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User guide


You may need to update the firmware on your micro:bit to use features like WebUSB

What is firmware?

Hardware is the physical part of a micro:bit.

Software is made up of the programs you write and run on your micro:bit.

Firmware is in the middle: a special kind of software that makes devices function properly. It’s physically stored in the micro:bit’s interface chip and doesn’t change when you write programs or turn your micro:bit off, but it can be updated.

The micro:bit will work with the firmware it came with, but there may be times when you may want to update the firmware to use new features like WebUSB.

Checking your firmware version

To find out what version of the firmware you have on your micro:bit, Plug it in via USB, open up the DETAILS.TXT file from the MICROBIT drive and look for the number on the line that begins 'Interface Version'. In this example, the firmware version is 0250:

# DAPLink Firmware - see Unique ID: 9900000031634e4500624014000000320000000097969901
HIC ID: 97969901
Auto Reset: 1
Automation allowed: 0
Overflow detection: 0
Daplink Mode: Interface
Interface Version: 0249
Git SHA: 682d8303e37355532402b8d93c4f240a3cec02a9
Local Mods: 0
USB Interfaces: MSD, CDC, HID, WebUSB
Interface CRC: 0x3f2b7e12
Remount count: 0

How to update the firmware

  • Disconnect the USB cable and battery pack from the micro:bit.
  • Hold the reset button at the back of the micro:bit and plug the USB lead into the device. You should see a drive appear in your file manager called MAINTENANCE (instead of MICROBIT).
diagram of back of micro:bit board showing position of reset button next to USB socket
animation showing how to hold down reset button as you plug in the USB cable so it appears in maintenance mode
  • The MAINTENANCE drive will look like this, depending on your computer:


Windows screenshot showing how a micro:bit in maintenance mode appears as MAINTENANCE (D)


MacOS screenshot showing how a micro:bit in maintenance mode appears as a USB drive called MAINTENANCE
  • Download the hex file appropriate for your version of the micro:bit from this page to your computer. Read our article on identifying the micro:bit version, if you are unsure about which version you have.
  • Drag and drop the new firmware.HEX file you downloaded from this page onto the MAINTENANCE drive and wait for the yellow LED on the back of the device to stop flashing. When the upgrade is completed, the micro:bit will reset, ejecting itself from the computer and re-appear in normal MICROBIT drive mode.
  • Finally, check the DETAILS.TXT file that is on the MICROBIT drive and make sure that it has the same version number as the .HEX firmware that you just downloaded and flashed to the interface chip.
  • For any issues or help with the process of updating your firmware, please contact micro:bit support

Previous firmware versions

Should you wish to roll-back your micro:bit's firmware for any reason, you can find information on previous firmware versions in our developer documentation.