SparkFun Forums

[inventore123]

I'm slowly getting towards these beautiful displays
Currently I've completed drawing the PCB for the connector breakout and the switching power supply (to get +4.6 and -4.4 out of a li-ion battery).
After I receive the PCB (and after I successfully solder the QFN IC that is used to get the 4.6 and -4-4 voltages ) I'll order the displays (the 2.8" with touchscreen, of course 8))

Just a question to silic0re: what are the way of payment accepted by vision opto? Their website doesn't seem to be helpful about that...

[silic0re]

That's great! I have a simple breakout board that I could put up, just for the hirose connector (without a power supply attached).

I actually have to redesign my +5/-5V supply -- the combo buck/boost/inverter I was using to get the +5/-5V from a lipoly would collapse under any sort of load, and I followed the reference schematic exactly. The 3.3V buck/boost works fantastically, though.

Currently I'm just putting the +5/-5V in with a bench supply, but I'd definitely be interested to hear about any success you have with generating those voltages from a lipoly!

---

I should have some information to post on interfacing with the touch screen soon. It's not all that straight forward, there seem to be lots of rotations, translations, and skew-adjustments that one has to do. I *almost* have something working, then I can figure out how to auto calibrate it.

Oh! I almost forgot to mention, vision-opto accepts paypal, which makes them super-easy to order from!

[gussy]

Hey gussy,

You should give vision-opto a try, I recently ordered a small quantity of 2.8" OLED's with the touchpad interface, and they were nothing but helpful through the process.

I have the touchpad sort-of working with an ADS7846 touchpad controller, but so far there's quite a bit of noise in the signal. I have to do some reading on noise reduction in touch screens. I think often (aside from just sticking some filter caps on the lines), the techniques that are used are often in software -- averaging, and other more complicated methods.

I have sent them some emails too. I will see which one can offer the best price for samples and for my quantity (if my project goes ahead), which is probably around 250 units. Being Chinese, vision-opto are probably the OEM, if not closer to them than OSD, so maybe better prices.

I'm slowly getting towards these beautiful displays
Currently I've completed drawing the PCB for the connector breakout and the switching power supply (to get +4.6 and -4.4 out of a li-ion battery).
(...)

Would you mind posting up your schematic? I am interested to see what chips people are using to get the bias voltages.

(...)Currently I'm just putting the +5/-5V in with a bench supply, but I'd definitely be interested to hear about any success you have with generating those voltages from a lipoly!

---

I should have some information to post on interfacing with the touch screen soon. It's not all that straight forward, there seem to be lots of rotations, translations, and skew-adjustments that one has to do. I *almost* have something working, then I can figure out how to auto calibrate it.
(...)

I will probably start with the +5/-5 PSU route, unless I can get a PCB made up before I get the displays.

I am keep to see what you come up with regarding the display. Like you say, once you can calibrate it and write a few maths functions with the calibration constants, it should be fairly simple.

Regarding the noise you were seeing, are you using a breadboard? That could be an issue with the ADC lines.

I assume the touchscreens are resistive, not capacitive? If they were capacitive that would truly make a great screen.


I am also keen to get my hands on some datasheets to see how they suggest you mount to a case...

[inventore123]

Would you mind posting up your schematic? I am interested to see what chips people are using to get the bias voltages.

If you go to Farnell website you'll find these displays. Their price is not interesting (too high) but they have freely downloadable datasheets. On one of them you'll find the +4.6/-4.4V power supply schematic. It uses a chip named NCP5810D which seems designed to drive AMOLED displays. Unfortunately it's a tiny 3x3mm QFN chip, with 12 pins. I searched the web for a more hand-solder friendly IC (or combination of ICs) to get those voltages, but couldn't find anything with proper voltage/current ratings that satisfied me.
So my first attempt will be to try soldering this chip.
I did not make any modification to the reference schematic, and I'll post images if I succeed driving the display with this IC. (Please note that I still don't have the PCB and the display, so it will take some time before I can try)

[silic0re]

Unfortunately it's a tiny 3x3mm QFN chip, with 12 pins. I searched the web for a more hand-solder friendly IC (or combination of ICs) to get those voltages, but couldn't find anything with proper voltage/current ratings that satisfied me.

Those ones are a piece of cake -- you can do them with a standard soldering iron by making extra long pads (about 2/3mm past the part, so you have something to heat up), or by using a toaster oven. I have used both methods.

I am looking for something with +5/-5V, as I am also using the +5v for other things -- but for just the OLED, the NCP5810D would probably work great. I've noticed my OLED screens can get pretty hot if they're plugged in without being initialized for a while (they just display this pure white). Maybe it has something to do with me sticking in a bit too much voltage...

