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Re: using character LCD as display.

Jeremy,

You should be able to direct your standard output to the serial port
easily, but what will be your input?  (The Linux gurus can step in
here!)

It would be cool to create a Linux driver that drives multiple LCDs off
the printer port a-la Nick's method.
Just a minor correction to Nick's comments: the 44780 is limited in the
number of characters it supports, so larger displays expand with
additional slave chips called a 44100 (also from Hitachi).
I have a display here that's a 4-line unit with 1 @ 44780 and 3 @ 44100
chips on the back.

Hitachi's chips became a limiting factor in LCD module production about
10 years ago so various Taiwanese and Korean manufacturers make clones
now, but if you locate the data for the 44780 it will apply to almost
all LCD modules made.
I have a fairly recent version of the Hitachi LCD Controller Databook
(July 1985) but nothing in soft-copy.

Brian

Jeremy wrote:
> 
> ok gotcha, but my next question is can I
> configure linux to use a Character display
> say on a serial port... by default?
> 
> -----Original Message-----
> From: Brian Empey, P.Eng. [mailto:]
> Sent: Tuesday, March 18, 2003 11:28 AM
> To: 
> Subject: Re: using character LCD as display.
> 
> Character displays have a parallel interface (they all use clones of a
> Hitachi controller developed 20+ years ago).
> 
> You can use 8 or 4 data bits, there is one address line (command/data)
> one direction line (read/write) And a data strobe.
> 
> It is VERY easy to interface these to a printer port.
> The READ function is only used to poll the busy status, so you can tie
> it to WRITE mode, use only 4 data bits, and connect the address/register
> line to another data line.
> Thus, with 5 data lines and the printer STROBE going to the LCD STROBE
> you have connected the LCD to any device with a parallel printer
> interface.
> Just be sure to add a delay between characters since you can't read the
> busy signal.
> 
> I did this back in the 80's ... probably have the code on 5" floppy
> somewhere........
> 
> Any device with serial or USB has an additional circuit board in there
> for translating (which will add to the cost).
> A 2x16 large character (1/2") STN with backlight and wide-temp range
> should cost you US$10- or less in low volume (under 1k pieces).
> A similar display in TN, normal temp, no BL is about U$5.50
> (STN LCD is higher contrast than TN -- [super-]twisted nematic liquid
> crystal display)
> 
> Brian
> 
> PS: NO, you cannot connect your VGA signal to a character display.
> Sorry.
> 
> Asher wrote:
> >
> > "Jeremy" wrote:
> > >Has anyone out there used a Character LCD as a display.
> > >
> > >Anyway I was looking at something like:
> > >http://www.matrixorbital.com/products/lcd4041.htm
> > >could be put in a project box and strapped to my arm for
> > >travel.
> >
> > I've used some similiar displays from Scott Edwards Electronics [1] for
> > projects at work and they work well.
> >
> > >I do a lot of hiking and am working on a hiking website...
> > >just thought a wearable could help me take notes and
> > >keep track of way points, etc etc.
> > >
> > >the LCD has a serial interface... anyone ever concert
> > >VGA to serial?
> >
> > This'd be really tricky, you'd need a system running OCR software
> > looking at the VGA video! Far easier to design your user interface
> > device so that it can be hung off a standard serial port - the serial
> > display can be directly connected, and it's pretty trivial to make a
> > simple keyboard that can transmit serial data. Then you'd just need a
> > suitably tweaked termcap entry and getty or similar running on the
> > serial port.
> >
> > Asher.
> >
> > [1] http://www.seetron.com/
> >

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