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Hi!
They say there is nothing worse than a free gift as you end up paying for it multiple times.
Well I say it´s even worse when you decide to do this to yourself.
So I was browsing ebay the other day and I decided that my next little project would have an oled display, nothing serious just to torment myself for fun and gather some exp..
I came across this nice little thing: https://www.ebay.com/itm/0-91-0-91in-White-Blue-OLED-Module-Display-IIC-Interface-128x32-SSD1306/142831922310?ssPageName=STRK%3AMEBIDX%3AIT&var=441833372791&_trksid=p2057872.m2749.l2649
Everything seems to have something like that inside nowadays, from toaster to soldering iron, so why not kill some time trying to program it, find what makes it tick and so on and so forth.
From what I gathered it was using a SSD1306 chip inside, or at least a knock-off controller like that one, made from pure chinesium. Good stuff! Good times!
Since most of the blogs documenting it and "ready to use" modules were either configured as SPI or I2C, I said great, I really don´t like coding for I2C but I love SPI, so that´s great!
After some weeks product arrives and I try to find a datasheet! (BTW I am still looking for one so if anyone has a link, please feel free to help :-) )
And what I find out leaves me so dumb-fu€ked that I try to let out my frustration in this post.
There are 2 versions of it. One 14pin and one 15pin... 15pin version supports both protocols, 14pin version is only i2c and of course I got this one.
Why? How can this be any cheaper in the end? It is probably a question of which clone came first but still... why?
You go through the effort to clone the shit! Why? Just why...
I kinda don´t what to wait more for me to play around, then again, I feel kinda bored trying to do my own PCBs, so I might as well design and order...
I´ll see, whether or not I force myself to go through writing a proper i2c library or order the also SPI enabled part. I know the adafruit library exists, what did I tell you earlier though?
So well... it´s one thing being careful of what you order and another this being true evil...
Best Regards,
Lefteris -
Well it *does* say it is i2c and says nothing about SPI so I don't really get what you are complaining about, you got exactly what you ordered.
I honestly wouldn't bother with taped version and just get one like that
https://www.aliexpress.com/item/1-3-inch-White-OLED-Module-SSD1106-Drive-IC-Compatible-with-SSD1306-IC-128-64-IIC/32653191275.html
Note the resistor to change bus type. -
Well it *does* say it is i2c and says nothing about SPI so I don't really get what you are complaining about, you got exactly what you ordered.
Cause it takes a special mentality to produce the same product with a 14pin and 15pin version tape, the second one having both protocols, just with this extra pin that costs absolutely nothing more.
Ebay listings ain´t always that accurate, especially for stuff like that, and you go by the controller.
And in the end of the day I am not complaining... I am just amazed and keep wondering...I honestly wouldn't bother with taped version and just get one like that
https://www.aliexpress.com/item/1-3-inch-White-OLED-Module-SSD1106-Drive-IC-Compatible-with-SSD1306-IC-128-64-IIC/32653191275.html
Note the resistor to change bus type.
Well brah... we are not on the same page of that chapter, I stopped playing Jenga with Chineseum bricks years ago...
I come from the long forgotten years back when parallax was the only thing available through a 56K modem...
I learnt how to design and build cause it was a necessity, not a choice.
But I acquired the basic mentality needed to become better cause of that. Trying to find out how stuff works and not just bombard myself with info.
And even for something as tedious as a display, it´s always better to go through with your own design. Repetition makes perfect... wax on... wax off... wax on... wax off... and so on...
Best Regards,
Lefteris -
Are they same chip tho ? Maybe the I2C only version is made using 3c micro but the I2C/SPI one required 4 cent micro ? Or they saved a bit on tape cost. Chinesium optimisiation to its finest
I'd normally agree but in that case you'd just end up with same thing that is soldered back on chinesium board, and just having "an i2c with power" connector on your device allows for swapping for different module in case this one goes out production, or source changes and "same" OLED display needs a bit different voltages.I honestly wouldn't bother with taped version and just get one like that
https://www.aliexpress.com/item/1-3-inch-White-OLED-Module-SSD1106-Drive-IC-Compatible-with-SSD1306-IC-128-64-IIC/32653191275.html
Note the resistor to change bus type.
Well brah... we are not on the same page of that chapter, I stopped playing Jenga with Chineseum bricks years ago...
I come from the long forgotten years back when parallax was the only thing available through a 56K modem...
I learnt how to design and build cause it was a necessity, not a choice.
But I acquired the basic mentality needed to become better cause of that. Trying to find out how stuff works and not just bombard myself with info.
And even for something as tedious as a display, it´s always better to go through with your own design. Repetition makes perfect... wax on... wax off... wax on... wax off... and so on... -
I'm kinda confused, surely the 'I2C' in the title should have given a bit of a clue that it is, y'know, an I2C interface?
