I am using an arduino and device with separate power sources, 12v to the arduino and 5v to the device. They are communicating using I2C, do I need to tie the grounds?
Why not power the arduino with 5v? Which arduino do you have.
12v to the arduino
That's the VIN voltage one assumes, presumably the Ardiuno actually runs at 5v (or is it 3v3?).
Either way you have to have a common GND.
Mega2560, on an octocopter that I'm doing a custom flight controller and custom software for. I've got a 12v bus that connects four batteries 8 ESCs and has two 12v general use outputs, one of which is powering the arduino mega. The ESCs each output 5v and 2 amps, they are all tied into a common bus with multiple general use output connections powering an array of sensors and devices including my IMU which communicates through I2C. In this setup there is no common ground between the 5v bus powering the IMU and the 12v bus powering the controller. I guess my question goes for the devices using TX/RX lines as well; does there need to be a common ground between communicating devices powered by separate sources?
If it were me I'd just power the arduino from the 5v as well. Also would tie the grounds together anyway.
That's the VIN voltage one assumes, presumably the Ardiuno actually runs at 5v (or is it 3v3?).
Either way you have to have a common GND.
Thanks! I'll go a head and tie the ground lines of the two buses.