1.2. What you will need

These additional items are needed for using the Zumo 32U4 robot:

Micro Metal Gearmotor with Extended Motor Shaft.

• four AA batteries—the robot works with both alkaline and NiMH batteries, though we recommend using rechargeable AA NiMH cells
• USB A to Micro-B cable to connect the robot to your computer for programming and debugging
• small 2 mm slotted screwdriver for adjusting the LCD contrast (original LCD version only)

In addition, the kit version of the robot requires:

• two micro metal gearmotors with extended motor shafts (see below)

Kit motor selection

The kit version of the Zumo 32U4 robot requires the addition of two micro metal gearmotors with extended motor shafts, one for each tread.

The ideal motors for your robot depend on your desired torque, speed, and current draw. We generally recommend using HP versions of our micro metal gearmotors since the tracks require a decent amount of torque to move effectively; higher gear ratios of the non-HP motors might work if you want lower current draw, but they will be slower and offer less control.

If you are unsure which motors to choose, we recommend getting two of the 75:1 Micro Metal Gearmotor HP with Extended Motor Shaft, which offer a good balance of performance characteristics, and most of our example code was developed and tested with these motors. 50:1 HP and 100:1 HP motors also generally work well. These three motor types are the ones we offer in assembled Zumo 32U4 robots.

The following table summarizes the key specifications of the recommended 50:1 HP, 75:1 HP, and 100:1 HP motors. The first four columns are specifications of the motors themselves, while the last column is the measured top speed of a Zumo chassis loaded to a weight of 500 g and driven with these motors. Note that the specifications are for 6V operation, which is approximately the voltage you would get with four fresh alkaline batteries; four NiMH AA cells will typically provide less than 5V.

Micro Metal Gearmotor	Free-Run Speed @ 6V	Stall Torque @ 6V	Stall Current @ 6V	Top Zumo Speed @ 6V and 500g
50:1 HP	625 RPM	15 oz·in	1600 mA	40 in/s	(100 cm/s)
75:1 HP	400 RPM	22 oz·in	1600 mA	25 in/s	(65 cm/s)
100:1 HP	320 RPM	30 oz·in	1600 mA	20 in/s	(50 cm/s)

For more options, you can see our other micro metal gearmotors with extended motor shafts. Be sure to pick a motor that has an extended shaft, or else you will not be able to use the encoders on the Zumo 32U4.

Kit assembly tools

These additional items are needed for assembling the Zumo 32U4 robot kit:

• soldering iron and solder (we recommend one with adjustable temperature control)
• wire cutter
• small #1 Phillips screwdriver
• 3 mm Allen wrench (hex key)
• long-nose pliers (for bending the IR LED leads and Zumo 32U4 blade mounting tabs)
• tape or small clamps (for holding parts together when soldering)

Additional optional components

You might also consider getting these for your Zumo 32U4 robot:

• Sensors, such as optical or sonar range finders (the Zumo 32U4 already has built-in IR proximity sensors, but additional sensors can be incorporated for increased range or detection area)
• Connectors and jumper wires, for connecting additional sensors and components
• Battery charger, if you are using rechargeable batteries; since the Zumo just uses ordinary AA batteries, we recommend basic AA chargers (into which you stick the individual cells) available at most general electronics stores, though we carry a much fancier iMAX-B6AC V2 balance charger/discharger that can be also used for this