https://devzone.nordicsemi.com/f/nordic-q-a/124227/how-to-change-the-usb-iserialnumberHi Nordic Teams: I&#39;m using Nordic Connect SDK v3.1.0 and nRF52840, I want to update USB iSerialNumber string in hid-keyboard samples. I tried two methods but they didn&#39;t work. One was to change the &#39;CONFIG_USB_DEVICE_SN&#39;, and the other was toen-USTelligent Community 13Mon, 22 Sep 2025 17:52:29 GMThttps://devzone.nordicsemi.com/thread/549464?ContentTypeID=1Mon, 22 Sep 2025 17:52:29 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9d82f3af-bbde-4ca1-baaf-e0a00692f191tesc<p>Hi,</p> <p>The <a href="https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/samples/subsys/usb/hid-keyboard/README.html#usb-hid-keyboard">USB HID keyboard sample</a> uses a new (experimental) USB device See <a href="https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/connectivity/usb/device_next/usb_device.html">New USB device support</a> for details. With that stack, by default the Serial Number is fetched from the <a href="https://docs.nordicsemi.com/bundle/ps_nrf52840/page/ficr.html#register.DEVICEID-0">DEVICEID register in FICR</a>. There is a macro for Serial Number, <a href="https://docs.nordicsemi.com/bundle/zephyr-apis-latest/page/group_usbd_api.html#ga26af7f93205dc78eeb60a3c09aa7b2d3">USBD_DESC_SERIAL_NUMBER_DEFINE</a>, but it is hard wired to the DEVICEID.</p> <p>The methods that you tried were for the old stack. With the old stack, you can change the Serial Number by setting CONFIG_USB_DEVICE_SN or overriding usb_update_sn_string_descriptor(). Some samples, such as the <a href="https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/samples/subsys/usb/hid-mouse/README.html#usb-hid-mouse">USB HID mouse sample</a>, still uses the old USB device stack, where those methods are available.</p> <p>Regards,<br />Terje</p><div style="clear:both;"></div>