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How to Revive a “Bricked” Cactus Micro

Incorporating all of the USB tasks on a single chip is an awesome feature that makes the Cactus Micro and boards like it truly unique. But it also places more stress on a single chip, and if anything goes wrong with that chip, the board becomes nearly unusable. It’s not uncommon for Cactus Micro’s to become “bricked” and unprogrammable. But, in most cases, the bricking is reversible!

The most common source of Cactus Micro “bricking” is uploading code to it with an incorrectly set board.

To revive the Cactus Micro, you’ll need to find a way to upload a sketch to it with the board option correctly set. We can do this with a little help from the bootloader.

First, you’ll need to set the serial port to the bootloader. But that port is only visible when the board is in bootloader mode, so pull the reset line low twice quickly to invoke the bootloader reset feature discussed above. You can quickly press the reset button twice. While the Cactus Micro is in the bootloader change the ‘Tools > Serial Port’ menu to the bootloader COM port. Quick! You’ve only got eight seconds. On Windows, the bootloader’s COM port number is usually one number higher than the Cactus Micro’s regular port number.


Why Does my ATMega32U4 Board Show up Twice in Device Manager?

Both the bootloader and the sketch have their own VID/PIDs. When you plug in a board the bootloader starts running for a few seconds, and you will see the board show up in Device Manager based on those VID/PIDs. After a few seconds, the sketch will start running, and you will see Device Manager disconnect from the bootloader and connect to the sketch.

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Contributors: yanc