https://devzone.nordicsemi.com/f/nordic-q-a/39098/nrf51822-random-disconnection-problemHi to all, i am developing a device with nrf51822 soc. i am using nrf51822 custom board, my board is https://pl.aliexpress.com/item/2V-3-3V-NRF51822-Bluetooth-4-0-Wireless-Module-For-iBeacon-Base-Station-Intelligent-Control-System/32824004498.html en-USTelligent Community 13Tue, 02 Oct 2018 13:03:01 GMThttps://devzone.nordicsemi.com/thread/151248?ContentTypeID=1Tue, 02 Oct 2018 13:03:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f8145a1c-7b91-4840-b696-cbb6f7ee1093Einar Thorsrud<p>Hi,</p> <p>Disconnect reason 0x08 is Connection timeout (BLE_HCI_CONNECTION_TIMEOUT), which is caused by a connection supervision timeout. The main reasons are typically:</p> <ul> <li>Device goes out of range or a lot of noise.</li> <li>Optimistic connection parameters (too short connection supervision timeout relative to the connection interval) so that only a few packet drops will lead to disconnect.</li> <li>Clock drift between the peers.</li> </ul> <p>You can experiment to see if clock drift is the issue by setting a higher&nbsp;xtal_accuracy (for instance&nbsp;NRF_CLOCK_LF_XTAL_ACCURACY_250_PPM). This will increase the listening windows to give more margin. If the disconnects become less frequent with this setting, then you are on to something.</p> <p>The typical reason for the 32 kHz crystal to be off is improper value of the load capacitors. Which 32 kHz crystal do you use, and what is the value of your load caps?</p> <p>Br,</p> <p>Einar</p><div style="clear:both;"></div>