Use this with a 100 nF across the motor terminals (right on the motor). Also make sure you have good ground connections to a common grounding point near your power supply. Isolating grounds means you have floating signals to your H-Bridge. That is not good.

Also, add a ceramic 100 uF in parallel with each cap shown.

Reviving a dead horse, but I wanted to say that this helped my problem.
You can see my scope traces before and after in this thread:
http://forum.arduino.cc/index.php?topic=366489.0

 

Reviving a dead horse, but I wanted to say that this helped my problem.
You can see my scope traces before and after in this thread:
http://forum.arduino.cc/index.php?topic=366489.0

I can't see your new circuit there.

 

I can't see your new circuit there.

Maybe it doesn't work when using a smart phone.
Either way, here's the link (I'm only using the green portion of the circuit)
http://forum.allaboutcircuits.com/attachments/image-jpg.60753

 

Maybe it doesn't work when using a smart phone.
Either way, here's the link (I'm only using the green portion of the circuit)
http://forum.allaboutcircuits.com/attachments/image-jpg.60753

Hi UncertainPrinciples,

Thanks for sharing.

To answer your question in Arduino forum. I think your motor draw too much current at start up, and it pull the voltage too low for the arduino to work properly.

In your circuit, the diode on the right and the 10uF cap act as a local power supply to your Arduino. When your motor starts, it draw a lot of current and pull the voltage of your power line down. But the diode only go one direction, even your power line is pull too low by the motor, it can't effect the voltage on your 10uF cap. The 10uF cap keep powering your arduino until the motor starts and power line rise back to normal voltage. Hence it stop the resetting.

And I don't think you need the diode on the left, it just wasting power sitting there.

 

Hi UncertainPrinciples,

Thanks for sharing.

To answer your question in Arduino forum. I think your motor draw too much current at start up, and it pull the voltage too low for the arduino to work properly.

In your circuit, the diode on the right and the 10uF cap act as a local power supply to your Arduino. When your motor starts, it draw a lot of current and pull the voltage of your power line down. But the diode only go one direction, even your power line is pull too low by the motor, it can't effect the voltage on your 10uF cap. The 10uF cap keep powering your arduino until the motor starts and power line rise back to normal voltage. Hence it stop the resetting.

And I don't think you need the diode on the left, it just wasting power sitting there.

Hi Bug13,

Thanks for the explanation. So the (right) diode is to prevent the motor load from taking from the 10uF capacitor then. Ahh that makes sense.. Thank you.