Using K_timer in Zephyr NCS 1.8.0 to initiate a BLE disconnection on Central

Question

Hello, 
 I am using nRF Connect SDK 1.8.0 on the nRF52840. I want to limit the amount of time that a peripheral can connect to my central 52840. On connection start I initiate a timer following the K_timer convention set by zephyr and it times out properly. I want to use the timeout handler function to call 
 int bt_conn_disconnect(struct bt_conn *conn, uint8_t reason) 
 
 I have used asynchronous functions to handle the connection and disconnection events but I had to register their callbacks using the struct static struct bt_conn_cb connection_callbacks . 
 Since there is no BLE event I'm timing out with, I wasn't sure how to get the bt_conn object to the timer's timeout handling function. I assume that the on_connected or on_disconnected events are receiving the bt_conn object through the event handler, but I was not sure about this. I tried to make the bt_conn object a static global var within the file, but in the timer handler the bt_conn_disconnect function fails with ENOTCONN (-128) so it seems it isn't accepting the bt_conn object correctly. 
 
 What would be the best way to correctly give the bt_conn object to the timer's timeout handling function here? 
 Thanks!

Kazi Afroza Sultana · Accepted Answer

Hello, 
 I am sorry as the first link was broken. Now you can check the link and also if you can find this in the NCS folder (nrf\samples\bluetooth\peripheral_uart). 
 If you declare the bt_conn object the way it is in the peripheral_uart sample, then it should act a global variable which can be used in your connection and disconnection function. Both connection and disconnection are defined from callback function. 
 
 static struct bt_conn *current_conn
--

static void connected(struct bt_conn *conn, uint8_t err)
{
	char addr[BT_ADDR_LE_STR_LEN];

if (err) {
 LOG_ERR("Connection failed (err %u)", err);
 return;
	}

bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
	LOG_INF("Connected %s", addr);

current_conn = bt_conn_ref(conn);

dk_set_led_on(CON_STATUS_LED);
}

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));

LOG_INF("Disconnected: %s (reason %u)", addr, reason);

if (auth_conn) {
 bt_conn_unref(auth_conn);
 auth_conn = NULL;
	}

if (current_conn) {
 bt_conn_unref(current_conn);
 current_conn = NULL;
 dk_set_led_off(CON_STATUS_LED);
	}
}

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
#ifdef CONFIG_BT_NUS_SECURITY_ENABLED
	.security_changed = security_changed,
#endif
}; 
 
 BR 
 Kazi

Using K_timer in Zephyr NCS 1.8.0 to initiate a BLE disconnection on Central

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