https://devzone.nordicsemi.com/f/nordic-q-a/20788/which-softdevice-do-i-need-to-download-when-i-m-using-the-newest-sdkHi, I&#39;m have a question : If i download s120 or s130 softdevice, which SDK version i need to download ? Which version is compatible with my nrf51822xaa ? The reason is when i use some newer SDK , my program can not load into my kit. Thank you !en-USTelligent Community 13Sun, 26 Mar 2017 08:31:50 GMThttps://devzone.nordicsemi.com/thread/81184?ContentTypeID=1Sun, 26 Mar 2017 08:31:50 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0a83204d-ef25-471e-9ce9-086b3048db60lilymeow<p>Thanks to your answer, i&#39;d known which version i need to use in my project, the problem solved . Thank you !</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/81183?ContentTypeID=1Sat, 25 Mar 2017 10:05:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:661399ff-af22-4222-aad8-72ba98742666endnode<p>Hi, you should use some of supported combinations of Soft Device + SDK + chip version (= HW board):</p> <ul> <li><a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf51/dita/nrf51/pdflinks/nrf51_comp_matrix.html?cp=3_0">nRF51 compatibility matrix</a></li> <li><a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/nrf52_comp_matrix.html?cp=2_0">nRF52 compatibility matrix</a></li> </ul><div style="clear:both;"></div>