Hi everyone. Here's a weird one for you...

[Gman83]

Hi. I am so sorry to be posting in your forum but desperate times call for desperate measures, as they say...

So for the last 4 months I have been building a midi electric drum controller from this website http://www.megadrum.info . The project's creator has been helpful, but he is really busy and he has tried helping me with this issue but so far no dice.

I have salvaged a working UTC 2x20 LCD for my project from a discarded network peripheral and contacted UTC for the correct datasheet for the LCD ( https://app.box.com/s/dhoevozw1yqhmjvtli1m ). The issue is that I can only get 2x8 of the characters working on my LCD, around half of what it should be. It is definitely HD44780 compatible and although the project asks for a 2x16 display I am told that a 2x20 should be just fine.

So my question is why can I only get half of the display working? Here's a picture

Could it be a wiring issue (I have resoldered again just to be sure) or do you think I should try and buy another LCD (which I really don't want to do as this was supposed to be a recycle challenge to myself from scrap parts).

I saw on one of the Pyro projects (infact a few) that the data lines 0 - 3 are not used when wiring LCDs but instead 4 - 7 are. My project shows all 8 on the wiring diagram as seen here

I have quite a big LCD that I am unable to find any data about, it is a 2x20 LCD with MC2002EP-SYL on the board but I cannot find any data about it. Here's a picture for size comparison. Does anyone think that this would be HD44780 compatible?

I really do apologise for intruding, if this post causes offence please delete it, I just thought I'd try!

Graeme

[ThePyroElectro]

Hi. I am so sorry to be posting in your forum but desperate times call for desperate measures, as they say...

So for the last 4 months I have been building a midi electric drum controller from this website http://www.megadrum.info . The project's creator has been helpful, but he is really busy and he has tried helping me with this issue but so far no dice.

That's pretty darn strange.

In my experience if you can write 1 character to the display, the whole thing should work. I know some of the LCD displays are modular and use a single control IC with multiple character RAM IC's that refresh the display. It's possible one of those RAMs died so it can't output properly to the display. Typically if the LCD is going to die, the whole thing dies and nothing works.

The wiring diagram you showed is just connector to connector, as long as whatever you're using to drive that 16 pin connector is sending the proper output signals, wiring should be fine.

The HD44780 interfaces allows for a 4-bit data bus, so you can just tie DB0-DB3 to ground and talk over DB4-DB7. That's what you were seeing in some of the projects.

As for your larger LCD 2x20, I don't recognize the part number and my limited search on it yielded nothing. I wouldn't be surprised if it also uses a HD44780 compatible interface...it's a very universal standard for these character module LCDs. If you can find all the IC part numbers on the back of the controller board it might help your search. Very often they put black epoxy globs over the ICs so its near impossible to figure out what they're using. Very annoying .

[Gman83]

Thanks for the reply!


Ok so in a flash of brilliance I remembered that I have another identical LCD in my workshop, somewhere... I will scavenge for it after work today. I will post my findings if you are interested, I know I am!

You see I have tried to build this thing on nothing but free parts lying around so I really don't want to buy an LCD, but this seems promising...

Thanks!

[ThePyroElectro]

Thanks for the reply!


Ok so in a flash of brilliance I remembered that I have another identical LCD in my workshop, somewhere... I will scavenge for it after work today. I will post my findings if you are interested, I know I am!

You see I have tried to build this thing on nothing but free parts lying around so I really don't want to buy an LCD, but this seems promising...

Thanks!

Yea I'm definitely curious...hopefully you got it working by now.