Pololu MC33926 User manual

Pololu Dual MC33926 Motor
Driver Shield User’s Guide
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.a. Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.b. Included ardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Contacting Pololu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Getting Started with an Arduino . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.a. What You Will Need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.b. Assembly for Use as an Arduino Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.c. Shield Connections: Signals, Power, and Motors . . . . . . . . . . . . . . . . . . . . . 10
3.d. Programming Your Arduino . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4. Using as a General-Purpose Motor Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.a. Assembly for Use as a General-Purpose Motor Driver . . . . . . . . . . . . . . . . . . 19
4.b. Board Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5. Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6. Customizing the Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.a. Remapping the Arduino Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.b. Accessing nD2 and nSF Pins Separately for Each Channel . . . . . . . . . . . . . . . 29
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
https://www.pololu.com/docs/0J55/all Page 1 of 30

Pololu dual MC33926 motor driver shield
for Arduino.
1. Overview
The Pololu dual MC33926 motor driver shield for
Arduino [https://www.pololu.com/product/2503] and its
corresponding Arduino library make it easy to control
two bidirectional, brushed DC motors with an Arduino
[https://www.pololu.com/product/2191] or compatible board,
such as the A-Star 32U4 Prime [https://www.pololu.com/
category/165/a-star-32u4-prime]. The board features a pair of
Freescale MC33926 motor drivers, which operate from 5
to 28 V and can deliver a continuous 3 A per channel,
and includes current sense circuitry, protection resistors,
a FET for reverse battery protection, and logic gates to
reduce the required number of I/O pins. It ships fully
populated with its SMD components, including the two
MC33926 ICs, as shown in the picture to the right;
stackable Arduino headers and terminal blocks for
connecting motors and motor power are included but are
not soldered in.
This versatile motor driver is intended for a wide range of users, from beginners who just want a
plug-and-play motor control solution for their Arduinos (and are okay with a little soldering) to more
advanced users who want a dual MC33926 carrier [https://www.pololu.com/product/1213] that requires
fewer I/O pins to control. The Arduino pin mappings can all be customized if the defaults are not
convenient, and the simplified MC33926 control lines are broken out along the left side of the board,
providing a convenient interface point for other microcontroller boards.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
1. Overview Page 2 of 30

Pololu dual MC33926 motor
driver shield, assembled and
connected to an Arduino
Leonardo.
Pololu dual MC33926 motor
driver shield for Arduino, bottom
view with board dimensions.
1.a. Features
• Wide operating voltage range: 5 – 28 V 1
• Output current: 3 A continuous (5 A peak 2) per motor
• Inputs compatible with both 5 V and 3.3 V systems
• PWM operation up to 20 k z, which is ultrasonic and
allows for quieter motor operation
• Current sense voltage output proportional to motor
current (approx. 525 mV/A)
• Motor indicator LEDs show what the outputs are doing
even when no motor is connected
• Can be used with an Arduino or Arduino clone (through
shield headers) or other microcontroller boards (through
0.1″ header along the left side)
• When used as a shield, the motor power supply can
optionally be used to power the Arduino base as well
• Arduino pin mappings can be customized if the default
mappings are not convenient
•Arduino library [http://github.com/pololu/dual-mc33926-motor-
shield] makes it easy to get started using this board as a
motor driver shield
• Reverse-voltage protection on motor supply 3
• Robust drivers:
◦ Transient operation (< 500 ms) up to 40 V
◦ Over-current limiting via internal PWM
◦ Over-temperature shutdown and hysteresis
◦ Under-voltage shutdown
◦ Output short-to-ground and short-to-Vcc protection
1The board supports transient (< 500 ms) operation up to 40V. Operation from 5-8 V reduces maximum
continuous output current (driver performance is derated in this range).
2Internal peak-current limiting gracefully reduces the output power at load currents above 6.5 A ± 1.5 A. See
the MC33926 datasheet [https://www.pololu.com/file/download/MC33926.pdf?file_id=0J233] (1MB pdf) for more
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
1. Overview Page 3 of 30

