Refer to nordic ble central mutilink to modify zephyr ble connect, disconnection will cause problems （on nrf52840）

[hmw]

Since Zephyr’s official BLE sample code, his BLE central only supports one central to one peripheral
So I refer to the BLE central multulink officially provided by nordic to modify the zephyr example
The reference files are:
\nRF5SDK160098a08e2\examples\ble_central\ble_app_multilink_central

In addition, I also refer to other people’s examples of implementing one central to multiple peripherals
I referred from here https://github.com/zephyrproject-rtos/zephyr/issues/21552
I think his writing is very similar to the logic of Nordic’s BLE central multilink
I use this to modify, central will go to scan peripherals, after subscribing, in the notify function will receive the data sent by the peripheral, received and immediately use bt_gatt_write to send back to the peripheral directly
When I have more than two peripherals links, one of the peripherals is disconnected, it will print [UNSUBSCRIBED] and jump to the disconnect callback function, then clear the disconnected link, then do attempt_scan()
However, the connected peripheral cannot send the data to the central at this time, and the central will be stuck in the attempt_scan() of disconnect, and the transmission can only continue after the central finds(or connects again) the disconnected peripheral again
In theory, in central, disconnected peripherals will not affect the connected peripherals. Did I use the wrong method?
How to prevent central from getting stuck in diconnect's attempt_scan() so that the connected peripheral can still send information to central?

The disconnected callback function as follow:

static void disconnected(struct bt_conn *conn, u8_t reason)
{
	char addr[BT_ADDR_LE_STR_LEN];

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

    u8_t conn_index = bt_conn_index(conn);
    if (conn_index == connecting_index) {
        connecting_index = -1;
        is_connecting = false;
    }
    printk("Disconnected: %s, index: %u, ref: %u, (reason 0x%02x)\n", addr, conn_index, conn->ref, reason);

    if (conn_index < 32) {
        if (connections[conn_index] == conn) {
            bt_conn_unref(connections[conn_index]);
            connections[conn_index] = NULL;
            conn_num--;
        }
    }

    attempt_scan();
}

Thanks in advance,

PYL

[Edvin]

Hello,

If you want to support multiple connections in a zephyr project, you should set the CONFIG_BT_MAX_CONN in prj.conf to whatever number you want to support. Look at how this is set to 1 in the NCS\nrf\samples\bluetooth\peripheral_uart\prj.conf.

Other than that, you shouldn't mix source code from the nRF5 SDK and nRF Connect SDK (zephyr). They are not compatible.

The application in the peripheral_uart example is intended for only one connection, but you can look at the peripheral_hids_mouse example, which supports two connections, how you can handle multiple connections from your main.c file.

the peripheral_uart example has one pointer to the connection:

static struct bt_conn *current_conn;

while the peripheral_hids_mouse example has an array:

static struct conn_mode {
	struct bt_conn *conn;
	bool in_boot_mode;
} conn_mode[CONFIG_BT_HIDS_MAX_CLIENT_COUNT];

Best regards,

Edvin

[hmw]

Hello,
CONFIG_BT_MAX_CONN, I have already set it.
In addition, I did not mix nRF5 SDK and nRF Connect SDK (zephyr) together
I referred to the process of nrf5 sdk BLE multilink to make changes, sorry I didn’t make it clear
What is your version of zeohyr? I’m 2.4.99 and I didn’t see the folder peripheral_hids_mouse you mentioned, and I want to use a one central to multiple peripherals
Thank,

PoYi,Lin

[Edvin]

I use NCS (nRF Connect SDK) v1.4.0. Try that one. You can find it here:

https://github.com/nrfconnect/sdk-nrf

The sample is found in the path:

NCS\nrf\samples\bluetooth\peripheral_hids_mouse

Best regards,

Edvin

[hmw]

Thank you for your offer
But I currently want to do multilink on central
And it’s like only peripherals code
Is there an example of central multilink?

Thanks,

Poyi

[Einar Thorsrud]

Hi Poyi,

The only examples of multilink central in NCS is the dongle for nRF Desktop.

Einar