Using Aruino Digital pins after putting on a motor shield


So before I go out and buy this motor shield, I was wondering how I could access the digital/analog pins after the motor driver is attached since the motor driver covers up the origional pins. Would it be the same if I use the corresponding pin attached to the motor shield or would the motor shield have altered it somehow? For example, I have a motor shield to power 1 motor. But 1 motor only takes up 2 pins. There are many more unused pins now covered up by the shield. If I also want an LED, well now all the pins are blocked.

I was going to buy this motor shield


As a matter of modern-day-principle you should look away from a motor driver board (shield or otherwise) that uses the L298 chip and look towards (for example) something like this. Far more efficient (the 298 drops at least 2V, up to 4+ iirc at high current), much smaller footprint, and doesn't need a heatsink the size of an elephant.

I am by no means a very experienced arduino user... but I have used an MP3 playback shield in the past whilst simultaneously using an ultrasound was 3 years ago.... but I believe the unused pins on the shield can be used, and will 'pass' your signal straight through to the arduino beneath?

Please can someone verify this as correct? :~

Thanks Twogan

What you say is true Twogan, for some shields.

But look at the pic in the link in the OP's first post. That shield brings the pins out in Grove connectors, making it not as simple a matter of just jamming a wire into a hole.

In general though, pins not used by a shield are indeed available for use, just that in this case the connection is a bit more tricky.

Hey thanks for responding!
The “grove” connector were confusing me when I saw them.

So I need to control the motor (linear actuator) in both directions with 12V, 2-3A.
Do you think the motor driver can do that?
I would imagine you’d need three pins to control a motor both ways to reverse the magnetic field of the coil but that motor driver only has 2 pins?

I read the description of the pololu driver and it says that it can do 1.2A continously at <12 volts but then it says “Motor outputs can be paralleled to deliver 2.4 A continuous (4 A peak) to a single motor”. I’m not sure what that means. Does it mean to say their 1.2A is comparable to 2.4A as the motor is running?


They mean you can use both pairs of output to drive one motor, thus doubling the capacity.

But I only posted that as an example, because I've used it.... have a look around Pololu and see what else they have, to check there's enough current available.

And no, in general you only need two pins: a H/L from Arduino to the motor chip will output a H/L and thus "forward", while a L/H will drive the motor in "reverse".