Circuit design - placement of the power switch

I have an X86 computer and an Arduino microcontroller attached to one battery. The grounds of the two devices are connected so they can communicate with each other via i2c. We are using your high powered motor drivers connected to the Arduino. At times we want to shut down the motors and we don’t want any voltage applied to the motor driver pins when the motors are shut down, so we want to shut the Arduino down at the same time.

Our thought is, on the X86 side, to run the power from the battery to a switch and then to the X86 computer. On the Arduino side, we would do the same thing and run the power from the battery to a switch and then to a power bus that powers both the motor diver and the Arduino. Among my concerns is about the X86 inadvertently powering the Arduino side through the connected grounds when the Arduino switch is off. We feel if the switches are on the positive side, we are ok because with the grounds connected, you would also need the positive side to create a circuit on the device that’s turned off… So my question is whether you have any advice re the setup and whether I should put the switches on ground or the positive side of each switch?



Arranging the switch on the positive side is probably preferred over the ground side since you are intending on powering them independently, and a common ground would make the system simpler. However, you should be able to use the SLP pins on the motor driver shield to turn the motor outputs off. Is there a specific reason you want to turn off the whole Arduino?

  • Jeremy

Thanks Jeremy. The only reason we want to turn off the Arduino is to ensure that we never accidentally turn off the motor power and leave the Arduino is running. Good point about the SLP pin. I can’t believe I forgot about that. We added a slide switch connected to the arduino to toggle the SLP pin of the motors high and low. That’s how we will stop the motors. But I think we still need to the main switch to turn the arduino and motors off to shut down the system when it’s not being used. Thanks for the help.