I am working on a peripheral / receiver project based on the nRF5340 audio application for SDK 2.5.1.
I have added the ability for the receiver to advertise and accept a connection from a central device.
This all works fine up to a certain point. After some time, the connection gets terminated by the receiver. I believe it's a known issue with controllers when both syncing to a broadcast stream and having an ACL connection at the same time.
The disconnecting issue aside, my central device cannot re-connect to the peripheral again after the disconnect, unless the receiver gets a reset. Here is what happens in my logs :
HL [00:01:09.882,537] <inf> bt_mgmt: Disconnected in bt_mgmt : 7F:A0:94:3D:DF:2E (random) : (reason 0x08) HL [00:01:09.882,568] <wrn> streamctrl_broadcast_sink: Unexpected/unhandled bt_mgmt event: 6 HL [00:01:09.883,666] <inf> bt_mgmt_adv: connectable extended advertising set created HL [00:01:09.883,758] <inf> broadcast_sink: Application disconnected: 7F:A0:94:3D:DF:2E (random) (reason 0x08) HL [00:01:09.883,758] <inf> broadcast_sink: Restarting advertising.. HL [00:01:09.884,674] <inf> bt_mgmt_adv: Advertising successfully started HL [00:01:10.136,108] <inf> bt_mgmt: Connected in bt_mgmt HL [00:01:10.136,199] <inf> bt_mgmt: Connected: 5F:B4:9C:F0:98:9D (random) HL [00:01:10.136,413] <wrn> streamctrl_broadcast_sink: Unexpected/unhandled bt_mgmt event: 2 HL [00:01:10.136,505] <inf> broadcast_sink: Application connected: 5F:B4:9C:F0:98:9D (random) HL [00:01:10.332,550] <inf> bt_mgmt: Disconnected in bt_mgmt : 5F:B4:9C:F0:98:9D (random) : (reason 0x3e)
This happens again and again when the central tris to re-connect after the receiver disconnects. It fails with reason 0x3e - BT_HCI_ERR_CONN_FAIL_TO_ESTAB .
Here are my connected and disconnected callback functions which are implemented in broadcast_sink.c :
static void connected(struct bt_conn *conn, uint8_t err)
{
char addr[BT_ADDR_LE_STR_LEN];
bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
if (err != 0U)
{
LOG_INF("Failed to connect to application %s (%u)", addr, err);
app_conn = NULL;
return;
}
app_conn = bt_conn_ref(conn);
if (app_conn == NULL)
{
LOG_ERR("connected - app_conn is NULL");
}
LOG_INF("Application connected: %s\n", addr);
}
static void disconnected(struct bt_conn *conn, uint8_t reason)
{
char addr[BT_ADDR_LE_STR_LEN];
bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
if (app_conn)
{
bt_conn_unref(app_conn);
app_conn = NULL;
}
LOG_INF("Application disconnected: %s (reason 0x%02x)", addr, reason);
LOG_INF("Restarting advertising..");
}
Also within the SDK , in bluetooth/bt_management/bt_mgmt.c, there are connected and disconnected callbacks which also get invoked before my own callbacks.
static void connected_cb(struct bt_conn *conn, uint8_t err)
{
LOG_INF("Connected in bt_mgmt");
int ret;
char addr[BT_ADDR_LE_STR_LEN] = {0};
uint8_t num_conn = 0;
uint16_t conn_handle;
enum ble_hci_vs_tx_power conn_tx_pwr;
struct bt_mgmt_msg msg;
(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
if (err) {
LOG_ERR("ACL connection in bt_mgmt to addr: %s, conn: %p, failed, error %d", addr,
(void *)conn, err);
bt_conn_unref(conn);
if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
ret = bt_mgmt_scan_start(0, 0, BT_MGMT_SCAN_TYPE_CONN, NULL);
if (ret) {
LOG_ERR("Failed to restart scanning: %d", ret);
}
}
if (IS_ENABLED(CONFIG_BT_PERIPHERAL)) {
//ret = bt_mgmt_adv_start(NULL, 0, NULL, 0, true);
ret = bt_mgmt_adv_start(ext_adv_buf, ext_adv_buf_cnt, NULL, 0, true);
if (ret) {
LOG_ERR("Failed to restart advertising: %d", ret);
}
}
return;
}
bt_conn_foreach(BT_CONN_TYPE_LE, conn_state_connected_check, (void *)&num_conn);
/* ACL connection established */
/* NOTE: The string below is used by the Nordic CI system */
LOG_INF("Connected: %s", addr);
if (IS_ENABLED(CONFIG_BT_CENTRAL) && (num_conn < MAX_CONN_NUM)) {
/* Room for more connections, start scanning again */
ret = bt_mgmt_scan_start(0, 0, BT_MGMT_SCAN_TYPE_CONN, NULL);
if (ret) {
LOG_ERR("Failed to resume scanning: %d", ret);
}
}
ret = bt_hci_get_conn_handle(conn, &conn_handle);
if (ret) {
LOG_ERR("Unable to get conn handle");
} else {
if (IS_ENABLED(CONFIG_NRF_21540_ACTIVE)) {
conn_tx_pwr = CONFIG_NRF_21540_MAIN_DBM;
} else {
conn_tx_pwr = CONFIG_BLE_CONN_TX_POWER_DBM;
}
ret = ble_hci_vsc_conn_tx_pwr_set(conn_handle, conn_tx_pwr);
if (ret) {
LOG_ERR("Failed to set TX power for conn");
} else {
LOG_DBG("TX power set to %d dBm for connection %p", conn_tx_pwr,
(void *)conn);
}
}
msg.event = BT_MGMT_CONNECTED;
msg.conn = conn;
ret = zbus_chan_pub(&bt_mgmt_chan, &msg, K_NO_WAIT);
ERR_CHK(ret);
if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
ret = bt_conn_set_security(conn, BT_SECURITY_L2);
if (ret) {
LOG_ERR("Failed to set security to L2: %d", ret);
}
}
}
static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
{
int ret;
char addr[BT_ADDR_LE_STR_LEN];
struct bt_mgmt_msg msg;
(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
/* NOTE: The string below is used by the Nordic CI system */
LOG_INF("Disconnected in bt_mgmt : %s : (reason 0x%02x)", addr, reason);
if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
bt_conn_unref(conn);
}
/* Publish disconnected */
msg.event = BT_MGMT_DISCONNECTED;
msg.conn = conn;
ret = zbus_chan_pub(&bt_mgmt_chan, &msg, K_NO_WAIT);
ERR_CHK(ret);
if (IS_ENABLED(CONFIG_BT_PERIPHERAL)) {
//ret = bt_mgmt_adv_start(NULL, 0, NULL, 0, true);
ret = bt_mgmt_adv_start(ext_adv_buf, ext_adv_buf_cnt, NULL, 0, true);
ERR_CHK(ret);
}
if (IS_ENABLED(CONFIG_BT_CENTRAL)) {
ret = bt_mgmt_scan_start(0, 0, BT_MGMT_SCAN_TYPE_CONN, NULL);
if (ret) {
LOG_ERR("Failed to restart scanning: %d", ret);
}
}
}
Any ideas as to why the central device can't reconnect here with error BT_HCI_ERR_CONN_FAIL_TO_ESTAB , until the receiver gets reset? The receiver and central device are right beside one another.
The receiver is clearly not in a right state to accept a new connection after it disconnects, but I'm not sure how to solve this. Thanks in advance for any help.
