DFU over a serial USB connection

This DFU method uses a USB Communications Device Class-Abstract Control Model (USB-CDC-ACM) connection for the Device Firmware Update (DFU).

Note

This procedure is compatible only with chips that have USB pins (for example, nRF52840).

The USB port for the interface MCU is not connected to the USB pins on the chip. If you are using the interface MCU, you must perform a DFU over a serial UART connection.

Related nRF5 SDK documentation

Secure DFU Bootloader over Serial Link (UART/USB) Example

You can run the nrfutil nrf5sdk-tools dfu usb-serial command to perform this update, together with appropriate options for your setup. To see the list of options, run the nrfutil nrf5sdk-tools dfu usb-serial --help command.

Complete the following steps to perform the DFU:

Connect the DFU target to your computer. If your DFU target is an nRF52840 DK, use the USB port marked nRF USB.
Run nrfutil nrf5sdk-tools dfu usb-serial to do a full DFU procedure over a USB CDC ACM connection.

For example, enter the following command to perform a DFU procedure of the file app_dfu_package.zip over COM3 at 115200 bits per second:
```
nrfutil nrf5sdk-tools dfu usb-serial --package app_dfu_package.zip --port COM3 --baud-rate 115200
```
In this command:
- --package specifies the package to be transferred.
- --port specifies the serial port to which the DFU target is connected.
- --baud-rate specifies the baud rate for the serial connection.