Romi 32u4 and HC-06 bluetooth module

Unfortunately the micro-usb port on my romi 32u4 (control board) detached and I tried to solder it on again, but failed to do so. To counter this, I am trying to use a HC-06 bluetooth module connected to the RX and TX (pins 0 and 1 respectively).
I keep getting an error while uploading. (The bluetooth is connected at this point).

Error is = avrdude: butterfly_recv(): programmer is not responding.

Is it possible to upload through the HC-06 module or is there something wrong with my code?


I am sorry to hear your Romi 32U4 control board got damaged. Unfortunately, the Romi’s bootloader only supports USB, so you cannot program it through the RX and TX pins. Instead, you could program the control board using an AVR programmer like this connected to the ISP pins, which I have boxed in red in the diagram bellow.

You would correspondingly need to reconfigure the Arduino IDE to upload via an AVR ISP programmer rather than a COM port. Please let me know if you want to go this route and need help with this.

Alternatively, if you email us with your order information, we might be able to get you a discount on a replacement board.


I am trying to create a rc car with the chasis kit.

Before I continue, using this board. Is it able to communicate with another arduino or something similar. Are there any other attachments that can help with this or can I use the NRF24L01 that i was planning to.

The Romi Control Board cannot communicate wirelessly with other devices by itself, but the NRF24L01 seems like an okay option for adding that kind of functionality. Please note that the only access points to the SPI pins on the control board are through the ISP programming header, so you would need removable connections that allow you to alternate between plugging in the NRF24L01 and the AVR programmer.

By the way, a second alternative would be to use a pair of Wixels, which are general-purpose programmable modules featuring a 2.4 GHz radio and USB, for communication between the Romi and another device.

A third alternative would be for you to use an actual RC transmitter and receiver to control your Romi, and we have an example sketch for that in our Romi 32U4 Arduino library.


hello Patrick!
can i be able to use bluetooth module on Romi32U4 for serial communication with a mobile app to send commands to the robot to move stop and all?

HC06 Module with romi32U4 !
well if it can be connected and be used for communication, then what are the header files needed?


You can use a Bluetooth module like that for wireless serial communication with the Romi 32U4; however, we do not have any specific examples for that. If you use the control board’s hardware serial pins then you will not need any specific header files (although maybe there is some library out there that would make it easier to set up). Keep in mind though, it looks like the HC-06 uses a 3.3V logic level for its serial pins and the Romi 32U4 uses 5V logic, so you will need an appropriate voltage divider or a level shifter between the control board’s TX pin and your Bluetooth module’s RX pin.

- Patrick

thanks for the information!
by the way do you know any libraries for that?

Unfortunately, I do not know of any specific libraries that could be used for that. However, you might look into if your module’s manufacturer provides any libraries for it or if other people have written libraries for it.

- Patrick