Pyboard Firmware Update

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You can download the latest firmware from


First, disconnect everything from your pyboard. Then connect the DFU pin with the 3.3V pin (they're right next to each other) to put the board into DFU (Device Firmware Update) mode. Now connect the pyboard to your computer via USB. DFU pin quick reference



First, install dfu-util via your package manager.

You can list all DFU-capable devices using the -l argument:

$ sudo dfu-util -l
dfu-util 0.5

(C) 2005-2008 by Weston Schmidt, Harald Welte and OpenMoko Inc.
(C) 2010-2011 Tormod Volden (DfuSe support)
This program is Free Software and has ABSOLUTELY NO WARRANTY

dfu-util does currently only support DFU version 1.0

Found DFU: [0483:df11] devnum=0, cfg=1, intf=0, alt=0, name="@Internal Flash  /0x08000000/04*016Kg,01*064Kg,07*128Kg"
Found DFU: [0483:df11] devnum=0, cfg=1, intf=0, alt=1, name="@Option Bytes  /0x1FFFC000/01*016 e"
Found DFU: [0483:df11] devnum=0, cfg=1, intf=0, alt=2, name="@OTP Memory /0x1FFF7800/01*512 e,01*016 e"
Found DFU: [0483:df11] devnum=0, cfg=1, intf=0, alt=3, name="@Device Feature/0xFFFF0000/01*004 e"

If desired, backup the original firmware (this doesn't work with dfu-util 0.5, but does with 0.7 or newer). Previous releases of micropython are available from: so performing a backup shouldn't be necessary.

$ sudo dfu-util --alt 0 --upload pyboard-original.dat -s:524288
Starting upload: [#######] finished!

Then write the downloaded firmware to the pyboard:

$ sudo dfu-util --alt 0 -D pybv10-2014-05-19-v1.0.1-24-g5cdff5f.dfu 
done parsing DfuSe file


If you have other DFU capable devices connected to you machine (for example an Apple Magic Mouse), and you receive the following message:

More than one DFU capable USB device found, you might try '--list' and then disconnect all but one device

you may want to disconnet all other devices, or specify which device's firmware you want to edit by passing either --device or the shorter -d flag to dfu-util. Example:

$ sudo dfu-util --alt 0 -D pybv10-2014-05-19-v1.0.1-24-g5cdff5f.dfu -d 0483

After the the program finished, disconnect the pyboard from USB and remove the jumper between the DFU and the 3.3v ports.

If you need to restore the original firmware, use the following command:

$ sudo dfu-util --alt 0 -D pyboard-original.dat -d 0483:df11 -s 0x8000000

This will restore everything, including the internal flash filesystem.


There is an alternative DFU programmer that is written in pure Python. It can be found here: . It requires the PyUSB package.

To use pydfu:

$ python -u <firmware.dfu>

This will copy the given firmware file to the pyboard. pydfu is much faster than dfu-util.


  • libusb (MacPorts: port install libusb or HomeBrew: brew install libusb)
  • PyUSB (pip install pyusb)

On Windows

See this PDF document: Micro-Python-Windows-setup.pdf

Firmware version

Once you have flashed the new firmware you may want to check it correspond to the version expected. At the REPL prompt, type

>>> import os
>>> os.uname()