https://devzone.nordicsemi.com/f/nordic-q-a/123526/noticing-that-channel-map-updates-from-a-connected-phone-is-disabling-connection-subrating-on-my-nrf53-peripheralI have a peripheral which has an nRF53. It connects to either an Android of iOS phone. I&#39;ve been testing add Connection Subrating. However I&#39;ve been noticing that the Connection Subrating on the device keeps switching between my configured Subrating anden-USTelligent Community 13Thu, 07 Aug 2025 08:17:17 GMThttps://devzone.nordicsemi.com/thread/544885?ContentTypeID=1Thu, 07 Aug 2025 08:17:17 GMT137ad170-7792-4731-bb38-c0d22fbe4515:10eabc75-1bbc-4ec8-b698-46a022633e0eSusheel Nuguru<p>Hi Dave,&nbsp;</p> <p>Let me show you how I interpret the BLE spec Mostly in Vol 6 and Part B</p> <p>Section 5.1.2&nbsp;<br /><img alt=" " src="https://devzone.nordicsemi.com/resized-image/__size/1430x246/__key/communityserver-discussions-components-files/4/4061.pastedimage1754554252743v1.png" /></p> <p>Makes me interpret that LL_CHANNEL_MAP_IND PDU includes an instant parameter which is the connection event at which new channel map shall be used.</p> <p><img alt=" " src="https://devzone.nordicsemi.com/resized-image/__size/1282x794/__key/communityserver-discussions-components-files/4/7288.pastedimage1754554382092v2.png" /></p> <p>Here,&nbsp;(LL_SUBRATE_IND) is defined to use an Instant for the first sub‐rated anchor point, Agree?</p> <p>Section 5.3, says that twoo procedures are incompatible if both involve an instant.<br />Also&nbsp;<br /><img src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/7607.pastedimage1754554582658v3.png" alt=" " /></p> <p>Based on this my interpretation is that every time the phone’s controller sends an LL_CHANNEL_MAP_IND (to change the channel map “Instant”), the Link Layer must treat this as an incompatible new procedure and abort until you renegotiate again. And our samples is not demonstrating initiating renegotiations.</p><div style="clear:both;"></div>