[gussy]

Vision-opto came through. Very easy to deal with.
I just sent payment for 2x 2.4" and 2x 2.8" displays.

I haven't even heard from OSD yet, so it looks like I will just forget them.

Vision-opto's prices are quite good. Sample price for the 2.4" and 2.8" displays, both with touchscreens is $22.6 and $27.5 respectively.
Price in quantity is not that much cheaper, $1-3...

I am going to design up a carrier board with the NCP5810D for +4.6 and -4.4 voltages and an ADS7846 for the touchscreen controls. I haven't decided if I want to breakout all the pins or just the ones for SPI yet. I may just do a full breakout.
I also need a 3.3v boost/buck switcher in there, any suggestions?

I should have the carrier board designed up within a week or two, no idea when I will actually get it made and play with these displays though.

[silic0re]

That sounds great, and like you're having some success!

For a 3.3V buck/boost, I used a TPS63001. So far I've had nothing but good things to say about it -- it's very small (about 3x3mm), requires only one external inductor and some filter caps, and has a feedback line on it so that the voltage remains pretty stable.

The serial lines are great to play with for a first tinker, but if you want some serious speed I think you have to go for parallel. If it doesn't add too much to your design, I'd definitely include a header for parallel access.

[gussy]

I have finished the schematic for an SPI carrier board, just need to layout the board. From what I see in the app notes, it would be kind of difficult to make a breakout for both SPI and Parallel. I may just make a new breakout if/when the time comes...
(I will post up the schematic/board when its done, to share and also get a second pair of eyes on it.)

The project this will be going into first is a simple remote sensor display device. All it needs to do is display a few numbers/buttons and a graph. If I can get 5hz that would be great, but the underlying fact of why I am going to use SPI is because the data only comes in at 1-2hz, so the screen will really only need to be updated at 1-2Hz, which should be a piece of cake for the SPI interface.

Parallel needs 18 data lines and then a few more right? About 24 from what I count. That's about half of the LPC2148's I/O pins. I probably have room for that in my design but it may well be overkill.
We will see I guess, that's the point of testing isn't it

Thanks for the tip on the TPS63001, I will have a look into that.

My displays are on their way, but I am not sure how long it will be until I get around to hooking them up, may be a month or more, but I will post back if/when I have success

(On a slightly off topic note)
Big OLED's are expensive!!
I asked vision-opto, out of curiosity, prices for the bigger OLED displays, they start at $60 (3.4") and go all the way to $500 (7.6") as samples.
2.4" and 2.8" really do seem like the sweet spots at the moment.

[emile_b]

Nice work!

What connectors are you using for the displays? I cant see any information on the website, nor even anything very useful in the datasheet...

[emile_b]

Ah, found it.
I thinks its:

fh23-61s-0.3shw

www.hirose.co.jp/cataloge_hp/e58613007.pdf

..for those interested.

The vision-opto site is not very well constructed!

[silic0re]

What connectors are you using for the displays? I cant see any information on the website, nor even anything very useful in the datasheet...

I think the connector information is in the datasheet? This is the one that I use:

http://search.digikey.com/scripts/DkSea ... FQ461CT-ND

The pitch on the cable is 0.3mm, but it's 0.6mm on the connector it alternates which side the pins are broke out to. It's not too bad to solder with a fine-tip soldering iron at all, if you've soldered some small pitch SMD stuff before. I'd recommend getting a few, having at least one to practice on.

[gussy]

silic0re, what is the connector for the touchscreen?

I am yet to get the datasheets I requested off vision-opto, they just sent me info on what colours are best and something about gamma...

[lucap87]

I too have recently bought a display from Vsion Option. I took the 2.8-inch thoucscreen.

The connector I have found in Farnell One link.

I was thinking of developing a open source driver for SPI.

[gussy]

I too have recently bought a display from Vsion Option. I took the 2.8-inch thoucscreen.

The connector I have found in Farnell One link.

I was thinking of developing a open source driver for SPI.

You must be Lucas from lucasproject.it who ordered some samples in early Febuary?

Sorry I couldn't help myself.
Vision-opto managed to somehow reply to one of my emails with their reply plus a whole string of correspondence between yourself and vision-opto.

I am really keen to see someone come up with a decent graphics library for this display. Open source sounds really neat.

What hardware are you using?

[lucap87]

Yes I'm Luca of lucasproject.it.

Not yet beginning to plan anything. I would use a generic hardware, perhaps to start a PIC32 might be sufficient.

I would like to develop such libraries for a project with a client, but with time I feel a bit long.

I'm thinking of adding the display to a linux system like Fox Board.
but I have yet to buy the connector and make a demoboard, unfortunately it takes a long time to achieve.