Datasheet

What pins are/are not used on the motor shield?

GND and either 5v (default) or 3.3v are required to power the logic on-board. (5v or 3v operation is selectable via

jumper)

The shield uses the SDA and SCL i2c pins to control DC and stepper motors. On the Arduino UNO these are also

known as A4 and A5. On the Mega these are also known as Digital 20 and 21. On the Leonardo these are also

known as digital 2 and 3. Do not use those pins on those Arduinos with this shield with anything other than an i2c

sensor/driver.

Since the shield uses I2C to communicate, you can connect any other i2c sensor or driver to the SDA/SCL pins as

long as they do not use address 0x60 (the default address of the shield) or 0x70 (the 'all call' address that this chip

uses for group-control)

If you want to use the servo connections, they are on pins #9 and #10. If you do not use the connector then those

pins are simply not used.

You can use any other pins for any other use

How can I connect to the unused pins?

All pins are broken out into 0.1" spaced header along the edges of the shield

My Arduino freaks out when the motors are running! Is the shield broken?

Motors take a lot of power, and can cause 'brownouts' that reset the Arduino. For that reason the shield is designed

for seperate (split) supplies - one for the electronics and one for the motor. Doing this will prevent brownouts.

Please read the user manual for information about appropriate power supplies.

I'm trying to build this robot and it doesn't seem to run on a 9V battery....

You cannot power motors from a 9V battery. You must use AA batteries or a lead acid battery for motors.

Can this shield control small 3V motors?

Not really, its meant for larger, 5V+ motors. It does not work for 3V motors unless you overdrive them at 5V and

then they will burn out faster

I have good solid power supplies, but the DC motors seem to 'cut out' or 'skip'.

Try soldering a ceramic or disc 0.1uF capacitor between the motor tabs (on the motor itself!) this will reduce noise

that could be feeding back into the circuit (thanks macegr!)

I'm using a 4WD robot platform and I can't get anything to work.

Many smal DC motor such as the ones used in the 4WD robot platforms from some distributors have a lot of "brush

noise". This feeds back into the Arduino circuitry and causes unstable operation. This problem can be solved by

soldering some 0.1uF ceramic noise suppression capacitors to the motor.

You will need 3 total. 1 between the motor terminals, and one from each terminal to the motor casing.

Note that pins A4 and A5 are connected to SDA and SCL for compatibility with classic Arduinos. These pins

are not available for use on other processors.