Connection parameters update failed, LMP TIMEOUT

Question

Hi, i am working on a bluetooth application with the nRF52832. When i try to connect a Samsung Galaxy S8 (Android 8.0) via nRF Connect, i get a LMP TIMEOUT error after 40 seconds (see LOG1). I do not get the error with a BQ Aquaris X5 Plus (Android 7.1.1) and Xiaomi Mi A1 (Android 8.0.0) (see LOG2). With a Samsung Galaxy A3 2017 (Android 7.0) i cant connect to the nRF52832 at all (Error 133 (0x85): GATT Error). The example ble_app_hrs from the SDK however works with all devices. I already tried to use different connection parameters without success. I am using SDK 14.0.0 with Softdevice 5.0.0. LOG1: I 10:58:01.256 Connected to D0:84:A2:77:D7:EB I 10:58:01.660 Connection parameters updated (interval: 7.5ms, latency: 0, timeout: 5000ms) I 10:58:02.753 Services discovered W 10:58:41.126 Connection parameters update failed with status 34 (interval: 7.5ms, latency: 0, timeout: 5000ms) E 10:58:41.127 Error 34 (0x22): GATT CONN LMP TIMEOUT D 10:58:41.139 [Callback] Connection state changed with status: 34 and new state: DISCONNECTED (0) E 10:58:41.140 Error 34 (0x22): GATT CONN LMP TIMEOUT I 10:58:41.140 Disconnected LOG2: I 13:48:21.941 Connected to D0:84:A2:77:D7:EB I 13:48:22.423 Connection parameters updated (interval: 7.5ms, latency: 0, timeout: 5000ms) I 13:48:23.554 Services discovered I 13:48:23.596 Connection parameters updated (interval: 48.75ms, latency: 0, timeout: 5000ms) I 13:48:27.201 Connection parameters updated (interval: 30.0ms, latency: 0, timeout: 3200ms) 
 Does anyone know how to fix the connection issues with the Samsung devices? 
 
 Thanks, 
 Andreas

Andreas123 · Answer

We fixed the issue by enabling the GATT module in sdk_config.h and adding a gatt_evt_handler() and gatt_init() to our main file.

arthare · Answer

I fixed this problem in my firmware by responding to the BLE_GAP_EVT_PHY_UPDATE_REQUEST message sent to my on_ble_evt handler. 
 case BLE_GAP_EVT_PHY_UPDATE_REQUEST:
 {
 ble_gap_phys_t const phys =
 {
 .tx_phys = BLE_GAP_PHY_AUTO,
 .rx_phys = BLE_GAP_PHY_AUTO,
 };
 ret_code_t err = sd_ble_gap_phy_update(pEvent->evt.gap_evt.conn_handle, &phys);
 APP_ERROR_CHECK(err);
 break;
 } 
 I had a Google Pixel 3A XL running Android 9, and every 30 seconds it would time out with the same complaints yours had.