Q. Where can I learn to control HD44780 based LCD's? A. http://www.myke.com/lcd.htm http://www.geocities.com/dinceraydin/lcd/intro.htm
Got a crystalfontz CFAG12864B-TMI-V all wired up here and using a test program. I get this... its sort of striped, text sometimes gets letters wrong and some display codes appear on the display, images look better but still suffer from striping. I've checked for shorts and general wiring but can't see any problems. Can anyone point me in the right direction for trouble shooting? Thanks in advance, EDIT: Tested some more, with liquid mp3, just displays a garbled image. Also it does not get letters mixed up if i send them, one at a time.
Hard to even know where to begin with troubleshooting, so lets see if we can't get some comments together to make a little guide. First check nothing else is trying to use the LPT port (assuming thats what your using). There is no easy way to see if anything else is using the ports, so download portmon www.sysinternals.com and have a look. If nothing else is using the port. Check your code, make sure your addressing the right screen layer (ie text rather than gfx). Failing that check your pin wiring, remeber some of the parport status pins are inverted. Check http://www.doc.ic.ac.uk/~ih/doc/par/ for pinout info.
In some cases, you can use an old 1MB PCI video card for a controller! http://forums.bit-tech.net/showthread.php?t=51818 ]
I have a non standard HD44780 controlled 2 x 40 lcd so I have been searching for some time to get the pinouts of the chip itself so I can trace back to the plug. Most guides I have seen only give pin no and function for input connector. Anyway I found this Hitatchi HD44780 Datasheet. and thought it maybe helpful to others too.
I have two lcds that give me the exact same problem. I'm not sure what it is, though in all likelyhoo it's something stupidly obvious. I noticed in some other diagrams that pins 18-25 on the db 25 connector were earthed. does this affect the displays at all or is it just good housekeeping for the port? I'm fairly irritated at these lcds with their accursed test lines- hopefully this vfd I've got will be more co-operative.
DSTN display I have read the FAQ and still havent found anything about conecting a 640-480 black and white dstn display to a serial or parallel conector is this posible does any software support it If i run this on a pci vid card will that be posible to do that and so on i have two lcds both are running a 15 pins I talked to my dad who used to work for telecom and had something to do with the pay phones and he told me they have a wonderful 4X24 or something screen and are all ready to go so i will inquire about this tomorrow and get back to on those
Possible? Yes. Practical? No. Unless you are an electrical engineer or have a large amount of experience in that field - it will simply require too much time to do.
Apologies if this has been answered, just read the whole thread and couldnt find an answer amongst all the people asking about laptop displays Q: Ive seen cheap LCDs for sale with EL backlights but they say they need an inverter. What does this do, is it necessary, where can I get one and are they cheap? thanks 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) The answer was, surprisingly, in the FAQ.
does anyone know how to wire CPX - Shift Clock FRM - Frame Start Load - Latch Pulse to a printer port ?? its coming from a 640x400 OKI M5298/B contoller
The inverter converts 12V or 5V DC to around 80-100V AC to run the EL. Finding one that matches the spec voltage and frequency can be very hard, and the ones I've seen have been £25-£30 expensive. The inverters are designed to run a certain panel area too, which limits choice.
There is a thread where Smilodon is trying to use a USB to Parallel cable, to connect his parallel LCD to a USB port: USB->paralell He has not been able to make it work, yet. I agree with Smilodon that it would be interesting to have it done. I have read in other forums that it is not possible, as Windows XP handles the new port only as a printer port, and only the printer driver can recognize that port. Any one can help? Any one has succeded connecting a LCD using this kind of USB to Parallel cable? Thanks in advance.
