My circuit Consists of:

Output of voltage regulator (5V) is connected to motor shield screw terminal (Vin,Gnd) and motor shield passes the power to Arduino. Both Arduino and Motors are powered with 5V.

After connecting power to input of voltage regulator Arduino Yun flashes green LED and shuts down. This happens about 50% of the times. In other cases Arduino starts up properly and circuit is working as expected for hours.

What could be the cause of Arduino shutting down fraction of a second after connecting power? When I powered separate Arduino Yun witch micro USB phone charger this problem didn't happen, but with motors and shield I need too much current for powering with microUSB. The voltage regulator I use is quite reliable i think.


I attached capacitors for decoupling, but it didn't help. the circuit looks like this: circuit of arduin yun controlling motors

  • \$\begingroup\$ Do you have sufficient decoupling? \$\endgroup\$ – Ignacio Vazquez-Abrams Oct 9 '13 at 15:46
  • \$\begingroup\$ Did you actually measure the 5V rail? To check if your board is OK, detach all peripherals and just power up the board by itself. If that works and it starts to fail when you connect other stuff, you can figure easier out what is happening. \$\endgroup\$ – jippie Oct 9 '13 at 16:33
  • \$\begingroup\$ @Ignacio, After the problem occured I added capacitors on the input and output of voltage regulator - 47uF and 10uF respectively, but it didn't help at all. Should I use capacitor on motor shield output too? \$\endgroup\$ – PanJanek Oct 9 '13 at 16:59
  • \$\begingroup\$ @jippie, I measured voltage regulator output and it was 5.1V \$\endgroup\$ – PanJanek Oct 9 '13 at 17:00
  • \$\begingroup\$ Does it only happen when the motors are connected? \$\endgroup\$ – jippie Oct 9 '13 at 17:02

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