With raspberry pi1 (the 2011 model) the screen are working but not with omega that not recognize them.
I will probably resell my omega and various accessories because the assistance is not very helpful :-/

@Michal-Dobrzynski Please do not forget to remove the pin3-pin4 short circuit if you want to plug the Oled Expansion to any genuine Onion Omega Expansion Board Header directly because Omega2(+) may be damaged if you set GPIO11 to Low.

There are I2C level shifters on the OLED Expansion.
Pin4 of the Expansion Header provides the voltage to the lower voltage section for those level shifters.
But pin4 of the Expansion Header is connected to GPIO11 on the Omega2(+) board.
So @Onion must set GPIO11 to High (~3.3V). It's a hidden simple hack that @Onion forgot to mention for example here.
You could find some further technical details here.

@Maximilian-Gerhardt Thank You.

I have been fighting against an error where it looked like the linker was not finding my the shared libonioni2c.so. Your suggestion about first renaming the current files /usr/lib/libonioni2c.so to /usr/lib/libonioni2c.so.XX and /usr/lib/liboniondebug.so to /usr/lib/liboniondebug.so.XX was a good suggestion.

My error changed to libonioni2c.so not found. So it shows me the linker was finding the correct shared object but there was something wrong with that libonioni2c.so share object. then I copied the shared objecs from github https://github.com/gamer-cndg/omega2-libs and put them in /usr/lib and everything worked!!!

2 weeks I have wasted.

Now I don't know what is in those shared objects or what is different but at least I can continue building my project.

From my 2 weeks of trying everything I have concluded that the shared object libraries provided in the standard distribution for the 2+ libonioni2c.so and/or liboniondebug.so are defective.

Sorry, my fault :-) 194 is ok!

Thank you @György-Farkas for detailed answer.
I've tried this ADC (on demo board) on Arduino and also received nothing.
I think that this board is broken.
I bought ADS1115 and now I can smoothly read from photodiode :)

If somebody will need that in future guys from Control Everything Community made working python example for Omega2.
(or at least it's working in my case with FW: 0.2.0 b191)

@Lazar-Demin Great to see it working. If you need a gateway you can also use a ESP8266 NodeMCU board with another RFM95 module and configure and flash the https://github.com/things4u/ESP-1ch-Gateway-v5.0 firwmare on it, also see http://things4u.github.io/. Needs a little bit of fiddling around with the configuration and pinout; Also be aware that the EUI of the TTN gateway must be the one that the firmware spits out on startup (it's made up of the ESP8266's MAC address and two 0xff in the middle).

you can try this python lib
https://github.com/bhaskar-anil429/MCP9600/blob/master/MCP9600.py
or this c
https://github.com/bhaskar-anil429/MCP9600/blob/master/MCP9600.c
You can replace i2c read write with onion syntax.

@Aurélien-Fi At the end of the day, the MT7688 chip in the Omega2 is really targeted in in a router, access point, or similar. It's good at connectivity (Wifi AP and client, ethernet), but not at things like cameras or displays.

The chip in a Raspberry Pi is the opposite - note that a Pi Zero doesn't have any way to connect Ethernet, but has HDMI, a camera interface, and USB device support.

My point here is that different processors have built-in hardware support that will make some things easier than others. The Pi Cameras are only so cheap because of the dedicated hardware in Pi.

So, this isn't something the Omega2 will be really great at doing. That said, there are ways. The main issue is one of bandwidth - I2C isn't that fast, so I'd look at SPI, UART, or especially USB. I think the Omega2S even breaks out PCIe, which opens lots of possibilities.

The little Arduinos don't have much connectivity for cameras either, so solutions for them might work out. For example: http://www.arducam.com/arducam-mini-released/

@György-Farkas

Many thanks!

@Maximilian-Gerhardt wow! Thank you very much for your response, at least I don't have the feeling like I'm shouting into an empty cave!

I'm surprised at how beta the i2c library is for something that's been out for ~years. I feel like the first feature for boards like this (after GPIO control on its own pins) should be a matured and robust i2c library. Since, almost anything you want to do with them will require i2c communication...

Again, thank you for the heads up with known issues. I'll try to keep stumbling through this and if I succeed I'll make it available.

@OSO-Bear Judging by the output of the program and your makefile, it looks like your program was compiled for x86 (your computer). You'll have to use an xCompile.sh script like the example to cross compile your C program.

PS it's three backticks to open a code block, and three to close it. See this link for more markdown syntax.