I am creating a circuit with several sim00l connected to different UARTs each with its own external power. But I'm curious if having other objects like cooler-fan connected to other GND of the rpi would not affect the functionality of my sim800l regarding what is known as ' floating ground or FG'. Here is what I plan to implement https://ibb.co/KXxCXFf. In the same way I would like to know if my common ground connection between sim800l and rip4 would work De Thank you. enter image description here

  • you must have a common ground, unless you use opto-isolators ... your configuration looks ok ... how is the RPi powered?
    – jsotola
    Apr 29, 2022 at 15:10
  • Thanks, I am powering the rpi with an external power supply (5V and 3.0 A). Apr 29, 2022 at 15:48

1 Answer 1


Well friends if the circuit worked, is more I edited it by changing the lipo battery power supply for power regulated with lm2596 and a 4700uf capacitor for each sim800l module. Thanks

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