Seems a little unfair to complain about the quality of the seller or item if you ordered the wrong thing. -
I was unaware the 15 pin version does I2C and SPI. I've only ever used the 15 PIN with SPI.
Do you have a link to the data sheet that shows how to get it into I2C mode?
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I was unaware the 15 pin version does I2C and SPI. I've only ever used the 15 PIN with SPI.
Do you have a link to the data sheet that shows how to get it into I2C mode?
They pretty much seem to be knock offs from these Vishay modules:
https://www.vishay.com/docs/37894/oled128o032dlpp3n00000.pdf
I don´t really have any other details on these modules. -
I'd normally agree but in that case you'd just end up with same thing that is soldered back on chinesium board, and just having "an i2c with power" connector on your device allows for swapping for different module in case this one goes out production, or source changes and "same" OLED display needs a bit different voltages.
And for some things especially for testing purposes I would strongly agree, but usually if you used OLED displays before, their DC/DC converter is noisy as fu$k...
There are still reasons you might want to roll out your own board, even for playing around, believe me :-) -
There are still reasons you might want to roll out your own board, even for playing around, believe me :-)
Nothing wrong with that, of course. At least you get the chance to apply the double-sided sticky tape yourself and mount the display at a right angle!
I am pretty sure I have seen subtle variations of the flex cable pinout on these, beyond the I²C only vs. I²C/SPI versions. These differences might have been between different "compatible" clones of the controller; can't recall the details I'm afraid. So it is better to get a datasheet (or at least the pinout) from your actual seller than to assume anything. Otherwise you could end up with another "rinse and repeat" cycle once you have designed your PCB... -
This product seems to be based on the same type of OLED display. Documentation for both the OLED module and SSD1306 controller
https://learn.adafruit.com/adafruit-oled-featherwing/download -
Nothing wrong with that, of course. At least you get the chance to apply the double-sided sticky tape yourself and mount the display at a right angle!
One of the things that actually got me into buying the part rather than the "module" was that I wanted to use a connector :-)
But I guess I´ll have to do that for the 15pin version of the board just for flexibility reasons
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I met those OLED so far only in I2C, didn't know they come in SPI; since they are small and there are not many pixel to set - only in one color additionally, I2C seems more than enough, although I prefer SPI too - so I do prefer the bigger sized TFTs
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It takes a special stupidity to design with a part without reading its datasheet.
Who designed what? I was just on a ebay spree... The thing cost me not even half a cup of coffee
Only when I started looking for designing the thing, I found that out.
The SSD1306 comes in 3 possible connections, no matter the panel size. 8bit parallel, SPI and I2C. 8bit parallel is a bigger connector so it´s out of the question.
But since whether or not it works in SPI or I2C is determined by single pin for the 15pin version, why would you design a I2C only 14pin version?
From what I got from the SSD1306 datasheet, you have to have the CS pin tied to low to access the I2C which is broken out in the 15pin version.
Or else you can use it in 3pin SPI mode, according to the datasheet and the broken out pins on the flex.
Plus the 15pin version gives you a rudimentary control of the I2C address so that you multiplex two displays.
So no, I don´t really get it. Even in the million parts having one assembly line rather than two can cut costs down.
But thank you for the schematics anyhow, they will come in handy!
Best Regards,
Lefteris -
It doesn't make any sense if you design a module for general purpose application, but it makes good sense if you tailor a modle to your particular needs.
And I can truly understand it, but just like many IC products the 15th pin could be described as a N/C or test lead "must connect to ground" pin.
It shouldn´t be a space limitation either, thingy is pretty tight already.
But what I am thinking is that it was probably a connector pricing thing. Especially early oleds were really unreliable and have burnt pixels only after hours of operation.
What if people actually used in their products connectors for these? I remember seeing them tied to connectors some years back and also the flex ending supports a connector (has anchor points).
So what if the 14pin connector was much more produced and much less expensive than the 15pin connector? I´ll go have a very basis look around!
But that makes sense.
Best Regards,
Lefteris -
So I made a bit of research and results are inconclusive at least from my side.
I was looking for 0.5mm pitch connectors with either 14pins or 15pins.
I looked at both mouser and digikey (which are both not the cheapest sources) but more as a test sample.
Mouser had a better pricing for the 14pin connector, digikey had a better pricing for the 15pin connector.
I don´t know about Asian market suppliers though, but I would guess more material more cost, if they have access to tooling for both parts.
Dunno... really dunno... But it would be interesting to find out, just for shits and giggles! -
On a related note, why on earth are all these cheap modules blue? Blue OLEDs have terrible life spans, while amber or green lasts practically forever.
