BLE connection error

Development setup:

• 2 x nRF52840 SoC
• Our own PCB’s with inverted F-antenna
• LE PHY 1M
• nRF Connect SDK v1.8.0

Hi,

During testing we experience an issue which seems to be related to the central and peripheral being on the edge of range.

The test setup is a single central and a single peripheral with log output to UART. The distance between the two devices is chosen so the devices continuously connects and disconnects. The central upon connection subscribes to sensor data on several services. The peripheral samples a sensor and notifies the data. Below you find part of the log file. 

15-06-2022 01:57:29.786 [RX] - [18:21:20.569,732] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:35.112 [RX] - [18:21:25.916,4
15-06-2022 01:57:35.128 [RX] - 42] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:37.048 [RX] - [18
15-06-2022 01:57:37.069 [RX] - :21:27.852,996] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:39.260 [RX] - [18:21:30.0
15-06-2022 01:57:39.281 [RX] - 64,605] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:40.904 [RX] - [18:21:31.687,744] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:43.319 [RX] - [18:21:34.122,772]
15-06-2022 01:57:43.335 [RX] -  <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:46.293 [RX] - [18:21:37.077,911] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:49.570 [RX] - [18:21:40.353,759] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:55.071 [RX] - [18:21:45.855,346] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:57.013 [RX] - [18:21:47.797,943] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:57:59.045 [RX] - [18:21:49.84
15-06-2022 01:57:59.066 [RX] - 8,541] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:02.296 [RX] - [18:21:53.080,230] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:04.414 [RX] - [18:21:55.196,685] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:07.435 [RX] - [18:21:58.218,566] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:10.672 [RX] - [18:22:01.454,895] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:13.339 [RX] - [18:22:04.123,199] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:16.058 [RX] - [18:22:06.859,558] <wrn> bt_
15-06-2022 01:58:16.074 [RX] - hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:29.158 [RX] - [18:22:19.961,63
15-06-2022 01:58:29.184 [RX] - 9] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:20.075,714] <wrn> bt_hci_core: opcode 0x200a status 0x09

15-06-2022 01:58:31.196 [RX] - [18:22:21.962,554] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:21.962,829] <wrn> bt_hci_core: opcode 0xfc0e status 0x02
[18:22:22.963,104] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:22.963,348] <wrn> bt_hci_core: opcode 0xfc0e status 0x02

15-06-2022 01:58:33.164 [RX] - [18:22:23.963,623] <wrn> bt_hci_core: o
15-06-2022 01:58:33.200 [RX] - pcode 0xfc0f status 0x02
[18:22:23.963,867] <wrn> bt_hci_core: opcode 0xfc0e status 0x02
[18:22:24.964,172] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:24.964,416] <wrn> bt_hci_core: opcode 0xfc0e status 0x02

15-06-2022 01:58:34.272 [RX] - [18:22:25.
15-06-2022 01:58:34.304 [RX] - 075,836] <err> bt_conn: not connected!
[18:22:25.964,691] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:25.964,935] <wrn> bt_hci_core: opcode 0xfc0e status 0x02

15-06-2022 01:58:36.199 [RX] - [18:22:26.965,240] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:26.965,515] <wrn> bt_hci_core: opcode 0xfc0e status 0x02
[18:22:27.965,789] <wrn> bt_hci_core: opcode 0xfc0f status 0x02
[18:22:27.966,033] <wrn> bt_hci_core: opcode 0xfc0e status 0x02

The problem is that the central no longer has connection with the peripheral and a power cycle of the central does not help.

The peripheral seems to think that it is in a connection, and therefore does not start advertising again.

Best regards,

Annette