Changing base UUID of Nordic UART service causes it to stop working

[Primož Kralj]

I have successfully set up UART/Serial Port Emulation over BLE example. I have modified it so that it works with two nRF51 DKs, one acting as a central and other acting as a peripheral.

The base UUID for this service by default is

{0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0, 0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E}

but I would like to use my own base UUID. For starters, I tried changing just one word (4th, 0x22):

{0x9E, 0xCA, 0xDC, 0x22, 0x0E, 0xE5, 0xA9, 0xE0, 0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E}

I made sure that new UUID is the same on both projects, central and peripheral. However, after this change, the DK's won't even pair anymore.

What am I missing?

[Petter Myhre]

The base UUID is actually defined twice in ble_app_uart_c_S120.

Once in ble_uart_c_init():

ble_uuid128_t   nus_base_uuid = {{0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0, 0x93, 0xF3, 0xA3, 0xB5, 0x00, 0x00, 0x40, 0x6E}};

Once in main.c:

uint8_t   nus_service_uuid[16] = {0x9E, 0xCA, 0xDC, 0x24, 0x0E, 0xE5, 0xA9, 0xE0,
                                     0x93, 0xF3, 0xA3, 0xB5, 0x01, 0x00, 0x40, 0x6E};

I'm guessing you didn't make the modification in both places?

I'm not sure why it is made like this, I'll have a talk with the developer.

[Anders Strand]

nus_service_uuid is the complete 128 bit service UUID for NUS (combined base uuid and 16 bit service uuid). This is only used to compare uuid's from advertisement packets, to the uuid you are interested in. The nus_base_uuidis added to the softdevice using sd_ble_uuid_vs_add(&nus_base_uuid, &uart_uuid.type). It is then used by for example the db_discovery module by referencing the uart_uuid.type