jbdiver

OLED displays

89 posts in this topic

So being in Australia, TME not having any Raystars in stock, my local company being dodgy, First charging me 70eu postage,and Rapid declining my credit card means I'm still on the hunt for a replacement display. It appears TME have yellows and whites from a company called Display Electronik. Again, they appear to be the exact same display as the Raystar and Winstar, yet they want nearly 20eu more. 

http://www.tme.eu/en/katalog/?id_category=112917&used_params=1134%3A59300%3B1140%3A356437%3B

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I recently got some white Raystar OLEDs and am having trouble getting everything to work right.

When I have the power at 3.3v, both displays start up fine but as soon as it loads the Seqv4 app it immediately reboots. If I start up with only 1 LCD connected at a time, the boot sequence works just fine.

When I have the power at 5v, the Seqv4 app loads fine but only the left display functions correctly - the right one shows some random characters.

I have set the LCD type to 0x02.

I have tried powering both with USB and external power. Is this maybe a current draw problem?

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Could you please provide a link to the datasheet of this display?

Best Regards, Thorsten.

 

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I have an email out to the company. Unfortunately they do not seem to have detailed electrical specs on the datasheet or website.

http://www.raystar-optronics.com/products-category-detail.php?lang=en&ProID=296

The part# is REC004002AWPP5N00000. 

Code system here: http://www.raystar-optronics.com/down.php?DID=6 (triggers download of PDF)

It appears to be 5v, but current draw is not clear

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Hopefully it will be possible to find a more detailed datasheet.

Maybe it isn't related to current draw, but to a configuration option.

This is based on speculation, but worth to check (because I've no other idea): according to the website this display supports different protocols such as 6800, 8080 and SPI.
The 8080 protocol is required, if 6800 is selected instead, a short circuit would happen between the parallel connected data busses during read operations, and this could cause a malfunction (e.g. core reboot)

With some luck you will find some bridges on the PCB which show the configurable options on the silk screen.

Best Regards, Thorsten.

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What a timely coincidence. I'm repairing my SEQ atm and have the exact same issue. I have Winstar OLED's which are the same component as the Raystars. Here's the datasheet.

I've replaced a fried MB997C Discovery board with a brand new one labelled MB997D. I haven't changed any jumpers on the core board. OLED's are set to 3.3v. The result is the same if I run over USB or 5v direct power.

One OLED attached shows fine. Two just come up blank or the left one shows a few odd characters. Wasn't there a trim pot contrast adjustment thing at some point in the build or am I thinking of a differenet project?

Edited by mongrol

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something is different from the Winstar parts, I have those in mine and changing to 0x02 did the trick.  Had the same issues with one not working.

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@mongrol was the OLED working before?

I just tested a MB997D with two common CLCDs - they are working (tested with MBSEQV4)

Best Regards, Thorsten.

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2 hours ago, TK. said:

..

Edited by Altitude

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@tk. Yep, these Oled's were perfect before I b0rked by discovery board. I'd forgotten about the 0x02 though... so...

  1. Uploaded boatloader_update app
  2. Set lcd_type 0x02
  3. Store
  4. Reset
  5. Looked back in my enclosure thread and checked my previous voltage for my oled's (it's clear it's 3.3v on the pic).

Both screens still won't work at the same time. I remember having a helluva time when building this first time around and somehow in my build thread I came up back to 5V and 0x02. However, every photo I look back it it's clearly set to 3.3v.

Time for more oxygen I think.

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@mongrol Thanks for the datasheet! Based on that, the Raystars operate at 5v.

@Altitude & @TK. Yes, I think you are right in that it is a jumper. There is a spot marked J68 J80. It was factory set to J68. I changed this to J80 and now both LEDs will operate at the same time, but they are not displaying anything resembling the correct characters and do not update after the Seqv4 has started

IMG_20161111_190606.jpg

IMG_20161111_190825.jpg

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Hmm, my Winstars also have a jumper set to J68 (the pcb is exact same as the Raystars) but previously I had both working fine (after a lot of kerfuffle). Off to dentist, will change jumper when back.

Buffoon Edit: I don't have Winstars at all. I have one Raystar and one Midas.

UltraBuffon Edit: Now I don't have any oled's. Changing to J80 gave me the same odd chars as Jarvis but I broke one in the process. Then doing more elimination broke the other one. Bums, cheapo LCD's for me from now on. Oled's are too much hassle.

Edited by mongrol

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I suspect the PS and SHL may be relevant here as well but I am far from a display expert to have any input on those

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Hola, potentially it is a power-related problem...

Can you check for clean power on the 5V rail? E.g. with an oscilloscope?
I am using two OLEDs as well in my "flatsequencer mbseq v4" (i think with the power set to 5v) and i get trouble with screen garbage after a while, most likely due to a noisy (cheap) switching regulator i am using to bring down the battery power from about 9.6v to 5v.

