I'm not sure whether you're asking if I'm using the Nano and Uno simultaneously or if you're asking if I'm connecting all the ground pins on the MCU together externally, but the answer is no in both cases.
I'm not sure whether you're asking if I'm using the Nano and Uno simultaneously or if you're asking if I'm connecting all the ground pins on the MCU together externally, but the answer is no in both cases.