We are using GPIO pins on this board: Fusion 1-Channel SPDT Relay Controller with 16 GPIO or ADC and I2C - store.ncd.io
The connector pinout is :
In a very simple LED circuit, would I be need to use the GND pins on this GPIO connector, or should the LED simply be connected to the same GND used by the source providing power to my Fusion board? Would both approaches work?