video source using an RCA connector. Outside of North America, other video formats are standard. PAL is the standard for Europe. Most vidcards should allow you to select NTSC or PAL format on the TV output. Q: I'd like to hack the LCD from a GameBoy into my case somehow, can I do it? A: According to Jeff Frohwein's GameBoy FAQ it is possible but complicated. The LCD interface to GameBoy is very similar to other large screen LCDs in that a CRT controller is really required. The reason for this is that all 23,040 pixels (160x144) have to be written or "refreshed" 60 times a second the same way that a TV has to constantly redraw or else there won't be any picture. This is required even if what your trying to display is static and never changes. This is all the info I have at the moment. (note that the above FAQ does not appear to be actively maintained.)
Q: What are GPOs? A: GPO Stands for general purpose output. There are GPOs on most Matrix Orbital LCDs and VFDs. Using software, you can toggle these on or off. Then devices attached to the GPOs are triggerable from software. The standard GPOs on most displays can source 20mA @ 5V, which is great to light up an LED directly. The LK204-25-PC has high power GPOs that can handle more current, and can be used to driva a fan directly. The ordinary GPOs can be used to switch a fan or other load on/off with the addition of a transistor (watch for a BiT-Tech guide on this soon). Q: What does keypad support give me? There is a connector on several Matrix Orbital displays that allows attaching a keypad. The software that drives your LCD will need to interpret the keypresses and act on them in order for anything to happen, but a typical use for them is to control Winamp or another program. LCDC offers a comprehensive set of features to work with both keypads and GPOs. You can flexibly map keypad presses to Windows events, and use GPOs to indicate various conditions that you may be monitoring with LCDC, such as mail in the inbox, or a temperature alarm from MBM. For more details refer to http://www.bit-tech.net/article/77/.
Q: My computer has neither a parallel port nor a serial port, what should I do?(Randland) CrazyJester: A: You can get a usb port replicator to get parallel, serial, and more, or, they have usb-parallel and usb-serial adaptors. You can also buy paralell and serial pci adaptor cards... The USB adapter will put you back about US$50, port replicators US$60-80, and cards would be around US$20-40... (US$/1.5 ~ £) Cheese: A: You local electronics shop should be able to sell you a USB convertor, see www.maplin.co.uk (product code ZP43W) in the UK or www.crystalfontz.com in the states. Beta124: Link to $20 converter http://www.byterunner.com/cgi-bin/c...act_match=exact
Where to buy. Serial LCD's and controllers Matrix Orbital displays - http://www.matrixorbital.com/ - they will sell worldwide but see the list of distributors for a local retailer (http://www.kustompcs.co.uk/ or http://www.coolercases.co.uk/ in the uk). Crystalfontz displays - http://www.crystalfontz.com/ - they sell worldwide. Seetron displays - http://www.seetron.com/ (US), http://www.milinst.com/ (UK), http://www.maplin.co.uk (UK), http://www.farnell.com (UK, Europe + some other places). Other serial LCD's - http://www.farnell.com (UK, Europe + some other places), most electronics shops. Controllers - http://www.milinst.com/ (UK), http://www.seetron.com/, http://www.wirz.com/, http://www.hvwtech.com/, http://www.usblcd.de/ (USB daughter board). http://www.jacodisplays.com/index.asp Parallel LCD's Crystalfontz displays - http://www.crystalfontz.com/ - they sell worldwide. Most good electronics shops (e.g. http://www.farnell.com http://www.maplin.co.uk) Good US store Eio - super cheap parallel LCD's They will ship outside the US. See also http://www.modwarehouse.com/ (acrimonious) VFD's Noritake - http://www.noritake-itron.com/SubPages/vfsalesoff.htm Pick a sales office of your choosing, email them and they'll sort you out Noritake-Itron in the UK will sell you one, or www.farnell.com stock their parallel character VFD's and some others. Matrix Oribtal displays - http://www.matrixorbital.com/ - they will sell worldwide but see the list of distributors for a local retailer. Digikey - www.digikey.com (US noritake supplier). BG Micro - http://bgm.bgmicro.com/ once sold cheap character display, old url no longer works though
Q: Where can I buy touchscreens and other miscellaneous LCD-related paraphernalia? http://www.earthlcd.com/ has more junk that you can shake a stick at, including touchscreens, backlight inverters, controller cards, kits, etc. etc.
