Hello,
We are observing intermittent connection failures when using two nRF54L15 DK boards. Occasionally the connection fails with the warning:
<warn> bt_conn: conn 0x20015708 failed to establish. RF noise?
We first observed this in our channel sounding application and initially suspected it was related to our implementation. However, after further investigation we were able to reproduce the same behavior using the standard Zephyr central and peripheral samples in NCS 3.2.3. It occurs less frequently in this setup, but still appears roughly 1 in 100 connection attempts.
Setup
Two nRF54L15 DKs on a desk
Distance < 0.5 m
SDK: nRF Connect SDK 3.2.3
Reproduction
samples/bluetooth/central and samples/bluetooth/peripheral, but modified so the central only connects to specific peripheral address and the peripheral so it restarts advertisement after disconnect.
Central sample modification
// prj.conf
CONFIG_LOG=y
CONFIG_LOG_DEFAULT_LEVEL=3
// main.c
static const bt_addr_le_t target_addr = {
.type = BT_ADDR_LE_RANDOM,
.a = {{0x41, 0x21, 0xC2, 0xFC, 0x8C, 0xD8}}
};
if (bt_addr_le_cmp(addr, &target_addr) != 0) {
return;
}
Peripheral sample modification
// prj.conf
CONFIG_BT_PRIVACY=y
// main.c
static struct k_work adv_restart_work;
static void adv_restart_work_handler(struct k_work *work)
{
int err;
err = bt_le_adv_start(BT_LE_ADV_CONN_FAST_1, ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));
if (err) {
printk("Advertising failed to restart (err %d)\n", err);
} else {
printk("Advertising restarted\n");
}
}
static void disconnected(struct bt_conn *conn, uint8_t reason)
{
printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
k_work_submit(&adv_restart_work);
}Is this a known issue or errata with the nRF54L15 DK or the current Bluetooth controller/stack in NCS 3.2.3?
We have not observed this behavior previously with other Nordic boards such as the nRF52840.
