Small graphics LCDs

On a sunny day (Sat, 08 Sep 2012 23:41:42 -0400) it happened Phil Hobbs wrote in :

I got some nice ones from ebay = China, item 190466776198 datasheet:

In use in my gamma spectrometer: That whole thing runs on 2 AA rechargables for 8 hours. I wrote the LCD graphics driver in PIC 18F14K22 asm, you can have the source if you think it helps you ;_) It is for the die-hard programmers. It has AFAIK no character generator, so I wrote that too, some rotation could make you think about string theory :-)

Get a display that has a controller supported by a ready library. Getting all the bits and pieces correct, lines drawn and fonts working really is not rocket science, but may take quite some time from doing the rocket science part.

I've used Ramtex with their font editor. No complaints, took a few hours to get working with my hardware but after that the LCD handling was really easy. And changing the LCD has no effect on the actual code now.

I once selected a greyscale display that actully used RGB controller. That meant data being handled in 3 byte groups and speed really sucked on ready drivers. Using 3n (9/12/15) pixel wide fixed width fonts with my own code fixed it.

--
Mikko OH2HVJ

s s

seems many are using LCDs from nokia phones both color and monochrome, spi interface and lots of code around

a google for nokia lcd will give plenty of hits

-Lasse

A branch of this, once you get the basic screen library setup, is to code up the font map(s). There may be FOSS solutions (haven't really looked, lately) but an inexpensive commercial generator is BitFontCreator Pro over at . It's really pretty easy to use and greatly simplifies the effort.

I've used it on a few projects and am happy with it. It takes care of generating the required C code for the bitmaps, width, and jump tables. Also makes using proportional (i.e., not fixed-width) characters relatively straightforward.

There was a long discussion over in comp.fonts some years ago about the legality of using bitmaps derived from copyrighted type faces. I don't think that we ever came down to a globally satisfactory answer, partly due to the different ways that the issue is addressed in the EU versus US. An cautious work-around was to use an FOSS family such as Liberation as the basis of the bitmaps.

--
Rich Webb     Norfolk, VA

This is jes a lead, more than a recommendation. I've mixed feelings about the vendor, but there is a tutorial of sorts (scroll down).

nb

--
Definition of objectivism:
"Eff you!  I got mine."
http://www.nongmoproject.org/

Thanks, all.

What's a good BOM estimate for ~100 of these? Surely it has to be less than the distributor's third column price, which is $12-$18 for this sort of device.

Any preferences for controller chips?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Hey what do people think about these OLED matrix displays?

I was put off last time I looked - a few years ago now. Seemed to be poor lifetime, burnt pixel problems and the apparent habit of vendors to exit the business. Is this still a fair concern?

--

John Devereux

Some of my old IBM friends worked on OLEDs for some years. The technology is very pretty, but some of the materials used are not what you'd expect--there's a _metallic_calcium_ electron emitter layer.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

Funny, toobs use "alkaline earths" for cathodes too, just a little warmer ;)

A useful column of the periodic table, I guess -- electronic structure (bandgap, fermi level, work function, etc.) should correlate with junction potential into most solids. Unusual to use with semiconductors though!

Come to think of it, anyone know offhand what alkaline earths do to silicon? I know sodium ions move around in the oxide, making MOSFETs hysteretic or memristive, but I've never heard what the effect of alkaline earths, or rare earths for that matter, is.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Calcium metal is used as the getters in tubes.

Metal in silicon is usually bad news.

My Dad used to work for Cominco back in the '70s, when they were the major supplier for ultrahigh purity gallium and arsenic for GaAs wafers. They had a guy in the seven-nines gallium facility that really liked eating potato chips, and didn't always remember to wash his hands....

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

I heard barium, but that would work just as well I think. I've also heard of magnesium, but that seems less efficient.

But not always -- I know transition metals generally add mid-bandgap levels which act as recombination centers, gold and platinum being the most common. In this case, the advantage and disadvantage are the same effect: more energy levels means avalanche occurs easier, but it also means shorter recombination time. 7400 was fairly fast as bipolar circuits go, but it also broke down at only 7V, while contemporary bipolar circuits operated at 30 or 40V (7V could also be due to stronger doping; I haven't heard if the two families were acutally made on the same process or what).

