Hi,
I’m streaming high-rate sensor data over BLE with an nRF52840 running NCS v2.9.0.
-
Data rate: 1 kHz, ≈ 8 400 B/s
-
Packing: 5 samples → 42-byte packet, pushed into an
msgq -
Sending: A dedicated thread dequeues the packets and transmits them with
bt_nus_send().
At very short range (0.3 – 0.5 m) everything is stable.
When the distance increases to 0.5 – 2 m, the msg gradually fills, and packet-loss grows with distance (≈ 2 % at 0.6 m, ≈ 32 % at 2 m). bt_nus_send() rarely returns an error, yet queue overflows and packet drops occur simultaneously.
Is such a sharp drop in throughput over this distance typical for the Nordic UART Service, or am I likely missing a configuration step (connection interval, PHY, MTU / DLE, flow control, etc.)?
Any recommendations on parameters or best practices to maintain ~8 kB/s without loss would be greatly appreciated.
the prj.conf as following:
# add BT peripheral rola support ad CONFIG_BT_PERIPHERAL=y # enable updata BT connect param CONFIG_BT_GATT_CLIENT=y CONFIG_BT_USER_PHY_UPDATE=y CONFIG_BT_GAP_AUTO_UPDATE_CONN_PARAMS=y CONFIG_BT_PERIPHERAL_PREF_MIN_INT=24 CONFIG_BT_PERIPHERAL_PREF_MAX_INT=24 CONFIG_BT_PERIPHERAL_PREF_LATENCY=0 CONFIG_BT_PERIPHERAL_PREF_TIMEOUT=400 CONFIG_BT_USER_DATA_LEN_UPDATE=y CONFIG_BT_CTLR_DATA_LENGTH_MAX=251 CONFIG_BT_BUF_ACL_RX_SIZE=251 CONFIG_BT_BUF_ACL_TX_SIZE=251 CONFIG_BT_L2CAP_TX_MTU=247 CONFIG_BT_CTLR_SDC_MAX_CONN_EVENT_LEN_DEFAULT=4000000 CONFIG_BT_CTLR_DATA_LENGTH_MAX=251 CONFIG_BT_KEYS_OVERWRITE_OLDEST=y CONFIG_BT_MAX_CONN=1 #Enable the NUS service CONFIG_BT_NUS=y
Thank you!
Best regards,
Ben
