Hi,
I'm making a weather station for my greenhouse. I'm using an arduino Yun with sensors for in the greenhouse. The yun will send the values to a google drive document. I also use an arduino mega with sensors outside the greenhouse and actuators such as controlling the water supply and temperature.
The arduino Mega will need the values from the arduino Yun. Is it possible to use the UART serial communication to send the values from the Yun to the mega while also sending the values with wifi to the google drive document. Or are there other possibilities? I have no experience with communication between arduino's so help is welcome 
Kind regards
Pieter
Hi, welcome to the forum.
Yes, serial communication is possible. You might need SoftwareSerial on the Yun, and perhaps some protection is needed when using long wires.
Other possibilities are an Ethernet Shield or wifi shield for the Mega, and use that to communicate with the Yun.
Also wireless modules can be used.
For long cables (say 20 meters or more), the serial communication could be done with RS-485.
These are all good options, there are many more possibilities. It is even possible to use the Yun USB host connector and use USB cable to the Mega and connect that to it's usb connector. I'm not sure there is a driver for the Mega in OpenWRT, so perhaps you have to use a seperate usb-serial adapter for the Mega.
Thank you very much for your answer!