Pololu dual MC33926 motor driver shield for
Arduino with included hardware.
information.
3There is no reverse-voltage protection on the logic supply.
1.b. Included Hardware
This motor driver board ships with all of the
surface-mount parts populated. owever,
soldering is required for assembly of the
included through-hole parts. The following
through-hole parts are included:
• one extended/stackable 1×10 female
header (for Arduino shields)
• two extended/stackable 1×8 female
headers (for Arduino shields)
• two extended/stackable 1×6 female
headers (for Arduino shields)
• three 2-pin, 5 mm terminal blocks
[https://www.pololu.com/product/2440] (for
board power and motor outputs)
• 25-pin 0.1″ straight breakaway male header [https://www.pololu.com/product/965]
A0.1″ shorting block [https://www.pololu.com/product/968] (for optionally supplying shield power to
Arduino) is also included.
You can solder the terminal blocks to the six large through-holes to make your motor and motor power
connections, or you can break off a 12×1 section of the 0.1″ header strip and solder it into the smaller
through-holes that border these larger holes. Note, however, that each header pin pair is only rated for
a combined 6 A, so for higher-power applications, the terminal blocks should be used or thick wires
should be soldered directly to the board.
When not using this board as an Arduino shield, you can solder the 0.1″ headers to the logic
connections along the left side of the board to enable use with custom cables [https://www.pololu.com/
category/70/crimp-connector-housings] or solderless breadboards [https://www.pololu.com/category/28/
solderless-breadboards], or you can solder wires directly to the board for more compact installations.
Note that motor and motor power connections should not be made through a breadboard.
The mounting hole is intended for use with #4 screws [https://www.pololu.com/category/101/nuts-and-
screws] (not included).
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
1. Overview Page 4 of 30

An Arduino [https://www.pololu.com/product/2191] is not included.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
1. Overview Page 5 of 30

Pololu dual MC33926 motor
driver shield, assembled and
connected to an Arduino Uno R3.
2. Contacting Pololu
We would be delighted to hear from you about any of your
projects and about your experience with the dual MC33926
motor driver shield for Arduino [https://www.pololu.com/product/
2503]. If you need technical support or have any feedback you
would like to share, you can contact us [https://www.pololu.com/
contact] directly or post on our forum [http://forum.pololu.com/
viewforum.php?f=15]. Tell us what we did well, what we could
improve, what you would like to see in the future, or anything else
you would like to say!
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
2. Contacting Pololu Page 6 of 30

3. Getting Started with an Arduino
As with virtually all other Arduino shields, connections between the Arduino and the motor driver are
made via extended stackable headers that must be soldered to the through-holes along the top and
bottom edges of the shield. This section explains how to use this motor driver as an Arduino shield to
quickly and easily add control of up to two DC motors to your Arduino project. For information on how
to use this board as a general-purpose motor driver controlled by something other than an Arduino,
see Section 4.
3.a. What You Will eed
The following tools and components are required for getting started using this motor driver as an
Arduino shield:
•An Arduino or compatible control board. Using this product as an Arduino shield (rather
than a general-purpose motor driver board) requires an Arduino [https://www.pololu.com/
product/2191]. This shield should work with all Arduinos and Arduino clones that behave like a
standard Arduino. You will also need a USB cable for connecting your Arduino to a computer.
We have specifically tested this shield (using our Arduino library) with:
◦A-Star 32U4 Prime [https://www.pololu.com/category/165/a-star-32u4-prime]
◦Arduino Uno [https://www.pololu.com/product/2191] (both original and R3)
◦Arduino Leonardo [https://www.pololu.com/product/2192]
◦Arduino Due [https://www.pololu.com/product/2193]*
◦Arduino Mega 2560 [https://www.pololu.com/product/1699]
◦ Arduino Duemilanove (both with ATmega168 and ATmega328P)
•A soldering iron and solder. The through-hole parts included with the shield must be
soldered in before you can plug the shield into an Arduino or before you can connect power
and motors. An inexpensive soldering iron [https://www.pololu.com/product/156] will work, but
you might consider investing in a higher-performance, adjustable soldering iron if you will be
doing a lot of work with electronics.
•A power supply. You will need a power supply, such as a battery pack, capable of delivering
the current your motors will draw. See the Power Connections and Considerations portion of
Section 3.c for more information on selecting an appropriate power supply.
•One or two brushed DC motors. This shield is a dual motor driver, so it can independently
control two bidirectional brushed DC motors. See the Motor Connections and Considerations
portion of Section 3.c for more information on selecting appropriate motors.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 7 of 30

