https://devzone.nordicsemi.com/f/nordic-q-a/35246/fixed-time-interval-call-send-ble_nus_string_send-errorHi,guys. In my experiment, Firstly,I creat an app_timer work every 20ms interval APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_OP_QUEUE_SIZE, false); err_code = app_timer_create(&amp;m_timer_id, APP_TIMER_MODE_REPEATED, TIME_timeout_handler); APP_ERROR_CHECKen-USTelligent Community 13Tue, 12 Jun 2018 07:45:26 GMThttps://devzone.nordicsemi.com/thread/135678?ContentTypeID=1Tue, 12 Jun 2018 07:45:26 GMT137ad170-7792-4731-bb38-c0d22fbe4515:87f3180b-4dcc-4a67-8257-12d363b91359FormerMember<p>Good that you solved the problem!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/135646?ContentTypeID=1Tue, 12 Jun 2018 01:34:28 GMT137ad170-7792-4731-bb38-c0d22fbe4515:238eea29-240b-4a26-848e-d56114d80be4Jim_huan<p>14 . I find it and it work.Thanks.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/135500?ContentTypeID=1Mon, 11 Jun 2018 08:20:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b008ffa5-9faf-484f-891c-e8e916b17e12FormerMember<p>Which error code does ble_nus_string()/sd_ble_gatts_hvx() return?</p><div style="clear:both;"></div>