https://devzone.nordicsemi.com/f/nordic-q-a/101940/how-to-config-lescHi： I use SDK17.1.0. Example ble_app_hrs. Config: #define SEC_PARAM_LESC 1 /**&lt; LE Secure Connections enabled. */ #define SEC_PARAM_KEYPRESS 1 /**&lt; Keypress notifications not enabled. */ uint8_t const key[]=&quot;123456&quot;; ble_opt_t opt; opt.gap_opten-USTelligent Community 13Mon, 17 Jul 2023 11:22:20 GMThttps://devzone.nordicsemi.com/thread/436720?ContentTypeID=1Mon, 17 Jul 2023 11:22:20 GMT137ad170-7792-4731-bb38-c0d22fbe4515:38652ece-8ff4-438f-bcb7-2fc8f3a399bcVidar Berg<p>Hello,</p> <p>To enable passkey pairing with a static key, you can apply the following changes in main.c:</p> <p><a href="https://devzone.nordicsemi.com/cfs-file/__key/communityserver-discussions-components-files/4/hrs.diff">devzone.nordicsemi.com/.../hrs.diff</a></p> <p>Notice I changed the security level for the characteristics in service_init(). This forces the central to pair with your device before it can access the characteristics.&nbsp;</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>