*ote for Due users: The voltage on the current sense pins will exceed the Due’s 3.3 V
limit when the current draw exceeds ~6 A. The CS circuit has a 1 kΩ resistor in series with
the output, which offers some protection to the analog input, and the driver has over-current
protection that kicks in between 5 A and 8 A, so the risk to the Due is low, but if you really
want to be safe, you can use a 3.3 V zener diode to clamp the current sense output voltage
to a maximum of ~3.3 V. Alternatively, you can disconnect the shield’s current sense pins
from the Due (and optionally reconnect them through a voltage divider); see Section 6.a for
more information.
3.b. Assembly for Use as an Arduino Shield
1. Stackable Arduino headers: Before you can use this board as an Arduino shield, you need
to solder four of the five included Arduino header strips to the set of holes highlighted in red
in the picture above. The headers should be oriented so that the female sockets rest on the
top side of the shield and face up while the male pins protrude down through the board,
and the solder connections should be made on the underside of the shield. Newer Arduinos,
including the Uno R3 and the Leonardo, use one 10×1 header, two 8×1 headers, and one 6×1
header, as shown in the left picture below. If you happen to have an older Arduino that lacks
the new pins introduced when the Uno R3 was released, you should assemble the shield
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 8 of 30

with two 8×1 headers and two 6×1 headers; the right picture below shows an example of the
shield assembled in this way (note: the shield can still be used with newer Arduinos when
assembled in this way, and it is actually plugged into an Uno R3 in the picture). In short, the
two pairs of pins highlighted above in darker red should not be populated if you are using this
board with an older Arduino that does not support these additional pins. Please make sure
you solder the appropriate headers for your particular Arduino!
2. Motor and power connections: The six large holes/twelve small holes on the right side
of the board, highlighted in yellow in the above diagram, are the motor outputs and power
inputs. You can optionally solder the included 5mm-pitch terminal blocks to the six large holes
to enable temporary motor and motor power connections, or you can break off a 12×1 section
of the included 0.1″ header strip and solder it into the smaller through-holes that border the
six large motor and motor power pads. Note, however, that each header pin pair is only
rated for a combined 6 A, so for higher-power applications, the terminal blocks should be
used or thick wires with high-current connectors [https://www.pololu.com/product/925] should
be soldered directly to the board. The smaller holes are intended only for 0.1″ header pins,
not for the terminal blocks!
3. Arduino power jumper: If you want the option of powering your Arduino and motor shield
from the same source, you can solder a 2×1 piece of the included 0.1″ male header strip to
two the pins highlighted in orange in the above picture. Shorting across these pins with the
included shorting block will connect the shield power to the Arduino’s VIN pin. You should not
use this to power the shield from the Arduino as this connection is not designed to handle
high currents, and you must never supply power to the Arduino’s VIN pin or power jack while
this shorting block is in place, because it will create a short between the shield power supply
and the Arduino power supply and will likely permanently damage something.
4. Arduino pin breakout points: The shield provides a secondary access point for each
Arduino pin, divided into two rows of pins spaced on a 0.1″ grid (unlike the standard
Arduino pins, which have a half-pin offset introduced by the gap in the top row). You can
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 9 of 30

optionally solder 0.1″ female headers (not included) to these pins. Note that the SCL and SDA
breakouts are top-layer pads only, not through-holes, due to the close proximity of Arduino
pins below.
The other through-holes on the shield are used for more advanced things like customizing the Arduino
pin mappings or using the board with other microcontrollers. They are not necessary for getting started
using this shield with an Arduino, and they are discussed in more detail later in this guide.
3.c. Shield Connections: Signals, Power, and Motors
Using the dual MC33926 motor driver shield with an Arduino (shield and Arduino powered
separately).
All of the necessary logic connections between the Arduino and the motor driver shield, including
VDD, are made automatically when the shield is plugged into the Arduino. owever, the shield’s motor
power must be supplied directly to the shield itself via its large, high-current VIN and GND pads.
The motor channels, located on either side of these power pins, can each be used to independently
control a bidirectional brushed DC motor. Each motor channel is comprised of a pair of pins—MxA and
MxB—that connect to the two terminals of a DC motor and can deliver a continuous 3 A (5 A peak).
The picture above shows the typical connections involved in using this board as an Arduino shield. In
the depicted configuration, the Arduino is powered separately from the shield, such as through its USB
connector or power jack.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 10 of 30

