Well yes, I maybe started to optimistic.
I saw this page https://store.ncd.io/product/cayenne-raspberry-pi-weather-station-kit/
where you can order a Weather Station kit, managed by Cayenne with this short guide:
“If you want to controll your house appliance, sensor temp, humidity, light and monitor power the you can use Cayenne and CE device and build it all by yourself in few minutes.
So let’s say you want to control 8 devices in your house, to do that all you needs is a Raspberry Pi, Raspberry Pi I2C shield and a 8 channel Relay board. All of these device you can find on CE store. To monitor humidity & temp and light you can pick a suitable sensor according to your requirement from CE.
Setting up the hardware is so easy all you need to do is plug the i2c cable and plug the I2C adapter into your raspberry and connect rest of the hardware with your pi. Once all the hardware is connected and powered up for a quick test you can run i2c scan command and you will all those devices listed on your screen.
Now we have all the hardware setup we can login into cayenne and setup the UI according to hardware. CE relay board usages MCP23008 digital IO expander to control and this MCP23008 is supported in cayenne so turning on/off devices using your phone will be a few minute task.”
Of Course I have not order this kit, I have not the same addon boards ordered and an older Raspberry, but it sounds such simple with " Sudo i2cdetect -y 1" and than go to the Cayenne Dashboard and “add New”…
and here I failed, how to pickup the correct “sensor boards” I have.
Have I to add I2C Shield for Arduino Uno as well?
Would be glad, if some could assist to solve my brain puzzle.