Arduino motor shield, Rev3 A000079

The Arduino Motor Shield is based on the L298 (datasheet),
which is a dual full-bridge driver designed to drive inductive
loads such as relays, solenoids, DC and stepping motors. It lets
you drive two DC motors with your Arduino board, controlling
the speed and direction of each one independently.
You can also measure the motor current absorption of each motor,
among other features. The shield is TinkerKit compatible, which
means you can quickly create projects by plugging TinkerKit
modules to the board.
 
Operating Voltage 5V to 12V
Motor controller L298P, Drives 2 DC motors or 1 stepper motor
Max current 2A per channel or 4A max (with external power supply)
Current sensing 1.65V/A
Free running stop and brake function
 
 
Power
The Arduino Motor Shield must be powered only
by an external powe r supply. Because the L298 IC mounted on
the shield has two separate power connections, one for the logic and
one for the motor supply driver. The required motor current often
exceeds the maximum USB current rating.
External (non-USB) power can come either fro an AC-to-DC adapter
(wall-wart) or battery.
The adapter can be connected by plugging a 2.1mm center-positive
plug into the Arduino's board power jack on which the motor shield is
mounted or by connecting the wires that lead the power supply to the
Vin and GND screw terminals, taking care to respect the polarities.
To avoid possible damage to the Arduino board on which the shield
is mounted, we reccomend using an external power supply that provides a
voltage between 7 and 12V. If your motor require more than 9V we
recommend that you separate the power lines of the shield
and the Arduino board on which the shield is mounted.
This is possible by cutting the "Vin Connect" jumper placed on the back
side of the shield. The absolute limit for the Vin at the
screw terminals is 18V. The power pins are as follows: Vin
on the screw terminal block, is the input voltage to the motor connected
to the shield. An external power supply connected to this pin also provide
power to the Arduino board on which is mounted. By cutting the
"Vin Connect" jumper you make this a dedicated power line for the motor.
 
GND, Ground on the screw terminal block.
The shield can supply 2 amperes per channel, for a total of 4 amperes
maximum.
 
Input and Output
This shield has two separate channels, called A and B, that each use 4
of the Arduino pins to drive or sense the motor. In total there are 8 pins
in use on this shield. You can use each channel separately to drive two
DC motors or combine them to drive one unipolar stepper motor.
The shield's pins, divided by channel are shown in the table below:
Function pins per Ch.
A pins per Ch.
B Direction D12 D13
PWM D3 D11
Brake D9 D8
Current Sensing A0 A1

If you don't need the Brake and the Current Se nsing and you also need
more pins for your application you can disable this features by cutting
the respective jumpers on the back side of the shield.
 
The additional sockets on the shield are described as follow:
Screw terminal to connect the motors and their power supply.
2 TinkerKit connectors for two Analog Inputs (in white), connected
to A2 and A3.
2 TinkerKit connectors for two Aanlog Outputs (in orange in the
middle), connected to PWM outputs on pins D5 and D6.
2 TinkerKit connectors for the TWI interface (in white with 4 pins),
one for input and the other one for output.
 
Motors connections
Brushed DC motor
. You can drive two Brushed DC motors by connecting the two wires of
each one in the (+) and (-) screw terminals fo r each channel A and B.
In this way you can control its direction by setting HIGH or LOW the
DIR A and DIR B pins, you can control the speed by varying the
PWM A and PWM B duty cycle values.
The Brake A and Brake B pins, if set HIGH, will effectively brake
the DC motors rather than let them slow down by cutting the power.
You can measure the current going through the DC motor by reading
The SNS0 and SNS1 pins.
On each channel will be a voltage proportional to the measured current,
which can be read as a normal analog input, through the function
analogRead() on the analog input A0 and A1.
For your convenience it is calibrated to be 3.3V when the channel is
delivering its maximum po ssible current, that is 2A.
 
Physical Characteristics
The maximum length and width of the Motor Shie ld PCB are 2.7 and
2.1 inches respectively.
Four screw holes allow the board to be attached to a surface or case.
 
Note that the distance between digital pins 7 and 8 is 160 mil (0.16"),
not an even multiple of the 100 mil spacing of the other pins.