Flash the latest standard firmware directly from your browser. The normal update flow now stays on this page.
Hold Your Critters! Read the instructions for your OS before starting. The main update button below now tries the automatic bootloader handoff first when your Critter supports it.
Note: This tool uses WebUSB, which requires Chrome or another Chromium browser. WebUSB is not supported on iPhone or iPad.
Normal flow: click Start Standard Update, approve any browser prompts, and follow the status messages here.
If your device is already on recent firmware, this page will try to reboot it into bootloader mode automatically before flashing.
Initializing...
Only use this if you want to reboot into bootloader without starting the full update yet.
The bootloader update flow is now isolated on its own page so it cannot interfere with the standard firmware updater.
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Quickest path: click Start Standard Update first. On compatible firmware, the page will prompt for your Critter's USB serial port and reboot it into bootloader mode automatically.
If that automatic handoff does not work, use one of the manual bootloader methods below, then come back to the same button.
~CAT BOOTLOADER MODE~
Connect to a computer over USB
to download new firmware.
Power → Sleep. Once it is asleep, use the "Sleepy Wake-up" method above.Once the bootloader screen is showing, plug the Critter into your computer or phone and continue with the standard update button on the left.
Why the refreshes later? μCritter uses a two-stage MCUboot flow. Your browser may need a refresh between stages so it can reconnect to the device cleanly.
Mac pals, follow the status messages next to the Start Standard Update button. It is still a connect-refresh-connect routine, but the bootloader helper now lives in the same card.
MCUBOOT and click Connect.
CAT PROTOTYPE? Your Critter is not in bootloader mode yet. Go back to Step 1 and try again.MCUBOOT again.Did it work? Keep an eye on the progress log. "Pupdate Complete!" means success and your Critter will reboot with the new firmware.
Because Windows needs a little extra help recognizing your Critter during the update, you need a one-time Zadig driver setup and a restart sequence. Please follow these steps exactly.
Options and enable List All Devices.MCUBOOT from the dropdown list (USB ID 2FE3 0100).
Interface Check: Pick the entry for Interface 2. Do not replace the driver for Interface 0.
Seeing CAT PROTOTYPE instead of MCUBOOT? Go back to Step 1 and re-enter bootloader mode.
WinUSB for Interface 2.MCUBOOT in the browser pop-up.MCUBOOT again from the dropdown.
MCUBOOT device.MCUBOOT in the browser pop-up when asked.Watch the progress log. "Pupdate Complete!" means success and your Critter will restart automatically.
Linux usually needs a quick one-time udev rule so the browser can talk to the Critter.
You only need to do this once per computer.
sudo nano /etc/udev/rules.d/51-mcuboot.rulesSUBSYSTEM=="usb", ATTR{idVendor}=="2fe3", ATTR{idProduct}=="0100", MODE="0666", GROUP="plugdev"
SUBSYSTEM=="usb", ATTR{idVendor}=="2fe3", ATTR{idProduct}=="ffff", MODE="0666", GROUP="plugdev"
groups and see whether plugdev is listed.sudo usermod -aG plugdev $USERsudo udevadm control --reload-rules && sudo udevadm triggerThis command creates the file, adds your user, and reloads the rules:
echo -e 'SUBSYSTEM=="usb", ATTR{idVendor}=="2fe3", ATTR{idProduct}=="0100", MODE="0666", GROUP="plugdev"\nSUBSYSTEM=="usb", ATTR{idVendor}=="2fe3", ATTR{idProduct}=="ffff", MODE="0666", GROUP="plugdev"' | sudo tee /etc/udev/rules.d/51-mcuboot.rules > /dev/null && sudo usermod -aG plugdev $USER && sudo udevadm control --reload-rules && sudo udevadm trigger && echo "Rule created or updated. Log out/in if you were not already in plugdev."
Snap or Flatpak Chromium? You may also need explicit USB access. For Snap Chromium, try sudo snap connect chromium:raw-usb.
MCUBOOT and click Connect.
CAT PROTOTYPE? Bootloader mode is not active yet.Watch the progress log. "Pupdate Complete!" means success and your Critter will reboot.
You must use Google Chrome on Android for WebUSB to work reliably.
Then follow the messages next to the Start Standard Update button:
MCUBOOT when Chrome asks for permission.
CAT PROTOTYPE? Your Critter is not in bootloader mode yet.MCUBOOT.Keep an eye on the progress log. "Pupdate Complete!" means your Critter is ready to reboot and show off.