How to find the a connection identifier or Index to transmit Notifications on specific connection?

RE: How to find the a connection identifier or Index to transmit Notifications on specific connection?

ovrebekk — Wed, 27 Dec 2023 07:34:00 GMT

Hi Mohinish

Thanks for sharing your solution 🙂

I will close the ticket then.

Best regards
Torbjørn

RE: How to find the a connection identifier or Index to transmit Notifications on specific connection?

Mohinish — Wed, 27 Dec 2023 07:11:56 GMT

Hi,

In my case I couldn't pass struct bt_conn *conn pointer to high level applications as they have been ported from NRF5 SDK where the connection handler was 1 byte which was used to identify the central.

In Zephyr there is a bt_conn_index(curr_conn) API which returns the index of entry in table where connection struct is stored internally. But the problem is there is no API exposed which can return connection pointer from index. So I have found a work around for this which works for me.

/* Array to store the reference pointers of active connections*/

static struct bt_conn *connection_list[CONFIG_BT_MAX_CONN];

static void connected(struct bt_conn *conn, uint8_t err)

{

uint8_t conn_index;

struct bt_conn *curr_conn;

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));

curr_conn = bt_conn_ref(conn);

conn_index = bt_conn_index(curr_conn);

connection_list[conn_index] = curr_conn;

LOG_INF("Connected, index:%d, addr:%s", conn_index, addr);

}

static void disconnected(struct bt_conn *conn, uint8_t reason)

{

uint8_t conn_index;

char addr[BT_ADDR_LE_STR_LEN];

bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

conn_index = bt_conn_index(conn);

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

if (connection_list[conn_index]) {

bt_conn_unref(connection_list[conn_index]);

connection_list[conn_index] = NULL;

}

static void ble_app_read_data_over_connection_callback(struct bt_conn *conn, const uint8_t *const data, uint16_t data_len)

{

uint8_t conn_index = bt_conn_index(conn);

LOG_INF("ble_app_read_data: conn_index:%d, data_len:%d, data:%02X %02X %02X %02X", conn_index, data_len, data[0], data[1], data[2], data[3]);

// Route the data to high level Application.

app_router_msg_handler(conn_index, data, data_len);

}

void ble_app_write_data_over_connection(uint8_t conn_index, uint8_t *data, uint16_t data_len)

{

LOG_INF("ble_app_write_data: conn_index:%d, data_len:%d, data:%02X %02X %02X %02X", conn_index, data_len, data[0], data[1], data[2], data[3]);

if(connection_list[conn_index]) {

bt_nus_send(connection_list[conn_index], data, data_len);

} else {

LOG_ERR("Connection not present!!!");

}

RE: How to find the a connection identifier or Index to transmit Notifications on specific connection?

ovrebekk — Fri, 22 Dec 2023 14:51:32 GMT

Hi Mohinish

In NCS there should be a reference to the connection, of type struct bt_conn *conn, that will be provided when you receive data, and that you can set when you want to send the data.

Then you might need to map this pointer to other relevant data fields in your application, if you need to store some information for each of the connected phones.

Best regards
Torbjørn

RE: How to find the a connection identifier or Index to transmit Notifications on specific connection?

Mohinish — Fri, 22 Dec 2023 14:13:48 GMT

I am using NCS SDK v2.5.0.

RE: How to find the a connection identifier or Index to transmit Notifications on specific connection?

ovrebekk — Thu, 21 Dec 2023 10:03:21 GMT

Hi Mohinish

Which SDK version are you using?

There should be a connection handle associated with each link, yes, which you can use to separate the different central devices and make sure to return the response to the right one.

If you let me know which SDK version you are using I will try to provide some more specific pointers to where in the code you can find the handle.

Best regards
Torbjørn