what is the conn_handle? And when does it use?

[JoonDong]

I don't know where it is used..

example, when I use sd_ble_gatts_hvx(conn_handle, &p_hvx_params), conn_handle was BLE_GATT_HANDLE_INVALID(0x0000) result of debugging.

Why is conn_handle exist? although charateristic handle actually used is included in p_hvx_params.

[Hung Bui]

BLE_GATT_HANDLE_INVALID is for attribute handle, not connection handle. The first connection will have value of 0x0000. So it's normal. If you have more than one connection at the same time, for example in a central application with more than one peripheral, you will have different connection handles for different connections.

Do you have trouble using sd_ble_gatts_hvx() ?

[JoonDong]

So is conn_handle 0x0001 when connection event about second connection occurs if second connection is established?

[Hung Bui]

What do you mean by this "when connection event about second connection occurs " ? You don't have to guess/assume the conn_handle, you simply find it in the event you got, for example in BLE_GAP_EVT_CONNECTED event , look for p_ble_evt->evt.gap_evt.conn_handle, as Alex suggested.

[JoonDong]

I already checked p_ble_evt->evt.gap_evt.conn_handle during debugging, but value is always 0xFFFF or 0x0000..

[JoonDong]

So is it just assigned per each connection?