Is write/notification reliable command? In other words: is there a chance that wiced_bt_gatt_send_write will return success but wont send my data and stack will silently drop it? A) Yes, its reliable. There is two types of write - write with response & without response. Write with response will ensure the data is received by the peer. This is handled in the BT stack. So there is no chance of silently dropping the data. Similarly for notification also there is no chance of dropping data , because stack will resend the packets if any packet loss happens. If you want to double confirm the data is received by the peer, you can use indication property instead of notification. Indication property will send ACK back after receiving the data from peer.
2. Does it support legacy pairing - can LTK be set by central to any value? A) 20819 supports pairing as per BLE spec. All this will be handled by BT stack
3. Can I use wiced_bt_gatt_send_write for both client and server? A) Generally a client will send write request / command to server. A server can send data to client by means of notify / indication
4. Can both advertise and scan while in a connection? A) Yes
5. Just to confirm - it supports simultaneous 3 central and 3 peripheral connections? A) yes it should be possible
Note: You may go through our WICED ACADEMY lab manuals for more details: