iRobot DJ Create User manual

DJ Create
So you want to impress your friends with a roaming,
robotic DJ at your next party, but that speaker that you
glued on top of your Create®2 keeps getting knocked
o. Follow along here and see how you can build your
own DJ Create.
Get ready to rock with a roaming, robotic DJ! We will
show you how put two speakers and a Bluetooth module
into your Create 2 bin for less than $15 in parts.
Overview
Preparing your electronics
1) Remove all of your electronics from their packaging
and lay them out on your work surface.
2) Choose which speaker will be the left and which will
be the right and label them accordingly.
Wiring the audio amplier board
1) Connect each speaker to the corresponding screw-
down terminals on the amplier board. Be careful to
observe the correct speaker polarities, but getting
them wrong won’t blow anything up.
2) Connect the battery holder to the corresponding
power connections on the amplier board. Be careful
to observe the correct polarities—positive voltage to
the “+” terminal (usually a red wire), negative to the
“-“ terminal (usually a black wire). Getting this wrong
will likely damage the amplier.
(See diagram on the next page.)
STEM Skills:
• Mechanical
• Electrical
Experience Level:
Advanced
Supplies:
• iRobot Create 2
• Screwdrivers (#1 Phillips
& Small Flathead)
• Hot Glue Gun
• Soldering Equipment
• Wire Cutters/Strippers
• Heat Shrink Tubing or
Electrical Tape
• Flexible Wire
• Rotary Cutting Tool
• Hook and Loop Fastener
• Battery Holder with
Cover and Switch for
4 AA Batteries (ex.
SparkFun PRT-12083)
• 2 Thin .5W Speaker (ex.
SparkFun COM-15350)
• Stereo Bluetooth
Amplier Board (ex.
SparkFun DEV-17224)
Additional Resources
• Getting Started
with Create 2
Create | Advanced

Testing your electronics
1) Install 4x AA batteries into the battery holder and slide the power switch to ON.
2) A blue LED on the Bluetooth module should start ashing and the speakers should beep
to indicate pairing mode.
3) Connect your Bluetooth music player by going to your settings screen and selecting the
new Bluetooth device “XY-P40W.”
4) Select a song and make sure your speakers are playing properly. The indicator should
stay on while connected and blink slowly while playing audio.
Installing the electronics in your vacuum bin
1) Remove the vacuum bin from your robot and ip it upside down.
2) Use your #1 Phillips screwdriver to remove the six screws (circled in the image below)
holding the bin together and set them aside.
SPK2+
SPK2–
SPK1–
SPK1+
POWER–
POWER+
POWER

3) Separate the upper and lower bin housings.
4) Remove the screws holding the vacuum fan in place and slide it out of the bin.
5) Use a athead screwdriver to release the four snap clips holding the top cover on.
Remove the cover and pull the vacuum impeller o of the motor shaft. This can
be achieved by twisting and pulling or by prying from underneath with a athead
screwdriver.
6) Remove the two Phillips screws holding the motor in place. Remove the motor from the
plastic housing, cut the red and black wires about an inch from the back of the motor,
and put it aside for use in a future project.

7) Use a rotary cutting tool to trim the vacuum housing pieces in half to create space in the
bin for the speakers.
8) Reinstall the smaller plastic piece and the latch spring into the top bin housing and screw
it into place. Make sure you have the plastic latch seated properly too.
9) Turn on your hot glue gun and apply glue to the two pivot arms on the latch at the back
edge of the bin.
10) Now use your rotary tool to remove the plastic lip at the rear of the bin bottom as shown
in the image below.
11) Reassemble the bin, being sure to capture the rear grill in place properly. Reinstall the six
screws to clamp the bin back together.

12) Grab your hot glue gun again and position the speakers up against the plastic grill at the
rear of the bin while you wait for it to heat up. Be sure to position the speakers on the
appropriate side of the bin.
13) When ready, tack both speakers in place with dots of hot glue. Then, run a small bead of
hot glue around the perimeter of the speakers.
14) While the glue is still hot, clean up any excess glue that may have leaked through the
plastic grill to the outside of the bin.
15) Position the electronics in the bin and xture them in place using Velcro or a similar
method. This will prevent the components from rattling around in the bin and possibly
shorting against each other.
Install your new DJ Create 2 bin into the robot, turn on the power, and enjoy the music!
Optional Upgrade #1: Upgrade your battery pack
Replace your 4xAA battery holder with a portable USB power bank. Then, use a DIY USB A
connector shell (example: Adafruit 1387) to wire a male USB A plug to the power input of the
audio amplier board instead of the AA battery pack, and simply plug the USB connector into
the power bank. Be sure to check your polarity before starting everything!

Optional Upgrade #2:
Power your electronics using Create’s internal battery
Connect a 5V UBEC (Buck) Converter to the dust bin electrical contacts and use power from
your Create 2 internal battery to power your electronics.
Shopping List:
• UBEC DC/ DC Step-Down (Buck) Converter – 5V @ 3A Output (Ex. Adafruit 1385)
• Inductor 2.2mH 500mA
Examples:
àAbraco Corporation AIAP-03-222-K
àVishay Dale IHD3EB222L
àBourns Inc. 5900-222-RC
Instructions:
1) Instead of attaching the battery holder wires to the amplier module, cut o the
connector on the output.
2) of the UBEC, strip the insulation o the wires, and screw the UBEC output wires to the
power terminals on the amplier module.
3) Solder the red UBEC input wire to the red vacuum motor wire (the left vacuum bin
contact).
4) Solder one lead of the inductor to the black vacuum motor wire (the right vacuum bin
contact).
5) Solder the black UBEC input wire to the other lead of the inductor.
6) Use hot glue to secure the inductor somewhere in the bin so it doesn’t pull on the wires.
7) Plug the bin into the robot and command the robot to drive to apply power to the
bin contacts (either by pressing Clean to start a mission or using the Open Interface
command Motor – 138).
Now your electronics are powered by Create’s internal battery!

Why is the inductor necessary?
The motor driver was designed to drive an inductive load (motors have a lot of inductance).
The input to the UBEC is a large capacitor. If you were to connect the input directly to the
motor driver output then it eectively shorts the UBEC input capacitor to the battery voltage
when the motor driver turns on.
Since the capacitor is initially discharged, a very large current ows in quickly and causes
the motor driver to trip the current limit and turn o to protect itself. Installing the inductor
between the motor driver and the UBEC adds the inductance back into the circuit and limits
the rate of current rise so that the input capacitor can be charged without tripping the
current limit.
How do inductors work?
An inductor obeys the following formula: V = L * di/dt
V Voltage across the inductor (volts)
L Value of inductance (Henrys)
di Change in current (amps)
dt Change in time (seconds)
If a positive voltage is applied across an inductor then the current owing through it
increases over time. There is also energy stored in the inductor. If a negative voltage is
applied across the same inductor then the current owing through the inductor decreases
over time and the energy stored in the inductor is transferred to the other circuitry. Inductors
are used in power supplies to control current and store energy.
Acknowledgments
Thanks to Instructables user ASCAS for the inspiration:
https://www.instructables.com/member/ASCAS/instructables/
So What’s Next?
Start your party! Your DJ Create can roam the house, wake you up to your favorite tunes, or
just be your best buddy singing along with you. Don’t worry, there’s no camera so dance like
no one is watching! Share your project with [email protected]
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