Advice for Adding Bluetooth to Zumo 32u4


I am interested in adding Bluetooth connectivity to my Zumo 32u4. With Bluetooth, it would be fun to build a toy mobile app that supports pressing the A, B, and C buttons remotely.

Does anyone have advice on how to do this?

One forum post ( suggests that adding an HC-06 chip might be the way to go, although it seems like some people had trouble with that. Also, I assume that involves soldering, which I would prefer to avoid, although it might be unavoidable.

Do you think using a standard USB Bluetooth adapter would work (assuming I connected it to the Zumo via an intermediate USB A to USB B adapter)?


David Silver

Hello, David.

The ATmega32U4 microcontroller on the Zumo 32U4 does not have the functionality to serve as a USB host that would be necessary for USB peripherals like a USB to Bluetooth adapter to work.

The HC-06 is a bluetooth to TTL serial module. The “Expansion areas” and “Pin Assignements” sections of the Zumo 32U4 Robot User’s Guide show the location and describe the functionality of the expansion pins, including the TTL serial pins. This Adafruit tutorial for performing serial communication with an Arduino might also help you determine how you might write a program to communicate back and forth.



I managed to add bluetooth to my Zumo 32u4 using a HC-05 bluetooth chip.

First, you need to take off the LCD Screen to get to the TX and RX Pin. It is PD2 and PD3 as shown on the expansion areas.

Then you need to add a voltage divider to your bluetooth chip and connect it to TX and RX as well as 5V and GND.

The last step, and the most crucial one, is to rewrite your code as if you would be working with a Leonardo. When your code uses serial connection to send commands, you need to change the Serial class to Serial1 (note the extra 1 at the end).

It took me a lot of time to figure that one out, but once I had changed the Serial to Serial1, everything worked as expected. I am now using an App made via the MIT AppInventor and an Android Tablet to control the Zumo 32u4 + HC-05 via Bluetooth.

Hope that helps,


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