https://devzone.nordicsemi.com/f/nordic-q-a/6967/keil4-no-jlink-device-foundI have a nRF51-DK and SDK8+Keil5. I also have a module that sadly uses an old revision 1 nrf51822. It is connected via SWD to my nRF51-DK. I could programm it with keil 5. I can programm it with nrfgo studio. But to use SDK5 I have installed KEIl4en-USTelligent Community 13Sun, 22 Oct 2017 22:03:07 GMThttps://devzone.nordicsemi.com/thread/24575?ContentTypeID=1Sun, 22 Oct 2017 22:03:07 GMT137ad170-7792-4731-bb38-c0d22fbe4515:344a6925-1b27-4df6-b90c-2ad5f3aea1f0Daniel Sullivan<p>Very sorry about the thread dig (mods please feel free to delete and reprimand me):</p> <p>For anyone else coming across this issue through Google search, it seems there&#39;s something weird about the JLink DLL that comes with different versions of Keil. Managed to fix by installing the JLink tools directly from Segger</p> <p><a href="https://www.segger.com/downloads/jlink/#J-LinkSoftwareAndDocumentationPack">www.segger.com/.../</a></p> <p>Let the installer overwrite the Keil DLL, run the JLink Commander app and let it do any firmware updates it wishes. Keil should then see it fine.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/24574?ContentTypeID=1Fri, 08 May 2015 13:52:22 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3958bf30-05f4-40d4-946a-e94c201b4bf4muhkuhns<p>Well that was easy. Hitting Repair on nrfTools after installation of Keil4 solved the problem!</p><div style="clear:both;"></div>