Default Arduino Pin Mappings
The following table shows how the shield connects your Arduino’s pins to the motor drivers’ pins:
Arduino
Pin
Shield Pin
ame Basic Function
Digital 4 D2 (or nD2)
Tri-state disables both outputs of both motor channels when
LOW;
toggling resets latched driver fault condition
Digital 7 M1DIR Motor 1 direction input
Digital 8 M2DIR Motor 2 direction input
Digital 9 M1PWM Motor 1 speed input
Digital 10 M2PWM Motor 2 speed input
Digital 12 SF (or nSF) Status flag indicator (LOW indicates fault)
Analog 0 M1FB Motor 1 current sense output (approx. 525 mV/A)
Analog 1 M2FB Motor 2 current sense output (approx. 525 mV/A)
See Section 4.b for more detailed descriptions of the shield pins and a motor control
truth table. See Section 5 for a schematic diagram of the shield. See Section 6.a for
instructions on how to customize your board’s Arduino pin mappings if the above defaults
are not convenient.
Power Connections
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 11 of 30

Dual MC33926 motor driver shield power buses when connected to an
Arduino.
In the shield’s default state, the motor driver shield and Arduino are powered separately. When used
this way, the Arduino must be powered via USB, its power jack, or its VIN pin, and the shield must be
supplied with 5 to 28 V through the large VI and G D pads on the right side of the board. Attempting
to power the shield through other means, such as from the Arduino or through the small VOUT pin, can
permanently damage both the Arduino and the shield (only the large power traces on the right side of
the shield are designed to handle the high currents involved in powering motors). A high-side reverse-
voltage protection MOSFET prevents the shield from being damaged if motor power is inadvertently
connected backwards. Logic power, VDD, is automatically supplied by the Arduino.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 12 of 30

Using the dual MC33926 motor driver shield with an Arduino (Arduino powered by shield).
It is also possible to power your Arduino directly from the motor shield, as shown in the diagram above,
which eliminates the need for a separate Arduino power supply. When the ARDVI =VOUT shorting
block is in place, the shield’s reverse-protected input power, VOUT, is connected to the Arduino’s
VIN pin. (When power is connected properly, VOUT is essentially the same as the shield’s VIN.) The
Arduino’s power jack must remain disconnected at all times in this configuration.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 13 of 30

Warning: When powering the Arduino from the motor shield, you must never connect a
different power supply to the Arduino’s VIN pin or plug a power supply into the Arduino’s
power jack, as doing so will create a short between the shield’s power supply and the
Arduino’s power supply that could permanently damage both the Arduino and the motor
shield. In this case, it is also important that your shield power supply is an acceptable voltage
for your Arduino, so the full shield operating voltage range of 5 – 28 V probably will not be
available. For example, the recommended operating voltage of the Arduino Uno is 7 – 12 V.
Note that the shorting block just routes the motor power to the Arduino VIN pin, so plugging
in USB with this shorting block in place is just like plugging in USB with the Arduino powered
from its power jack. On standard Arduinos we recommend against plugging a powered
Arduino into USB (see this forum post [https://forum.pololu.com/t/pololu-arduino-hardware-bug/
2461/7] for more information), but on some Arduino-compatible boards such as the A-Stars
[https://www.pololu.com/category/165/a-star-32u4-prime], this is completely safe.
Power Considerations
The shield operates from 5 to 28 V, but it can tolerate transient voltages (shorter than 500 ms in
duration) of up to 40 V, which means it is generally safe to power this board with a 24 V battery.
At voltages between 5 and 8 V, the shield performance is derated, and the maximum achievable
continuous output current will be decreased (according to the MC33926 datasheet, -bridge MOSFET
on-resistances might increase by 50% in this “quasi-functional” performance region). The shield
operating voltage range is much wider than the typical Arduino operating voltage range, so if you are
using the shield to power your Arduino, please ensure that your voltage source is within acceptable
limits for your Arduino as well as the shield.
It is important that you use a power source that is capable of delivering the current your motors will
require. For example, alkaline cells are typically poor choices for high-current applications, and you
should almost never use a 9V battery (the rectangular type with both terminals on the same side) as
your motor power supply. We recommend iMH batteries [https://www.pololu.com/category/54/batteries],
lithium-based rechargeable batteries (if you have a good charger and adequately understand the
dangers of using them improperly), or a power adapter with an appropriate power rating. The current
draw is ultimately a function of your motors, your operating voltage, and your motor load, but the driver
is capable of delivering a continuous 6 A (3 A per channel), and it can deliver in excess of 10 A before
the internal current limiting is activated.
Shield Power Dissipation
Each MC33926 motor driver IC has a maximum continuous current rating of 5 A. owever, the actual
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 14 of 30

