Hello, I'm soldering a PCB circuit, with an arduino Nano.
I would like to know if we can link the GND of a module i2C with the 9V power supply battery.
For a question of solder proximity.
or we'll have to use the GND PIN of the arduino.
Thank you for your help.
What I2C module?
How is it powered?
What does this mean?
For a question of solder proximity.
Can you post a schematic or at least a block diagram.
In general all grounds need connecting together so there needs to be a path for the current to flow for all modules and other parts in a circuit. Using small rectangular 9V batteries is a poor idea because they are expensive and will not last long in an Arduino project. Typical they will not last longer than overnight.