Device Firmware Upgrade (DFU) Mode

Last Update: Feb 11, 2020 @ 15:04 : Preliminary Information subject to change.

All PiXCLe Decaf™ boards are supplied preloaded with application firmware, and can be easily reloaded by the end user if this becomes necessary. The process used for this is called Device Firmware Upgrade, or simply, DFU. This means that

  • a board does not have to shipped back to us for reloading, unless there is an actual hardware problem.
  • you can upgrade or downgrade the firmware version when we release a new one.

The DFU tools are not shipped with the board kits, but are freely available to all users from the download links in the Support Pages. You are issued a UserID/Password after purchase of product.

We provide a pair of easy-to-use utilities that can completely reload a non-functional board, or just upgrade the PiXCLe application.


This utility loads the core DFU firmware into the Decaf™ boards via the COM connection. This only needs to be done once. Thereafter, the DFU mode is used for all upgrades. Note this refers to the 72MHz IOC boards that use the Cortex-M3 mpu. Recent models such as the IOC-280Z-4 use the Cortex-M4 mpu which has the DFU mode built in.


This utility can be called by the USB mode of Flash_Loader, to download PiXCLe original or upgrade firmware directly via the USB port.

DFU Process Summary

A firmware upgrade is most commonly an update to the USB, RTOS or  PiXCLe interpreter version, and might include bug fixes and new command options. These are a binary file with the extension DFU.

DFU is recognized as a specific USB device class by the host PC, and there is a driver, part of the product installation, that has to be loaded to support this. When the DFU Upgrade application is started, it searches for and identifies all Decaf™ boards attached to the PC, and sends a command to switch the board into DFU mode. This has the effect to disconnecting the board’s SD card (if present and supported) as a Mass Storage Device, and is normal operation.

You next select the desired .DFU binary file (upgrade or downgrade), and this is then downloaded to the board, which takes about 20 seconds. When the DFU Upgrade application is closed, the Decaf™ board resets and the new firmware is now operational.

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