Motor Shield - Jumper Question
Moderators: adafruit_support_bill, adafruit

Motor Shield - Jumper Question

by wgheller on Sat Nov 24, 2012 5:29 pm

Just received the motor shield and installed on my Arduino Uno v3 board.
I pulled the jumper off the PWR pins as suggested in the FAQ http://www.ladyada.net/make/mshield/use.html.

When I power up the Arduino board using USB or the 9v Adapter - the shield is powered up as well. At this point, I have not supplied any external power via the EXT PWR connectors

When I run a sample sketch to control one of the motors, I see the voltage changing at the output connectors as a result of the code (I have not actually connected a motor yet). But I've still not connected any external power and the jumper on the motor shield is not in place.

Is that the expected behavior? I thought that the shield would not draw power for the motors from the Arduino when the motor shield's jumper was removed.

Assuming that the shield is functioning as it should, If I start supplying external power to the shield via the EXT PWR connector, do I risk damaging the shield or the board?

Thank you.
wgheller
 
Posts: 3
Joined: Sat Nov 24, 2012 5:05 pm

Re: Motor Shield - Jumper Question

by adafruit_support_bill on Sat Nov 24, 2012 5:48 pm

When there is no motor supply connected, it is normal for some current to 'leak' through the H-bridge from the 5v logic supply. Sometimes it is even enough to illuminate the green power LED. This is nothing to worry about.
User avatar
adafruit_support_bill
 
Posts: 30867
Joined: Sat Feb 07, 2009 10:11 am