Ok, but when adding BMP_280 the dedicated library refused to work, so I have to install the Sensors I2C library (a contributed one, very nice), which has nothing to do with the Adafruit sensors master library. To mount a DHT22 I need to install 2 libraries.

I had bad experience with Adafruit sensors library. Then I switched to a clone of Nano (CH340), because I did not want to use shields and the Nano can be transferred to PCB. Took all my stupidities on board without meowing. My first board was (and is) a genuine Arduino UNO. I read the following: Particle – 18 Aug 16 I am looking for a down-to-Earth opinion, related to the future and availability of the devices, based on experience and/or professional background. The final products are to be used outdoor. I also have some wonderful experience with EEPROM (thanks to you guys - hope you remember me from the summer), which I plan to log the data. Preferred method: I2C (I use the dedicated library and no plans to give up:-)) So far, I mounted: DHT22, BMP280 (that I hate), temt6000, various light and colour sensors (which I found rather tricky).

Shall I move to 3.3 Boards and therefore no 5V sensor in hand? Are they available (or connectable) sensors on 3.3V? Of course I can search the net, but I do not need the commercial info.Shall I keep 5V boards (Nano has nice pins and 5 V are easy to obtain, also an wonderful piece - you reccomanded this one in this forum some 9 months ago - thank very much!).

One problem is that I have to pay attention to level shifting - which I still jave to learn how to. Therefore I have to go for 5V LED Display and 5V sensors.

Adafruit trinket 5v vs 3v