https://devzone.nordicsemi.com/f/nordic-q-a/43776/bootloader-usb-fails-to-enumerate-device-on-windows-10-nrf-54820-development-kitHi there, nRF52840-Preview-DK, 0.9.3 2017.43 nRF5_SDK_15.2.0_9412b96 IAR for ARM 7.60.1 Windows 10 Home Version 1803 OS build 17134.590 When I try to run secure_bootloader_usb_mbr_pca10056 and enter into DFU mode, I get notification from Windows &quot;USBen-USTelligent Community 13Tue, 19 Feb 2019 20:26:41 GMThttps://devzone.nordicsemi.com/thread/171982?ContentTypeID=1Tue, 19 Feb 2019 20:26:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:7f22a3f1-34d2-4d1c-97d6-2d0e8d17f823Cecylia<p>Thanks Sigurd! &nbsp;I&#39;ll just try it on our production PCB directly then <span class="emoticon" data-url="https://devzone.nordicsemi.com/cfs-file/__key/system/emoji/1f642.svg" title="Slight smile">&#x1f642;</span></p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/171703?ContentTypeID=1Mon, 18 Feb 2019 16:05:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:52ec8736-4895-4233-a301-4a2c05ea633aSigurd<p>Hi,</p> [quote userid="12462" url="~/f/nordic-q-a/43776/bootloader-usb-fails-to-enumerate-device-on-windows-10-nrf-54820-development-kit"]nRF52840-Preview-DK, 0.9.3 [/quote] <p>This PDK version uses&nbsp;a engineering A revision of the nRF52840.</p> <p><span>From SDK 15, the support for engineering A devices were dropped. See this <a href="https://www.nordicsemi.com/DocLib/Content/Comp_Matrix/nRF52840/latest/COMP/nrf52840/nRF52840_ic_rev_sdk_sd_comp_matrix">compatibility matrix</a>. I would strongly recommend that you develop on a nRF52840-DK, as this uses the production silicon.</span></p><div style="clear:both;"></div>