Arduino ProtoShield - tie two separate GND together?

Development Boards Arduino
1

Hi all

I am planning to use an Arduino Protoshield attached to an Arduino and connect a FTDI USB-to-serial (such as the FTDI Basic Breakout) to the Protoshield.

The hookup guide recommends cutting the 5V jumper on the back to avoid conflicting voltages from the FTDI and the Arduino, see section “Software Serial UART Port” in the hookup guide.

What about the GND from FTDI, though? Can I tie together GND from FTDI with GND from the Arduino? The FTDI and Arduino are both connected to USB ports on the same PC (or hub), but can I be certain that they are both at the same potential?

many thanks
Benoit.

2

All GND’s should be connected together, there will be no conflicts.

3

Thanks YellowDog for your reply!

I was measuring 40 mV between GND on the Arduino pin and GND on the FTDI pin and was worried that I might introduce something undesirable when connecting these two GNDs together.