That's gonna be hard, you'll have to gather all LCD authors and convince them to write one universal USB driver. There are some LCD apps that support their own propietary USB interface already. edit: OK found it again here.
one small addendum... I know I've wired everything up correctly, but even when I turn my contrast dial through its entire range, I only get the faintest ghostly characters. You may have an LCD panel that is designed to operate under extreme temperature conditions. I purchased one of these from a surplus supplier, and was very excited to get it to work. But alas, I couldn't get the screen to display characters with any strength. If I tilted my head at the right angle, I could see vague ghosts, but nothing substantial. It turned out that, because of its special resistance to heat or cold, this panel had different voltage requirements: Vo (VLc in some instructions) needed a slight negative voltage, about -0.5V. Vo is tied to the 'tap' (that's the part that's connected to the dial) on the 10K potentiometer (see this diagram). One of the extremes of the potentiometer should be tied to a +5V source, and the other to ground. Now here's where I had to do things differently. Instead of tying the other end to ground, I tied it to a -5V line that went to my motherboard. Now the tap of the potentiometer is straddling between +5V and -5V, which is a 10V range. This was okay, because my panel's datasheet said it could handle 13V difference between Vdd (aka Vcc) and Vo. After making these modifications, I carefully turned the dial from its centre-point (0V, because it's exactly halfway between +5V and -5V) towards the -5V side, and voila! Lovely dark characters leapt into view. Feel free to e-mail me at paul (at) heliosville (dot) com if you have any questions.
I remade the circut, using the LCD Smartie circut drawing, and still, it doesnt move from that damn output!
For laptop LCDs, it might be possible to build your own controller with a FPGA! http://www.fpga4fun.com/GraphicLCDpanel1.html You can attach ADCs or LVDS receivers to connect to VGA or DVI.
Some more info about graphical displays: If you are looking to buy a mono graphical display, please take note if it has a built-in controller like the SED133X or T6963. Without these controllers, your buying what is esentially a neat paper-wieght or 3 months of your free time (if you have the apptitude to build your own controller). The easiest way to determine an LCD if it has a controller built-in or not is to google the datasheet. If the pinouts have D0-D7 and WR/RD/CS, then it most likely has a controller. If the pinouts have something like XD0-XD4, FRM, CP, FP, or Clock Shift, its controllerless. If you have a controllerless LCD already, its not a lost cause: You can purchase a controller card for $40USD. Google SED1330/SED1335 and eventually you will find some places that sell just the controller card. This will only work for LCDs that are at most 640x256. Anything larger is not supported by these controllers. To go beyond 640x256 (mono) there is also the S1D13704 or the S1D13504 chips. They can also handle color TFTs. But be warned, these are 100TQFP packaged surface-mount chips. Ontop of that, they use an addressing interface, so theres no chance in hell to hook up to parallel/serial port. This interface is meant for embedded microprocessors. Needless to say, theres no software support what-so-ever. Important note: Most graphical LCDs require a negative voltage to drive the LCD. There is no way (ignore what others suggest) to drive them directly from a standard PSU. There are 3 options to get this negative voltage. Allelectronics sells a 5V-to--15/-19/-26V DC converter for $0.50USD part number DC-32. It requires capacitors on all inputs and outputs, and can only source a few milliamps. It does the job for most LCDs, but not all. Second option is buy a wallwart or cheap small PSU ($2 ones found at allelectronics or goldmine) and wire them up with postive going toward ground, negative feeding the potentiometer your using for your LCD. Third option is to connect 2 9V batteries in series (same way as wallwart mentioned above). The 9V battery trick is very usefull and easyto make sure your LCD is working correctly before wiring up a PSU, but is not a very good long-term solution. VFDs: I currently have a good collection of odd VFDs, including a 320x240, a 256x64 thats 14 inches long, and a few character ones that have funky parallel interfaces. I play with PICs in my spare time, so its all good for me. But for most users, theres no software support. When looking for VFDs, make double sure that you find software to support it. One good place to look is VFDthinger. Or, try to find character VFDs that are drop-in replacements for HD44780 LCDs (they have the same pinout interface). Hope that helps to clarify some stuff commonly asked.
Very good summary Hazer. I'd like to mention something about the SED133x controller though. Not known to most people is that this controller isn't perfect. Displays using this controller exhibit some kind of distortion and pixel artefacts. Better explanation here.
I think the only (and factible) way is to buy another paralell port card. Also, there has been some discussion about using a usb to paralell cable, but it looks that those cables are only valid for printers. Anyway, I wanted to say that I am really interested in your thread. I want to install several lcd's and at least two of them need a paralell port. Another solution would be to use one of those electronic devices that connects to the lcd pins and offers usb connection, but they usually are quite expensive, and only works with character lcd's.
