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HD44780 lcd

nikko

New member
Hellol!

I have a lcd that is very similar to the CRYSTALFONTZ parallel display that i can`t get to work, when power on all segments goes black and then fades, after that nothing happens when i use the crystalcontrol software. That all segments go black and then fades, does that indicate that the lcd is working ???
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CF Support

Administrator
Check your wiring, that's almost always where the problem lies.

Good wiring guides for HD44780 compatible LCD's can be found:

http://www.myrolypoly.com/lcd_project/lcd_project.html

http://www.icehw.net/article.asp?id=104

http://www.geocities.com/ResearchTriangle/1495/ee_lcd.html

http://www.overclockers.com.au/techstuff/a_diy_lcd/

http://www.hardforum.com/showthread.php?threadid=248302

You can also go to http://forums.bit-tech.net/showthread.php?threadid=5582 and search for "assuming alphanumeric" and you will find a short Q/A post on parallel displays.
 

nikko

New member
Hello, i have checked the wiring, i am actually starting to suspect that the paralell port doesen´t output the signal from the program because the display reacts when i power up the computer but it doesen´t respond to programs i try, it´s from a fax so it doesen´t have the controls for contrast so i can´t check if it´s that, it had a 74HC164 shift regiter chip when i found it but i had to remove it because serial doesen´t have the E and RS signals so it had to go. That it respond when i turn the computer on, is that a sign that the lcd is working ?
 

spock

New member
Bad...

Well, first of all, I'd like to say that the fading thing is bad. Sorry, but that fading only happened on two LCDs I had fried. No wiring can produce fading, only the burning of the LCD itself.
I myself started the cruise into the LCD world with a 16x2 character LCD taken from an old fax machine! Just make sure you know what ICs are used in the LCD, and that they are compatible to the HD44780 standard. Then, make sure you know the pin-out of the module, and connect the right pins to the right places. All the LCDs I've seen operate on 5Volt Vcc and all the character LCDs I've seen have GND on pin #1, Vcc on pin #2 and most of them Vlcd on pin 3. HOWEVER, nothing excludes a proprietary pin-out. Make absolutely sure, and in case of doubt, use a multimeter.
The 74HC164 is not just a shift register, it's a parallel out shift register. So, it was probably used to parallelize a serial data stream into the LCD. No worries on that.
If you can get a picture or two, it might help!
 

nikko

New member
I don´t have a camera, after i removed the 74HC164 chip i used a digital multimeter to find the right solder pads for the data bits, first time i powered it up i had the polarity wrong :'( there are 4 leds on the board too and they had one pin connected to v+ so i thought that was ground, it also looked like it well well, i guess i have to buy a lcd now :(
 

slipperyskip

New member
Can anyone explain to me why people are using parallel LCDs when this forum is filled with horror stories about them. Crystalfontz has clearly stated that they won't warranty them or support them in a PC application. What am I missing here?
 

nikko

New member
maybe some ppl don´t like the plug in and play units, some ppl may want to do the stuff themselves
 

spock

New member
True

When I say "the LCD itself" I mean the circuitry of the LCD that exists on-glass. Can you explain a little more on that "Anyone out there that can sponsor with a used and known working module ???" perhaps?
Now, about the parallel thing, it's true, some people like to do things themselves. I've been using parallel LCDs for quite some time now, and no "horror stories" ever happenned to me, not one that wasn't my fault, anyway. Other than that, and the people over at CF excuse me for that, but CF people are just covering up their back by not supporting parallel LCDs for PC use. Meaning that, indeed, parallel LCDs are more difficult to handle and connect, so more problems are prone to occur. So, in my humble opinion, they are just saving themselves the trouble of troubleshooting all those that made the wrong connection, and escaping the inevitable harm to their reputation that would happen when some users burn their LCDs from wrong wiring and don't get a replacement. And finally, CF people are not gods. The fact that they don't support parallel LCDs does not make the use of them prohibited by divine law.
After all, there are hackers, there are modders and there are posers. You all posers can use the USB and serial LCDs and appear *cooooool*. :p
 

nikko

New member
I liked your lil display, makes me want one even more. This lcd thing started as a small computer based mp3 player when i found a 16x1 dot matrix lcd in a ledpage printer made by oki, i tried to make it work and ended up with a smoking hd44780 :( then some days ago i remembered the other lcd in the parts from a thunder destroyed fax i had laying around so getting that, checking on the internet for schematics, tracing every trace for the signal and when that was done time to try to give it some v+, and of cource prong polarity because of some stupid leds that fooled me :( but anyway make a cable for testing it anyway, 2 days of testing without any good result. display is now considered DEAD!!! :( :( :(
 

slipperyskip

New member
Re: True

spock said:
After all, there are hackers, there are modders and there are posers. You all posers can use the USB and serial LCDs and appear *cooooool*. :p
I'm sorry but I've had this on my to-do list for too long.

Spock: I'd flame you but I'm too busy posing for magazine articles and web-based pictorials about my work. Oh, and I forgot all about those modding books that are coming out soon. I have several different poses in those. One of my computers is at TechTV studios right now, doing what? You got it. Posing.

Good, I'm glad to get that off my list.
 

spock

New member
peace

Okay, since you got that off your list, I can have a say, I guess!
Although I still stand to what I said back then, there are two things I should make clear:
First is, posers using serial and/or USB LCDs doesn't reverse to mean that all people using serial and/or USB LCDs are posers.
Second, there's really nothing wrong with posing! After all, there are people that have the knowledge, the time, the money and even the "good hands" to do stuff, and there are people who just like a *cool* case. After paying for it, why not show it off?

If you still feel like it, you can always get back and flame me! I really won't hold a grudge!

Finally, I've noticed and admired you and your work for some time now, always from this site's posts. Apart from any subjective opinion about the general aesthetics of your creations, which I will hold for myself, it's more than clear: you've got the "touch"! ;)

Cheers!
 
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