Also, I've had terrible luck with SSD1306 controllers in I2C mode; they're flaky as all out and will randomly lock up for no apparent, discernible or fixable reason. Maybe it's just the cheap knockoffs (e.g. "1106"). It has no correlation to bus speed, signal integrity, commands or data sent, specific operations, timing of back-to-back operations, etc - they just flake out for absolutely no reason. So, personally, I would recommend staying away from these cheap I2C interface OLEDs. The SPI ones seem to work better.
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I still don't see access to the BS0 BS1 BS2 pins on this 15 pin version of the module that are needed to select I2C mode. So don't know why it's assumed that you can do I2C on them.
And I'd really like to be able to access I2C on a 15 pin module, so if I'm missing something obvious I'd appreciate some specific details.
Also, regarding connectors.
These cheaper modules are not meant for connectors. Just hot bar (or equivalent) soldering attachment.
There are versions for FPC connectors.
I recommend the following supplier.
https://www.buydisplay.com/default/oled-display/0-91-inch
A good dealer, with support and documentation with examples for what they sell. Probably the same as Far East Rising company.
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Also, I've had terrible luck with SSD1306 controllers in I2C mode; they're flaky as all out and will randomly lock up for no apparent, discernible or fixable reason.
I had project with SSD1306 in I2C mode and I2C EEPROM device on the same bus. The display was constantly refreshed (~5 times per second), in the meantime EEPROM was read from time to time.
After 5 minutes to 5 hours of OK operation, the I2C become "locked" with SDA net held down by display. Completely removing the EEPROM reading code and then EEPROM itself - so that display was the only device on bus - didn't help.
What did help though, was detecting the lock-up state by watching bus collision in I2C master status registers, once the lockup happened, disabling I2C master, bit-banging more (up to 9) SCL clocks and watching the SDA state after each bit. Once it was released, I performed start-stop condition on bus and I2C master could be started again.
With this "kludge" * it worked flawlessly, I have no clear idea what was the problem, though. It was my personal project, so I was OK with that. I wouldn't release commercial product like this.
* it is not that much of a kludge - see https://www.nxp.com/docs/en/user-guide/UM10204.pdf chapter 3.1.16 Bus clear -
But since whether or not it works in SPI or I2C is determined by single pin for the 15pin version, why would you design a I2C only 14pin version?
Likely because the 14P version came out first, maybe custom ordered by a manufacturer, then the design got cloned everywhere before someone decided to add SPI support.
Most likely so.
And anyway, as someone else said, that was clearly stated in the eBay title that it was an I2C module. (Yeah you guessed it: IIC is I2C). And the shown pinout has only 14 pins and shows nothing else than SDA and SCL for communicating.
The rest was just all guessing.
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On a related note, why on earth are all these cheap modules blue? Blue OLEDs have terrible life spans, while amber or green lasts practically forever.
From what I got they ain´t blue, all models are with white LEDs just "painted" over with various colors.
I mean they ain´t painted themselves, the polarizer I think is. -
Also, I've had terrible luck with SSD1306 controllers in I2C mode; they're flaky as all out and will randomly lock up for no apparent, discernible or fixable reason.
After 5 minutes to 5 hours of OK operation, the I2C become "locked" with SDA net held down by display. Completely removing the EEPROM reading code and then EEPROM itself - so that display was the only device on bus - didn't help.
I´ve worked with a different kind of OLED display before, they were from Winstar with a WS0010 controller inside. The DC-DC converter inside was terribly noisy.
Have you thought of separating the supply of the DC/DC converter of the display from its Vcc line? What you are describing is a classic microcontroller lock-up scenario. -
These displays are ultra common in the Arduino and RPi realm - adafruit have links to the chipsets
https://learn.adafruit.com/monochrome-oled-breakouts/downloads
https://www.adafruit.com/product/931
There easy to code - I have built a few projects inc a boost gauge what did both text and bar graph (1.3" 128x64)
Quality is very hit and miss but I got a good batch from a uk supplier -
It's not the first time I see stupidity like that. Cheap modules are not always let you use full potential of the parts. This is typical for knock-off of knock-offs. It's also not always possible to clarify specification as sellers often have no clue what they sell.
If you want good quality buy genuine parts from adafruit, sparkfun, etc, but I'll pay much more... Which still makes sense as time is often more expensive than saving every penny. -
A lot of components are graded what supplier one doesn't want someone else will snap up, if your prototyping a design the cheapest isn't always the best method but if your going to make a batch you need to find a trusted supplier, not some random company selling what ever they can get down the Shenzhen market along with there car dvd players and women's clothes
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I´ve worked with a different kind of OLED display before, they were from Winstar with a WS0010 controller inside. The DC-DC converter inside was terribly noisy.
There's no obvious noise coming back. Trust me, I know how to look for problems. There may be noise on the module, or inside the controller, but that's not really fixable.
Have you thought of separating the supply of the DC/DC converter of the display from its Vcc line? What you are describing is a classic microcontroller lock-up scenario.