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Topic: Uno + Motorshield output issues...a newbie looking for guidance (Read 861 times) previous topic - next topic


Im trying to setup my Uno with the Seedstudio motor shield, I have the sketch uploaded to spin the 3.6v motor clockwise then counter clockwise in ten second intervals. I have a 3.6v litium ion battery hooked up as well. The motor and battery were taken from a black and decker power screw driver. when I plug the uno up to the usb the motor will only hum for the ten seconds but not move? If I wire the motor direct it runs just fine. So in all my question would be, how do I get the power to flow? I am extremly new to this and trying my hardest to learn coding. Any help would be greatly appreciated for this old guy.




The three motor shields from seeedstudio all use a version of the L298 chip.  That chip requires a motor power supply that
is 2.5V above the logic HIGH voltage, so 7.5V.  Anything less and its not guaranteed to work.

Furthermore it drops about 2.5 to 3V across its output transistors so you'd get no voltage across your motor at all!

Its designed for 12V to 40V range really...  Anecdotal evidence it will work at 6V (or even 5V?).
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Thank you for the reply, would it be possible then to just skip using the motor shield and just power the motor off 13 and gnd on the uno?


Unlikely - what's the motor?  does it take less than 40mA at stall?  Have you thought of just adding a second battery to give 7V?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


I did hook up a standard 9v battery to it and it works fine but not for a long period, I understand that the motor plus the board and shield will eat a 9v in testing. My application is very simple just spinning a motor for a set time controlled by a rtc for a door. Thank you again for the reply's I've been trying to learn this on the fly with over twenty years of cnc background and custom macro b programming it gets frustrating at times. What is the best way for me to start to get an understanding of the coding and language?

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