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FW-loader is a cross-platform command line tool you can use to easily switch back and forth between legacy KitProg2 and current KitProg3 on Cypress kits. KitProg3 extends the kits' capabilities and adds DAPLink support. Click the Release button to download the latest release. Source code for Firmware-loader is not available.

There is a package for each of the following operating systems:

  • linux

  • macos

  • windows

From the release page, download and unzip the appropriate zip archive for your OS. Open a command window in the tool's bin directory, and follow the instructions below.

On Linux OS, run the udev_rules\ script before the first run of the FW-loader.

Command-line Options

--help (or no arguments) - Displays the list of supported commands with their descriptions.

--device-list – Displays the list of connected devices.

--update-kp3 [device-name] – Updates the device FW to KitProg3.

--update-kp2 [device-name] – Updates the device FW to KitProg2.

The device name can be skipped if only one KitProg device is connected to the PC. Where a device name is required, use the device name from the "--device-list" command.


  1. KitProg2 supports two modes: Proprietary and CMSIS DAP. Only the Proprietary mode supports the bootloader. You must be in Proprietary mode for KitProg2 to be visible to the FW-loader. Use the Mode Switch button to switch KitProg2 to Proprietary mode.

  2. For KitProg3, use the Mode Switch (SW3) button to switch among KitProg3 bulk, KitProg3 HID, and DAPLink modes

  3. MiniProg4 does not support KitProg2 FW. The following symptoms show that KitProg2 FW is installed on MiniProg4:

    • The device is detected as MiniProg4 but does not operate.

    • Errors are observed while performing the --device-list command:

      • Error = Timeout of Response read for the "0x90" command. The number of attempts = 2.

      • Error = Out Endpoint is not found.

If the KitProg2 FW is installed on MiniProg4 - to restore the device functionality:

Switch the device to Bootloader mode:

- unplug MiniProg4 from the USB

- while pressing the Mode Select button on the kit, plug in the USB cable

- the Mode LED blinks to indicate the kit is in Bootloader mode

- release the button

Perform the "--update-kp3" command as described above.

More Information

Fw-loader Release Notes

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