Entering USB DFU Mode

To enter the USB DFU mode, perform the following steps:

1. Connect RUMBA32 to the host computer via a micro USB cable.
2. Press and hold RUMBA32 BOOT button.
3. Press and release RUMBA32 RESET button.
4. Release RUMBA32 BOOT button.

This will place the board into bootloader mode. If the USB connection is detected by the board, it will enter USB DFU mode and the on-board LED will flash once.

One way to check that RUMBA32 is detected and that the correct drivers have been loaded is to look for the board in the Windows Device Manager. Open Device Manager (Start Search > Device Manager). With RUMBA32 connected via USB and in DFU mode, RUMBA32 should appear under Universal Serial Bus devices as STM32 BOOTLOADER:

If you can't see RUMBA32 there, look for it under a different heading in the Device Manager. If you disconnect/reconnect RUMBA32 (or reset it), and bring it back into DFU mode, Device Manager should flash and update as it detects the device disconnecting & reconnecting.

If RUMBA32 appears under a different device name when in USB DFU mode, then it is likely that the wrong drivers are being loaded by Windows. This can be corrected by the following steps:

1. Download Zadig. Zadig is a tool for changing the driver on USB devices.
2. Open Zadig, and click Options > List all Devices. The dropdown select in the main window should then have a list containing all of the USB devices attached to your computer.

3. Select the list item that corresponds to RUMBA32. Once selected, check the USB ID boxes - they should read 0483 and DF11. If that is the case, this confirms you have selected RUMBA32 (or another device with the same microcontroller - which is unlikely).

4. Make sure that the right-hand box (the one with the arrow pointing to it) has WinUSB selected. If not, scroll through the options until WinUSB is selected.
5. Press the large button - this should say Replace Driver or Reinstall Driver, depending on whether or not WinUSB was already in use.
6. Wait for the process to finish - this shouldn't take longer than a minute at most.
7. Go back to the Device Manager, and check that you can locate RUMBA32 under the STM32 BOOTLOADER name.