I'm assuming (no way to verify) that when the motor pulls too much I get voltage spikes which cuts out my microcontroller. Here's my circuit, any suggestions on how to fix this issue?

The left chip is an hbridge and the center one is a 5v regulator.

enter image description here

  • 2
    \$\begingroup\$ Please show us a schematic. A picture of random wires going to unidentifiable IC is of little use. \$\endgroup\$
    – Matt Young
    Jan 4, 2015 at 16:29
  • 1
    \$\begingroup\$ yes, a circuit. It could be a rail regulation issue or a noise issue (esp with that layout) \$\endgroup\$
    – user16222
    Jan 4, 2015 at 17:54

2 Answers 2


Separate the microcontroller DC supply from the motor supply, with a schottkey diode and a large capacitor on the microcontroller side. This should allow it to ride out short voltage dips on the main supply.

You should do this before the 5V regulator, then the microcontroller will have a completely stable DC supply.


it is a very common problem, this happens when your motor draw too much current from the circuit that microcontroller doesn't receive enough power to turn on... This can be avoided by using a separate dc supply for motor and microcontroller or by using a motor driver.. please refer this thread to get a complete explanation for this :

Isolating motor control signals from microcontroller from high voltage/current lines


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