Hello,
bought different SSD1306 Oleds 128x64
First of all using Adafruit Lib on Pro Mini 5V A3/A4 for SCK SDA - this works for one of the Versions.
Second display Version didnt work - displays strange things.
Differences i can see
Elliptic holes vs round
VCC 1st pin vs VCC second pin
PCB designs different
Any tips to get also the "elliptic" holes version working?
SSD1306 displays are 3.3V devices. They may work with a 5V Arduino Board. They will work with a 3.3V Arduino Board or with a 5V Board together with a voltage level shifter (resistors or 74HC4050).
Oliver
Edit: For I2C (Wire.h) the 74HC4050 wll not work. The 74HC4050 will only work for SPI.
So which Resistor Value for VCC ans which for SCL,SCA?
I thought it is a SPI communication. You can do the level shifting for SPI with resistors or HC4050, but both solutions will not work with I2C. Actually voltage level shifting is very complicated for I2C due to the bidirectional nature of the bus.
My suggestion is to use a 3.3V Arduino Board (MKRZero or Arduino Due).
Oliver
The Display is according to the ebay description 3.3-7V.
Because i can see something - there is at least the first line which is working correct - it seems init and also sending something works.
But cant understand why 4/5 of the display is always white with single black dots.
Using 10k pullups changed nothing.
These far east I2C OLEDs contain strange resistors on the PCB. Some will work, others will not work.
From my personal experience, all these OLEDs work with 3.3V Boards. With 5V Boards, they may or may not work. I had both cases in my lab. You could try to use U8g2 Software Emulated I2C, which might help. It may also help to test with different voltage levels at VCC.
There are special ICs for this purpose (like this: https://www.nxp.com/docs/en/data-sheet/PCA9515.pdf) but these kind of resistor magic what we have on these inexpensive boards may or may not work. Adding a PCA9515 would obviously too exensive for the OLED supplier.
Oliver
Thanks for your support - and also for the nice lib.
Found a similar problem- but this guy got a note maybe its not SSD1308 could also SH1106 - tried this ... works
Lost many hours because of troll ebay description. Second time i got different items as ordered.