I know copper is bad, for the same reason (though I don't know how it differs from Pt or Au when lifetime killing is desirable), though it's not an insurmountable problem, as ICs with Cu interconnects are being made now.

IIRC, Pt-Si schottky junctions are the most common combination used in schottky diodes. Breakdown is low and leakage is high, but that's expected for the device; it's not so much a disadvantage as simply an understood aspect of the technology.

Also in ICs, high-k gates are being made with HfO2, IIRC. Another transition metal, though on the farther side (nearer to Ca and whatnot!), don't know what it does as an impurity.

Can't think of any other elements I've heard of. I'm sure they've tried them all at some point, and most just kind of suck, or don't do anything, or don't do it as well as others. I just don't know which ones! :)

Whoops, that'll bump off a couple nines!

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

I know the folks who developed the copper back-end process (the leading light was Dan Edelstein, who's a pal of mine). The trick was figuring out how to pattern copper, because it doesn't RIE well at all, and wants to diffuse all over the place. They eventually came up with the dual-Damascene process, where you etch the dielectric where you want the wires to be, put down blanket liner metal and blanket copper, then polish back to the dielectric surface. (You have to encase the copper completely in the liner, or it gets loose. Nasty gooey crud, copper.) They used plating to get the thickness needed for the upper (fatwire) metal levels. Everything depended on the very different polishing rates of copper and dielectric, which gave them really accurate control of the process. Magic stuff.

Platinum silicide gives nice repeatable junctions--it used to be commonly used for IR focal plane arrays, because its excellent uniformity of response made up for its horrible quantum efficiency, which was only a couple of percent IIRC.

There was also a guy in one of their lead smelters who refused to wash his hands before eating his lunch--he got big black smears of lead concentrate on his sandwiches. He had some weird metabolic peculiarity and never showed an elevated lead level, despite being tested every month for years. Having him around made it twice as hard to get the other guys to be careful about lead ingestion.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

Might be worth looking here:

--
Using Opera's revolutionary email client: http://www.opera.com/mail/

Since after all, if you can RIE it, you can just chuck it in with all the other processes -- perhaps with different etch gas and whatnot, but the hardware's the same. But hey, polishing is a standard process too, and, I'd guess with a dash of ammonium persulfate, or nitric acid or something like that in the lubricant, it should easily rub off whatever copper stands out, since SiO2 isn't going anywhere under those chemical conditions. A gentle enough abrasive will do the same thing.

Wandered onto glass solders the other night. Compositions include Pb, Zn, B, Si, P and other oxides, various mixtures to control softening point, crystallinity, wetting; additives and fillers to control strength, TCE and so on; neat stuff. Interesting that Zn is often used, but Cu is not; Zn often has different electronic structure from Cu, so I can see that working. I suppose Zn should be a "P2" type dopant in silicon, but maybe its energy band is a little too far to be practical.

Yuck! That from the shallow junction width?

Geez! Now, I know lead sulfide isn't very soluble, but I don't know how that goes with stomach acid. At the very least, a pH around 0 is going to knock a few zeros off the K_sp. Lead is supposed to mimic calcium, so I wonder what kind of metabolic peculiarity could do that -- calcium is involved in just about every other ion channel in the body, and an abnormality could do rough, systemic things. Hmm, should be more than a few known diseases due to genetic abnormalities of calcium channel proteins and stuff, could be interesting reading...

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Chem-mech polish is fairly deep magic, as far as I'm concerned--there are a lot of process dimensions that don't exist in ordinary etching. I did a bit of CMP myself, back in my tunnel junction days, to make planarized SOI waveguides. Si/SiO2/Si3N4 is a relatively easy CMP problem, but you still have to use a carefully designed fill pattern to avoid dishing. (Dishing is overpolishing in areas where there's too much of the easily-removed constituent, oxide in this case.)

Hmm. The glass solders I know about are minor variants of the age-old frit bonding process, i.e. dielectric rather than metal. Telcordia has standards for them, I think.

I don't know why it is--I've never heard a good discussion of PtSi focal planes.

I don't know--he might have had acid reflux, and popped a dozen Tums a day, or something like that. I'd expect enough calcium in your diet to do a good job of preventing lead uptake, assuming you didn't get kidney stones. (Stones are probably still better than lead poisoning, but by all accounts they are _not_ fun.)

Truth is still much stranger than fiction.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net