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Topic: VHN2SP30 pullup question (Read 545 times) previous topic - next topic


on the data sheet, figure 4, it says the ENA & ENB must be externally pulled up.  And that is how it's done on Pololu's motor driver board.  All I've ever worked with previously is the L293D.  I usually pulled the enable pin low with a 10K, and then used a 330ohm from a digital pin on my Arduino to pull it high.  This would prevent the motor from running briefly at power up.  Can I do this same thing with these ENA & ENB pins to keep this motor driver from running at startup?

VHN2SP30 datasheet:

Pololu motor driver board schematic:


The Pololu board brings the enables out to the headers - its not clear if it has pull-up or pull-downs on board from the photo.

Yes, thats a good way to do it - use external resistor to define the state of the enable pin(s) while the microcontroller is booting up.
You only need one resistor, your 330 ohm is unnecessary for this purpose.

Adding a 1k or so resistor in line can be useful for protection purposes though - motor controller gets fried, resistor prevents the damage
spreading to the microcontroller.  Make sure the pull-up or pull-down wires to the micro-controller end of any protection resistor though,
avoids creating an unintended resistor-divider.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


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