Maybe you need to update the bootloader and/or fuses? Maybe it has a brownout setting of 4.3V?

http://www.ladyada.net/learn/avr/fuses.html

@vladimir Yes, you could probably use an optocoupler to read the LEDs without taking too much power from them.

@vladimir I have very little time these days so I won't be able to help in detail but if you want to use my method you will need to open your kettle and see what type of buttons they are. They will be connected to ground or power. When you know that you can choose the correct mosfet and start testing. Take a look at my wiring diagram to see what I've done.

@mortenvinding cool! I looked at a couple of code "sniffers" when I did this but none of them worked. Good to hear progress has been made on that. Should save quite a bit of time.

@lis610 Awesome! Congratulations and great job for not giving up. That was a lot to tackle for a first project! Nice enclosure to house everything. Looks way cleaner than mine

@lis610 It should work at 8MHz. Have you double checked the wiring? Did you try with the default sketch in the DHT library? What are the debug messages saying?

@lis610 Great news! I echo what @hard-shovel said. I try to supply my 5v sensors with 5v power from a regulator (with the appropriate capacitors) instead of my Arduino.

@hard-shovel Thanks for the help.

@lis610 You are picking a very advanced project to start with. If you have the time I'd suggest an easier project like a motion sensor to get started. If you want to keep going I'd suggest doing some additional reading/watching on how this all works. Not trying to be critical but rather save you frustration.

I'm not running UI7 on my Vera so I haven't tested but it should automatically create your device as long as you are including it when first starting the node. For me I press the "Start" button then power up my node (the fan in this case).

However, if you don't have good communication it may not add correctly.

@lis610 if it can't communicate with the gateway and controller the node will never get to the loop which could be why the display isn't working. The SPI include used to be required for MySensors.

@lis610 sorry, I'm not a place where I can look in depth. It looks like your code isn't communicating with the gateway though. Did you try the line of code above? The device should work with the push button even if it can't communicate with the gateway (with that code).