How are CTS (0x1805) services discovered when acting as a GATT Server with an ESP32 GATT Client

Question

Hi, 
 I'm using a nrf52832 based beacon with some sensors attached. To retrive the current time I use the CTS client. Actually, I'm following the ble_app_cts_c example to advertise, then perform a db_discovery and, if available e.g. from an iPhone, update the time. 
 Now i'm trying to understand the way the esp32 (ISP-IDF v4.2) acting as a GATT client is asked for the time. There is no current time server, so char 0x1805 is not found at all. But, I don't see any request in the gattc callback function. 
 How is the process flow? Is the nrf52 (as soon as connected with all the security handled) asking the GATT client for the time? 
 On an iPhone everything is fine, NRF Connect app is obviously serving the time and nrf52 can retrieve this. 
 Regards 
 Andreas

Kenneth · Accepted Answer

Looking at the \ble_app_cts_c example I can find that the application is calling db_discovery_init() during initialization. 
 This means that on connection event with a peer the nRF52 will do a full database discovery of the peer. 
 In the project I can find that the ble_cts_c will register a callback if the current time service is found on the peer. This is done by calling ble_db_discovery_evt_register() in ble_cts_c_init(). This will ensure calling on_cts_c_evt() in main.c if found CTS is found on the peer. 
 What happens on the GAP central is unknown (not nordic implementation).

How are CTS (0x1805) services discovered when acting as a GATT Server with an ESP32 GATT Client

Top Replies