current it can deliver depends on how well you can keep it cool. The shield’s printed circuit board is
designed to draw heat out of the motor driver chips, but performance can be improved by adding heat
sinks.
Unlike other -Bridges, the MC33926 has a feature that allows it to gracefully reduce current as the
current exceeds 5 A or as the chip temperature approaches its limit. This means that if you push the
chip close to its limit, you will see less power to the motor, but it might allow you to avoid a complete
shutdown.
We tested the shield at room temperature with no forced air flow or heat sinks. In our tests, the shield
was able to deliver 5 A to both channels simultaneously for 10 s before the thermal protection started
reducing the current. The shield delivered 4 A on both channels for 37 s, and at 3 A it was able to
operate continuously for over 10 minutes without triggering current limiting or thermal protection.
Our tests were conducted at 100% duty cycle; PWMing the motor will introduce additional heating
proportional to the frequency.
This product can get hot enough to burn you long before the chip overheats. Take care
when handling this product and other components connected to it.
Motor Considerations
If your motor has a stall current over the driver’s continuous current rating of 3 A per channel, we
recommend you take extra steps to make sure that your motor will not be exposed to loads that will
cause it to exceed 3 A for prolonged periods of time (or you take extra steps to keep the motor drivers
cool, such as increasing air flow or adding heat sinks). Exceeding 3 A for long durations should not
damage the shield, but it will eventually activate the driver’s thermal protection, which might result in
inadequate performance for your application.
It is not unusual for the stall current of a motor to be an order of magnitude (10×)
higher than its free-run current. If you do not know your motor’s stall current, you can
approximate it by measuring the current it draws while held stalled at a lower voltage
(such as when powered from a single battery cell) and then scaling that value linearly
with voltage. For example, the stall current of a motor at 6 V is six times the stall current
of that motor at 1 V. Another, less accurate method is to use a multimeter to measure
the resistance between the motor terminals and then use Ohm’s law to compute the stall
current Iat voltage V:I=V/R. This last method generally is not as reliable because it
can be difficult to measure such small resistances accurately.
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 15 of 30

Motor with one 0.1 uF
capacitor soldered across its
terminals.
Motor with two 0.1 uF
capacitors soldered from its
terminals to its case.
Occasionally, electrical noise from a motor can interfere with the rest of the system. This can depend
on a number of factors, including the power supply, system wiring, and the quality of the motor. If you
notice parts of your system behaving strangely when the motor is active, first double-check that your
power supply is adequate, then consider taking the following steps to decrease the impact of motor-
induced electrical noise on the rest of your system:
1. Solder a 0.1 µF ceramic capacitor [https://www.pololu.com/
product/1166] across the terminals of your motors, or solder
one capacitor from each terminal to the motor case (see the
pictures to the right). For the greatest noise suppression,
you can use three capacitors per motor (one across the
terminals and one from each terminal to the case).
2. Make your motor leads as thick and as short as possible,
and twist them around each other. It is also beneficial to do
this with your power supply leads.
3. Route your motor and power leads away from your logic
connections if possible.
4. Place decoupling capacitors (also known as “bypass
capacitors”) across power and ground near any electronics
you want to isolate from noise. These can typically range
from 10 uF to a few hundred uF.
3.d. Programming Your Arduino
Our Arduino library for the dual MC33926 motor driver shield makes it easy to get started writing your
Arduino sketches. A link to download the library, installation instructions, and the library command
reference can be found on the library’s github page [http://github.com/pololu/dual-mc33926-motor-shield].
Once installed, we recommend you try out the example sketch by selecting
File > Examples > DualMC33926MotorShield > Demo
from the Arduino IDE, or by copying the following code into a new sketch:
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 16 of 30

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#include "DualMC33926MotorShield.h"
DualMC33926MotorShield md;
void stopIfFault()
{
if (md.getFault())
{
Serial.println("fault");
while(1);
}
}
void setup()
{
Serial.begin(115200);
Serial.println("Dual MC33926 Motor Shield");
md.init();
}
void loop()
{
for (int i = 0; i <= 400; i++)
{
md.setM1Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
{
Serial.print("M1 current: ");
Serial.println(md.getM1CurrentMilliamps());
}
delay(2);
}
for (int i = 400; i >= -400; i--)
{
md.setM1Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
{
Serial.print("M1 current: ");
Serial.println(md.getM1CurrentMilliamps());
}
delay(2);
}
for (int i = -400; i <= 0; i++)
{
md.setM1Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
{
Serial.print("M1 current: ");
Serial.println(md.getM1CurrentMilliamps());
}
delay(2);
}
for (int i = 0; i <= 400; i++)
{
md.setM2Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
?
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 17 of 30

