Post by thread:[EE]: LCDs

I'm testing a bunch of reclaimed LCD screens of indeterminate origin, 16 x1, 20 x 2, 32 x 4 etc. Going well until I went over the handlebars when a 16 x 1 wouldn't display its full 16 characters. It has a single 44780, and there doesn't appear to be a second chip under the glass Whilst tinkering (and making the odd error) with the s/w to try and get something out of this display, I did get chars to appear in the second 8 positions, but don't know if this was accidental and not repeatable under controlled conditions What I think I've understood from the Hitachi manual is a) a 44780 can display only 8 chars of its own, and can store 80 b) it can drive 44100's, each of which can also display 8 chars Can someone please confirm this that so I don't waste any more time trying to get 16 chars out of an 8 char display. Or is there a way to get twice the performance out of a 44780 ? Getting the second 8 to light up accidentally (?) has got me intrigued TIA -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Hiya, It's working fine and I think you've doped out what is happening. Most 16x1 displays are actually 8x2 displays with the lower line concatenated onto the first. To jump to the 9th character, send a 0x0C0 instruction to the LCD to move the cursor to the first character of the second line. Good luck! myke {Original Message removed}

TIA, Sounds like they're working to me. If you need them I've got several data sheets that explain the operation of the 44780. I'll email them to you if you don't all ready have them, let me know. Ken {Quote hidden}> I'm testing a bunch of reclaimed LCD screens of indeterminate > origin, 16 x1, 20 x 2, 32 x 4 etc. Going well until I went over the > handlebars when a 16 x 1 wouldn't display its full 16 characters. > It has a single 44780, and there doesn't appear to be a second > chip under the glass > > Whilst tinkering (and making the odd error) with the s/w to try and > get something out of this display, I did get chars to appear in the > second 8 positions, but don't know if this was accidental and not > repeatable under controlled conditions > > What I think I've understood from the Hitachi manual is > > a) a 44780 can display only 8 chars of its own, and can store 80 > b) it can drive 44100's, each of which can also display 8 chars > > Can someone please confirm this that so I don't waste any more > time trying to get 16 chars out of an 8 char display. Or is there a > way to get twice the performance out of a 44780 ? Getting the > second 8 to light up accidentally (?) has got me intrigued > > TIA > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Hi all, Am just about to lay out a PCB which people will inevitably use to connect to suplus LCDs. see http://www.users.bigpond.com/gzimmer/ Am collecting any and various LCD pin-out information... would appreciate very much any details anyone has to hand.. thanks .............. Zim -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

Hi, Jinx! Well, about six months ago, I have used a chinese "unknown brand" LCD of 16 chars for 1 line. I was surprised because the first 8 characters are in "line 1" position and the remaining 8 in the "line 2". Yes, the LCD has only 1 line, but, who knows why, its characters are organized like 2 lines by 8 characters. If one needs to write characters in the 8 remaining positions, you need to send a command "SET DDRAM ADDRESS" in order to point to the "second" ;-) line. Maybe the code that I have dropped to PICLIST might help you to deal with this kind of display. The code uses this display and the name of the message is something like "PIC16F84 + LCD + RS232". I posted it in august (or september, I dont remember). The attach is a zip file that contains a .ASM . Two versions are posted, one in spanish and other in english. The code works very well and performs a simple terminal with a PIC16F84 plus 4 x 4 matrix keyboard and full duplex 1200 bauds RS232 and, of course, a 16 char by 1 line LCD (4 bits interfaced). I think that this may be help. Cheers! :) {Original Message removed}

From: Alejandro <EraseMEalejolspam_OUTTakeThisOuTADINET.COM.UY> > If one needs to write characters in the 8 remaining positions, you > need to send a command "SET DDRAM ADDRESS" in order to > point to the "second" ;-) line. > > Maybe the code that I have dropped to PICLIST might help you > to deal with this kind of display. Thanks, I've got a copy of that file. I've used 16x1 LCDs in the past without problems, and now that I look at some of them I find they have a 44780 and at least one 44100. This is the first one I'd got that had just a 44780 and it caught me off balance. I'd tried second line addresses but never did manage to get the second 8 chars going on purpose. The Hitachi chip manual doesn't say explicitly that a 44780 can drive only 8 chars, you kinda have to work it out by flipping back and forth between the addressing examples. Getting the second 8 lit up by some accident threw me I'll have another look at your 4-bit s/w when I get around to the 4-bit screens, which have just a single 44780, presumably then these are also just 8x1. I've no idea what they were used in, but obviously a machine that didn't need a full 16x1. As Oliver Broad said, why put a 44100 in if it isn't needed ? -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

The 2nd set of 8 chars is probably mapped at offset +0x40 in the display. Also make sure you set the display size select bit correctly. Use a card fill to fill the entire display RAM and see what maps where (card fill = A,1,2,3,4,B,6,7,8,9,C,1,2,... in this case to catch windows of 8 chars). Peter -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

Thanks for all your input re: the LCD. I've concluded the screen is faulty as the display flickers if you even slightly flex the board, so I've binned it. That's dumpster-diving for you, easy come, easy go. Plenty more where that one came from. All of my old routines are fine on any other LCD except the Acme-brand thing and it just happened to be the only example of its make so I had nothing to compare it to. The EPE reference was a good one - more digestible than the tech-talk Hitachi chip manual and a handy companion piece -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu