https://devzone.nordicsemi.com/f/nordic-q-a/56177/cannot-entry-in-function-write-callback-after-a-write-with-nrfconnectProject context: -------------------- Server BLE for home trainer diy Target (Bluetooth server) : Bluefruit nRF52 The feather Library : BluefruitBLE Client : nRF Connect (Android) Problem: ---------- I cannot entry the function callback on a writeen-USTelligent Community 13Mon, 06 Jan 2020 13:18:44 GMThttps://devzone.nordicsemi.com/thread/227679?ContentTypeID=1Mon, 06 Jan 2020 13:18:44 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d2c6ed9b-c0e7-44d6-ac41-192802fed097Kenneth<p>I tried to answer this in :<a href="https://devzone.nordicsemi.com/f/nordic-q-a/56188/general-question-about-the-gatt-concept-of-control-point">https://devzone.nordicsemi.com/f/nordic-q-a/56188/general-question-about-the-gatt-concept-of-control-point</a>&nbsp;</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/227517?ContentTypeID=1Sat, 04 Jan 2020 08:23:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6280ee12-b019-4cee-a8b2-18512715cb17Vincent25<p>Hi,</p> <p>Now I successfully entry the function callback.</p> <p>The reason was the permission which was unappropriate.</p> <p>But now I want to ask for informations about the handshake (flow chart) to implement for the server when a client write a control point.</p> <p>I didn&#39;t find any sample about this, and there is no detailled sequence diagram (uml) in the GATT specifications.</p> <p>I want to implement the Fitness Machine Control Point, but i think a lot of control point are built on the same template.</p> <p>Thank you</p> <p>best regards</p> <p>Vincent</p><div style="clear:both;"></div>