This example ramps motor 1 speed from zero to max speed forward, to max speed reverse, and back
to zero again over a period of about 3 s, while checking for motor faults and periodically printing the
motor current to the serial monitor. It then performs the same process on motor 2 before repeating all
over again.
ote: Even if you do not have any motors yet, you can still try out this sketch and use
the motor indicator LEDs for feedback that the shield is working properly.
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{
Serial.print("M2 current: ");
Serial.println(md.getM2CurrentMilliamps());
}
delay(2);
}
for (int i = 400; i >= -400; i--)
{
md.setM2Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
{
Serial.print("M2 current: ");
Serial.println(md.getM2CurrentMilliamps());
}
delay(2);
}
for (int i = -400; i <= 0; i++)
{
md.setM2Speed(i);
stopIfFault();
if (abs(i)%200 == 100)
{
Serial.print("M2 current: ");
Serial.println(md.getM2CurrentMilliamps());
}
delay(2);
}
}
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
3. Getting Started with an Arduino Page 18 of 30

4. Using as a General-Purpose Motor Driver
MC33926 motor driver control lines and output signals are available via the set of pins along the left
side of the board, which means this shield can be used as a general-purpose motor driver controlled by
devices other than Arduinos. This section explains how to use the dual MC33926 motor driver shield
this way and provides some basic information about the motor driver pins to help get you started.
owever, we strongly encourage you to consult the MC33926 datasheet [https://www.pololu.com/file/
download/MC33926.pdf?file_id=0J233] (1MB pdf) for detailed pin descriptions, truth tables, and electrical
characteristics. This shield is essentially a breakout board for two MC33926 motor driver ICs with
additional logic circuitry to simplify the motor control, so the datasheet is your best resource for
answering questions not covered by this user’s guide.
4.a. Assembly for Use as a General-Purpose Motor Driver
1. Logic connections: The 11 small holes along the left side of the board, highlighted in red
in the above diagram, are used to interface with the motor drivers. You can optionally solder
a 11×1 piece of the included 0.1″ male header strip to these pins. Soldering the pins so
they protrude down allows the logic side of the motor driver to be plugged into a standard
solderless breadboard [https://www.pololu.com/category/28/solderless-breadboards] or perfboard.
You can also solder 0.1″ female headers [https://www.pololu.com/category/50/0.1-2.54-mm-female-
headers] or custom connectors to these pins.
2. Motor and power connections: The six large holes/twelve small holes on the right side
of the board, highlighted in yellow in the above diagram, are the motor outputs and power
inputs. You can optionally solder the included 5mm-pitch terminal blocks to the board to
enable temporary motor and motor power connections, or you can break off an 12×1 section
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
4. Using as a General-Purpose Motor Driver Page 19 of 30

of the included 0.1″ header strip and solder it into the smaller through-holes that border the
six large motor and motor power pads. Note, however, that each header pin pair is only
rated for a combined 6 A, so for higher-power applications, the terminal blocks should be
used or thick wires with high-current connectors [https://www.pololu.com/product/925] should
be soldered directly to the board.
3. Enable Jumper: You can optionally solder a wire or a 2×1 piece of the included 0.1″ male
header strip to the two pins highlighted in orange in the above diagram to create a board
enable jumper. The left pin is D2, and the right pin is VDD. D2 is internally pulled low, which
tri-state disables the motor driver outputs and allows any connected motor to coast. In order
to enable the board, this pin must be driven high, either through a connection to an I/O line
or by connecting it to the neighboring VDD pin.
With the exception of the pins labeled “D2 1=2” and “SF 1=2”, all of the through-holes not highlighted
in the above diagram are only relevant when using this driver as an Arduino shield. The “D2 1=2” and
“SF 1=2” pins are explained in the “Pinout” portion of Section 4.b, but they will not be needed in typical
applications and can generally be ignored.
4.b. Board Connections
Using the dual MC33926 motor driver shield with a microcontroller (gray connections are
optional).
The above diagram shows the minimum connections typically required to interface this motor driver
with a microcontroller. Note that D2 is internally pulled low, which disables the motor outputs; it must
either be connected to an I/O line (for dynamic control) or soldered to the neighboring VDD pin to
Pololu Dual MC33926 Motor Driver Shield User’s Guide © 2001–2017 Pololu Corporation
4. Using as a General-Purpose Motor Driver Page 20 of 30