lcd4linux-devel

Re: [Lcd4linux-devel] [lcd4linux] Sharp LM40001G LCD

[Till H. <ti...@ha...>]

Hi,

400*64 pixels is quite nice. Under lcd4linux this would basically
be a 66*8 character display.

> Maybe some of you also have interrest in a cheap size-DOES-matter Graphic
> LCD, so we could share some of the development work.
Don't get me wrong, but 22*3,5 cm this is not THAT big :-)

> Interfacing it seems a bit of troublesome, as it doesn't contain a
> framebuffer, so all data has to be sent continuosly.
So does the ledmatrix display, so you might be able to do something
similar to its driver. 400 x  64 is 25600 pixels which in turn is 3200
bytes. This does not fit into the memory of any of the small avrs,
so you either use a mega128 (with 4k ram) or use an external ram.

Ciao,
  Till

I just returned from the IFA fair and LG as well as the german Telekom
hat some very funny presents: Small fans that have 7 leds on one of
the two wings and display some text while running. I'd really love to
build one of those and make a lcd4linux driver for them. DIY instructions
for similar devices can easily be found with google when searching for
led rotor display or similar. E.g.:
http://hackedgadgets.com/2006/06/13/top-5-spinning-led-displays/

-- 
Dr.Ing. Till Harbaum <ti...@ha...>
http://www.harbaum.org/till

Re: [Lcd4linux-devel] [lcd4linux] Sharp LM40001G LCD

[Michael R. <re...@eu...>]

Hi there,

>>> Interfacing it seems a bit of troublesome, as it doesn't contain a
>>> framebuffer, so all data has to be sent continuosly.
>> So does the ledmatrix display, so you might be able to do something
>> similar to its driver. 400 x  64 is 25600 pixels which in turn is 3200
>> bytes. This does not fit into the memory of any of the small avrs,
>> so you either use a mega128 (with 4k ram) or use an external ram.
> 
> Yeah, probably some sram chip from an old '286 Mainboard, got plenty of those 
> left.
> Then probably a pic18f4550, maybe ATMega16.

Well, I'm afraid this won't work that easy... from a quick glance over
the datasheet, it looks like the display consists of row and column
controllers only, but no real lcd controller.

These row/column drivers are controlled using a serial protocol, which
is a) high frequency and b) very timing critical. Thats what a lcd
controller is for.

If you really plan to build an interface, you should really consider
using a SED1550 or similar controller.

Wolfgang, are you listening? Your opinion?

> With enough ram it would also be possible to implement two different greys.
> Keep two framebuffers, display them alternating, keep one "on screen" a little 
> longer than the other (If the display timings allow that)
Again, I'm afraid this won't work, probably because of the "slowness" of
the LCD display.


bye, Michael

-- 
Michael Reinelt <re...@eu...>
http://home.pages.at/reinelt
GPG-Key 0xDF13BA50
ICQ #288386781

Re: [Lcd4linux-devel] [lcd4linux] Sharp LM40001G LCD

[Ernst B. <e.b...@xe...>]

On Wednesday 06 September 2006 06:52, Michael Reinelt wrote:
> Hi there,
>
> >>> Interfacing it seems a bit of troublesome, as it doesn't contain a
> >>> framebuffer, so all data has to be sent continuosly.
> >>
> >> So does the ledmatrix display, so you might be able to do something
> >> similar to its driver. 400 x  64 is 25600 pixels which in turn is 3200
> >> bytes. This does not fit into the memory of any of the small avrs,
> >> so you either use a mega128 (with 4k ram) or use an external ram.
> >
> > Yeah, probably some sram chip from an old '286 Mainboard, got plenty of
> > those left.
> > Then probably a pic18f4550, maybe ATMega16.
>
> Well, I'm afraid this won't work that easy... from a quick glance over
> the datasheet, it looks like the display consists of row and column
> controllers only, but no real lcd controller.
>
> These row/column drivers are controlled using a serial protocol, which
> is a) high frequency and b) very timing critical. Thats what a lcd
> controller is for.
>
> If you really plan to build an interface, you should really consider
> using a SED1550 or similar controller.

Hrmm. The original controller board has a Z80 CPU, a Z80 UART, Ram, EPROM with 
Os, an "Character Generator" EPROM, more Ram, a 7.3728 crystal, and a larger 
TTL graveyard.

I think it generates its pixel data with dual 74166 shift registers, and does 
all the character generation stuff in TTL. Hard to say more about it without 
schematic.

And since the pixel clock is only at about 500kHz (800uS for a line, 2uS for a 
pixel, 1/(2*10^-6)=500kHz, it should be possible to implement in an uC, maybe 
with help of two external shift registers.

Gotta test if shifting in software can be fast enough, unfortunatly those uCs 
only have one USI/MSSP that could help here.


> Wolfgang, are you listening? Your opinion?
>
> > With enough ram it would also be possible to implement two different
> > greys. Keep two framebuffers, display them alternating, keep one "on
> > screen" a little longer than the other (If the display timings allow
> > that)
>
> Again, I'm afraid this won't work, probably because of the "slowness" of
> the LCD display.

Yeah, probably. Since it would be "just" software, it can't hurt to try. If it 
doesn`t work, nothing lost.

/Ernst

Re: [Lcd4linux-devel] [lcd4linux] Sharp LM40001G LCD

[Ernst B. <e.b...@xe...>]

On Tuesday 05 September 2006 23:35, Till Harbaum wrote:
> Hi,
>
> 400*64 pixels is quite nice. Under lcd4linux this would basically
> be a 66*8 character display.
>
> > Maybe some of you also have interrest in a cheap size-DOES-matter Graphic
> > LCD, so we could share some of the development work.
>
> Don't get me wrong, but 22*3,5 cm this is not THAT big :-)

Well, sure, it doesn't compare to your LEDMatrix, but to be correct:
it has a 22.6x4.3 cm viewing area, which still beats the usual case-modders 
4x20 lcd hands down.

> > Interfacing it seems a bit of troublesome, as it doesn't contain a
> > framebuffer, so all data has to be sent continuosly.
>
> So does the ledmatrix display, so you might be able to do something
> similar to its driver. 400 x  64 is 25600 pixels which in turn is 3200
> bytes. This does not fit into the memory of any of the small avrs,
> so you either use a mega128 (with 4k ram) or use an external ram.

Yeah, probably some sram chip from an old '286 Mainboard, got plenty of those 
left.
Then probably a pic18f4550, maybe ATMega16.

With enough ram it would also be possible to implement two different greys.
Keep two framebuffers, display them alternating, keep one "on screen" a little 
longer than the other (If the display timings allow that)


> Ciao,
>   Till
>
> I just returned from the IFA fair and LG as well as the german Telekom
> hat some very funny presents: Small fans that have 7 leds on one of
> the two wings and display some text while running. I'd really love to
> build one of those and make a lcd4linux driver for them. DIY instructions
> for similar devices can easily be found with google when searching for
> led rotor display or similar. E.g.:
> http://hackedgadgets.com/2006/06/13/top-5-spinning-led-displays/

That "sounds" like a cool hack. Will probably be the loudest display ever 
connected to lcd4linux ;)


/Ernst