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I am currently working on a automation project consisting of 3 analog sensors and 2 dosing pumps using a Raspberry Pi 3 B+. I am powering the sensor and motor modules using one 12v 5A power supply to provide external power and have its ground share with the Pi. A simple block diagram of the configuration can be somehow represented as shown below:

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The motor module consist of 2 L298 motors which can be used to drive 12V motors which are inline with my specs. The sensors are also powered with the 12v to power a MB102 supply to provide 5V and 3.3V for the analog and digital sensors. I've already configured the sensor module with controller. My question lies on how I should correctly configure the motor module to avoid noise due to ground loops since I plan to power the modules in parallel from the 12V using a cable splitter.

Can I connect the ground from the motor module to the sensor module and have the return path from the motor module to the Pi go through the sensor module ground? If so, would it be fine if the return path goes through the MB102 coming from the motor module? Or should I have a separate ground connection for the motors between with the Pi and the 12V power supply?

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    \$\begingroup\$ You do not want your sensors and Pi in the high current path of the motors. Wires have resistance and thus voltage drop. A star connection might be more appropriate. \$\endgroup\$
    – Kartman
    Commented Feb 16, 2022 at 1:27

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As Kartman says, a star configuration is desirable here so you can avoid having motor currents flowing through signal grounds. The same applies to power rails but since you’re using 12V for the motors I’d hope that the MB102 will keep the low voltage supplies safe from any transients

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  • \$\begingroup\$ I just wanna clarify if my understanding is correct. That would mean two GND connections between the modules and the pi right? One GND between Pi to sensors, and another from Pi to L298 motor driver while the two modules share the 12 V? \$\endgroup\$
    – Guorishix
    Commented Feb 18, 2022 at 5:07
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    \$\begingroup\$ Kind of. Pick one earth point and connect all the earth returns directly back to that point, no earth connection should go directly from any other point to another point. \$\endgroup\$
    – Frog
    Commented Feb 18, 2022 at 9:12
  • \$\begingroup\$ Oh alright. Thanks! \$\endgroup\$
    – Guorishix
    Commented Feb 19, 2022 at 0:08

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