Attaching Custom 128 bit Characteristic UUIDS to Custom 128 bit Service UUID where the base does not match

[only1chi]

Hi,

I am trying to emulate a vendor's tool, whose BLE properties are configured as follows:

Custom 128 bit Service UUID like XXXXXXXX-0000-XXXX-XXXX-XXXXXXXXXXXX

Custom 128 bit Characteristic UUID like XXXXXXXX-0001-XXXX-XXXX-XXXXXXXXXXXX

There are five more characteristics like this. 

With the nrf5 SDK, it appears that I can add a characteristic to a service with a base UUID, but it will modify the 12th and 13th octet. In other words, when I try to add the characteristic to the service, I end up with a UUID that looks like this: XXXX0001-XXXX-XXXX--XXXX-XXXXXXXXXXXX

This is not what I want. 

Is there a way to add a characteristic with a completely different 128 bit UUID base to a service, without having to add a new service to the gatt table?
I don't want to create 6 different services just so I can have a characteristic with a different base UUID.

Thanks.

[only1chi]

Hi,

Thank you. Your suggestion worked. I can now see all my 6 characteristics attached to the same service.

Chiz

[only1chi]

I do have one more question:

My application has three services, including battery service and device information service.
In my main.c file, I try to add the services, along with my custom service for advertising. However, this causes a crash.
This is the piece of code that adds my service uuid. How do I make my custom service advertise its UUID? 

// YOUR_JOB: Use UUIDs for service(s) used in your application.
static ble_uuid_t m_adv_uuids[] =                                               /**< Universally unique service identifiers. */
{
    {BLE_UUID_DEVICE_INFORMATION_SERVICE, BLE_UUID_TYPE_BLE},
    {BLE_UUID_BATTERY_SERVICE, BLE_UUID_TYPE_BLE},
    {BLE_UUID_VECTOR_PUMP, BLE_UUID_TYPE_VENDOR_BEGIN}
};

[Kenneth]

What have you configured to NRF_SDH_BLE_VS_UUID_COUNT to?

Have you tried to debug to find where the error code that is causing the crash is coming from? Typically by checking app_error_fault_handler().

[only1chi]

I configured NRF_SDH_BLE_VS_UUID_COUNT count to 7. 
The failure happens in during advertising initialization, in function ble_advdadta_encode. 
The failure goes away if I don't include my custom service in the m_adv_uuids[] array. 

[Kenneth]

I think you are trying to put to much data into the advertising packet, and you get an error due to size. 

Have you tried to debug to find where the error code that is causing the crash is coming from? Typically by checking app_error_fault_handler().

[only1chi]

Hi Kenneth,

I don't think that too much data is the problem.

The error code is 

NRF_ERROR_INVALID_PARAM

This is from the function

sd_ble_uuid_encode(&uuid, &encoded_size, NULL)

I don't quite understand why this function is returning an error_code = 7;

[Kenneth]

I recommend to check out some of the threads with similar problems:

https://devzone.nordicsemi.com/f/nordic-q-a/17312/nrf52-returning-error-code-7-when-trying-to-set-proprietary-uuid-in-advertising-data

The description from the error code is:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.s132.api.v7.0.1/group___b_l_e___c_o_m_m_o_n___f_u_n_c_t_i_o_n_s.html#ga2e55f7d7e631d072c24f2d6bc0860cc8

NRF_ERROR_INVALID_PARAM

Invalid UUID type.

[only1chi]

I did finally figure it out looking at other posts. As it turns out, I was not registering my base uuid. I fixed this by calling services_init() function first before calling advertising_init().