Q. I'd like an LCD to fit in a single 3.5" drive bay please, can you help Cheese? A. Yep Farnell code 3167689 for a 2x16 bare parallel LCD module which will fit very comfortably in a single 3.5" bay. {param} {param} It comes with a green backlight, but it's easy to change to any colour you want: {param} Wiring as: 3 - earth 4 - +5V 5 - earth 6 - // pin 16 7 - earth 8/16 - // pin 1/9 17 - +5V 18 - earth Q. Can I use my Palm PDA as a display for my PC? (jcy0001) Why yes, a little program called Pebbles is what you want. Also have a play with PalmVNC. (beta124)
Q: I have an old portable LCD TV and I want to use it as a display for my PC. My question is, How? A: Check out http://www.rickard.gunee.com/projects/video/sx/howto.php Now, just figure out a way to connect the microcontroller to the RS-232 port and write some code for the microcontroller so it can be controlled with software for graphical LCDs! Q: Now that I have the interface issue fixed, how do I power the LCD TV from my PC's PSU? A: If it takes 12v, just wire it to the 12v line in your PSU. If it takes 9v, use a 7809 regulator powered off the 12v(be sure to heatsink the regulator!). If it takes 6v, you can either try connecting it to the 5v line(4 half-used AA batteries often drop to around 5v or even less), or use a 7806 regulator powered off the 12v of your PSU(again, be sure to heatsink the regulator!). If it takes 4.5v, you can try connecting it to 5v(but you will risk letting the smoke out), or drop the 5v to ~4.4v with a diode.
Q: I've wired up a parellel LCD and it work but it seems to be getting very hot, bad sign? Shogun A: Depends on the LCD, some do run hot, but it's normally a sign you're putting too much voltage across the backlight... did you just connect pins 15 and 16 to 5V and earth? Check the spec sheet and make sure it's right. Q: How can I convert my hd44780 LCD to be driven from the serial port? Sardien A: I've listed some retailers of strap on boards for parallel - usb and parallel - serial conversion above. Building a circuit yourself unfortunately requires so much logic that the only real way of doing it is to program a PIC (which requires a fair amount of dedication to the cause). Q: Any idea where i can get some info on programing for a parallel display in visual basic? Acrimnoninouis A: I've never tried to control a // lcd with VB but I'd say have a good read of the documentation for port95nt http://home.t-online.de/home/340020127737-0001/port95nt.exe it's the standard // driver that nearly all // lcd software abuses. Q: What is the max length for a parallel cable used to connect a hd44780 LCD? Sardien A: d question! Noritake Itron normally say just 10cm for thier parallel VFD's IIRC. In reality the limit is much longer than this, I've used 2m cables on a variety of displays without issue... exact length varies depending on the controller - anything up to 2m should be fine, but if you're having troubles there are a few tricks you can play (putting a small resistor on the E line often helps for some noritake // VFD's for example). Q: What would be a good cheap case to house a 4x40 LCD? Gish A (Acrimoninious): There has been alot of discussion about LCD mounting in this thread recently: http://forums.bit-tech.net/showthread.php?s=&threadid=37280 And if your after some ideas/inspiration here's a great place to stop by: http://iceforums.net/lcd/ Q: My parellel display only has 14 pins,how do I wire it up? Shogun A: Pins 15 and 16 usual power the displays backlight, if your display only has 14 pins it normally means that either your display doesn't have a backlight, or that the backlight draws its power from elsewhere (maybe two pads labelled 'A' and 'K' for example).
Download link for LCD Smartie: http://backupteam.gamepoint.net/smartie/ I rather like this one, since it has "conditional" screens, and does support parallel HD44780, MO, and CF displays. It also shares a wiring pattern with LCDStudio, for the parallel displays.
I have read something somewhere about connecting up a gameboy screen - IIRC it needs a VGA input cycled at an odd frequency which makes it pretty damn difficult to use I'm afraid Rob.
That's not an LCD. That's an LCD controller. I don't think there really is an LCD that stands above the rest.
Very true, what i ment was an interface, by having to comply to the standard, it has to have the LCD Bias internally generated (normally this is -ve supply). It has 8 custom charactors, has to be dioded to prevent discharge (safe to handle) and is very very cheap (you can pick up surpless ones for £5 !) If its actual LCD i think it would have to be a nokia LCD they made for a range of their phones, i think it was the 3350 or some such cheap model, ironically these don't use the controller i have just pimped above, but the LM6415 was rampent in the MP3 players everyone (myself included!) all rused to build, then never actually made into a case because of the hudge PCB size, and just went a bought a NetMD. Post dedicated to the MPEG2 Encoder/Decoder Chip with built in DAC sitting back in its static wrap.
Hi! Has anyone successfully interfaced the LPH7366-controller with a PC? This controller is used on the displays found in Nokia 3310 phones which has 84x48 pixels and are cheap as.. eh.. i dunno, they're cheap anyways I think they use some form of serial data, but I'm not really sure. I've googles around a bit bit only found interfaces with misc micro controllers, nothing about RS-232 or so.. Thanks in advance!
Wow, I just found some new software for all kinds of LCDs - http://www.lcdhype.de.vu/ It's really neat, so far - it's got a built-in scripting language, for starters, so I can TOTALLY see doing some thing things. It seems to handle graphic and character displays JUST fine. I'll be playing with THIS one for sure. =)
www.allelectronics.com has some decent parallel lcd's. there's a 16x4 that should fit into a 2-unit 3 1/2" disk opening. also, tried out LCDcenter3.0 recently, would NOT recommend this, has issues with recent MBM versions, and low level of adaptability compared to crystalcontrol 1.06, which works very well on my setup. my $0.02