If you are using 3V to drive the displays and are using a STM32F4 core, the tiny onboard-regulator of the STM32F4 may be overloaded, imho it also only provides 3.0V, not 3.3V and the displays require 3.3V? Can you check the 3V supply voltage of the displays during operation? Voltage? Ripples? Sometimes a medium-sized cap (470uF) over the supply pins is sufficient to stabilize the OLED.

Edit: sorry, just read that they are broken now, sorry. How did you break them?

Many greets,
Peter

 

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One of them broke when I was removing cable. My cables are on angled pin headers to fit my enclosure and the little copper coil thingy close to the pins broke off as it was tight to the IDC socket. Tried to repair and replace it but too small and fiddly for my big ol'beef fingers. The other broke when I was changing the J80 jumper back to J68 and the pad came loose. Again, big ol'beef fingers.

So right now I have a choice. Go with some LCD's which isn't exactly plugnplay as I have backlights to deal with, or go with more Oled's. I've found RS sell Vishay brand for about $30 USD each (cheap or what!) and again, appear to be identical to Raystars.

What I don't get is how I had them working flawlessly before. 1 Raystar and 1 Midas, running off 3.3v with the jumper at the the default J68. 0x02 in bootloader and both displays worked everytime. Now I've replaced the core with a newly flashed one it all stopped giving me joy.

I have another choice. Sell the SEQ parts off and be done with it. :|

Edited by mongrol

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Nah, don't sell the SEQ parts, my recommendation: get some cheap 40x2 LCDs from China first and start jamming. You'll love the SEQ, there is always a chance to upgrade/repair later on.
If you want bling, you could also go for VFDs, loving mine since 2010, they are absolutely awesome and I'd prefer them over the Raystar OLEDs every time ;-). Of course, the best ones from Noritake are expensive as hell! ;-). So, visit your local trustworthy china outlet and get some cheap displays first, upgrade later ;-)

Have a great rest-of-the-weekend!
Peter

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Yeah fair enough. I'm having a grumpy day. :) Pulled my old Midirex out to get some jamming done and it kept hanging on me too. Just one of those days where nothing goes right. Although I do like these days in that they put things in perspective in how much "stuff" I have to maintain.

Will get some cheapo buydisplays and see how we go. Least I get 6 weeks piano practise waiting on them arriving. :D

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For my situation, I have determined it was in fact a power issue. I added an extra regular for the OLEDs which draws directly from the external power supply in order to bypass the built-in regulator on the STM32F4 Discovery board, and it now everything works correctly. I have also set the lcd_type to 0x02 in the bootloader. 

So, in order for the Raystar OLEDs to work correctly, they need to be fed 5v and to be externally regulated. I wish I had exact specs for current draw, since this means the OLEDs are drawing more current than cheap LCDs they replaced. It might also be that this specific color variant draws more current than the others. In my case, I am using white on black OLEDs. The OLEDs look and refresh significantly better than the cheap LCDs they replaced, so I see it as worth the extra effort.

FWIW - I would not recommend these white on black LCDs from buydisplay.com - the refresh rate is terrible and there is significant bleed from the backlight

Edited by jarvis
Clarification

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3 hours ago, jarvis said:

FWIW - I would not recommend these white on black LCDs from buydisplay.com - the refresh rate is terrible and there is significant bleed from the backlight

*facepalm*

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So I now have new Oled's. These are Vishay's and cost $103 AUD for 2. MUCH cheaper than the Raystars and seemingly identical.

https://au.rs-online.com/web/p/oled-displays/8812731/?sra=pstk

Now to get them working I did this.

  • Set to 5V
  • Left the J68/80 jumper on the oled's to J68 (default)
  • set lcd_type 0x02 (in bootloader prog)

583e93298e608_Vishayoled.thumb.jpg.32b9b

That was it! As soon as I "store" after setting the lcd_
type they came up correct.

Now. RS sent me yellow's when on their webbie they have greens. The bags had the green RS part number but the Vishay Yellow part number on them. I thought about returning then gave up as I'm certain they'd send me more yellows and I'd be months without a Seq fighting the system. :)

Edited by mongrol
Oled RS snafu

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Hmf, well that didn't last long. Once everything had heated up a bit after a few reboots it stopped working. Right Oled shows fine, left shows gibberish. If I switch to external 5v power it's worse with gibberish on both.

Oddly enough when I load the bootloader they both work fine, switch back to the SEQ application and it's misbehaving time again.

Going by the above I think I need one of these regulators? https://www.adafruit.com/products/2164

 

Edited by mongrol

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How did you set the Core LCD voltage jumper?

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Maybe try 3V/3V then, this would load the Vreg a bit, but apparently only to 60mA. Could be noise on your USB 5V buss?

 

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