Hello,
I'm working on a PCB heater that is powered from mains and is controlled via an ESP32. (I'm the guy from the mosfet post)
I've never made a device powered from mains that also has a USB port (ESP32 programming), and I was wondering if the two grounds can be simply connected together, or special care needs to be taken.
I attached the schematics (look at power and usb section), in essence:
Mains 230V --> AC/DC brick (12V) --> Switching voltage regulator (3.3V) --> ESP+CH340+USB
The USB port will be connected to a PC or anything that can read a serial port.
The 5V of the USB is not used, so the pins are left floating, but the ground pins are connected to the GND plane of the circuit.
My understanding is that there needs to be isolation when you are dealing with earth to avoid creating ground loops, in my scenario however, the enclosure of this device is 3D printed and the brick doesn't have any connection to earth ground, so I'm only dealing with Live and Neutral from mains.
Can I connect the USB Gnd to the same Gnd coming from the AC/DC brick or do I need to take special care of that?
Thanks