https://devzone.nordicsemi.com/f/nordic-q-a/61041/nrf51-dongle-firmwareHi Accordingly to Datasheet: Both the nRF51 mbed interface FW and the J-Link OB image can be downloaded from www.nordicsemi.com. i have the mbed FW on my Dongle and want to switch it back to J-Link, i cant find exact .bin file on you homepageen-USTelligent Community 13Tue, 05 May 2020 11:36:46 GMThttps://devzone.nordicsemi.com/thread/248160?ContentTypeID=1Tue, 05 May 2020 11:36:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:53d36c0d-6e9a-4232-adbd-a9e130d2d145Ole Morten<p><a href="https://devzone.nordicsemi.com/members/kme">Kenneth</a> linked to <a href="https://devzone.nordicsemi.com/cfs-file/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-78af977bea0d43079bd920c9459551ca/J_2D00_Link-OB_2D00_SAM3U128_2D00_V2_2D00_NordicSemi-170724.bin">the file</a> <a href="https://devzone.nordicsemi.com/f/nordic-q-a/60758/nrf5x-ob-jlink-if-bin-is-not-longer-available-on-your-web-site">here. </a></p><div style="clear:both;"></div>