How to add add, insert and remove BLE services dynamically at run time and if I have to send multiple data under one service

[Ayu7]

if I have to send multiple data under one service 

like: Service 1(Information)

Hardware Revision String

Model Number String, the

Regulatory Certification Data List 

Then what should be the proper format (like string, array, individually or something else) of sending data? 

[Hung Bui]

Hi Ayu,

Any data sending over BLE is a byte array. 

So you can either make different characteristic for each of the data you want to send. Or you can use one single characteristic and send all data via this characteristic. 
You can simply use the first byte in the array to tell which type of data containing in the array. 

[Ayu7]

Ok, but you missed first question, that 

How to add add, insert and remove BLE services dynamically at run time

[Hung Bui]

Hi Ayu, 

You only need service changed indication if you update the attribute table when you are already in a connection. 

To do that, you would need to the service changed characteristic (included by default) then you need to call sd_ble_gatts_service_changed() to send the indication. 
Please take a look at this ticket: RE: I give up; how do I do a service changed? 

The example  you should have a look is ble_app_gatts

[Ayu7]

Hi Hung, thanks for last response,

1- Currently I have used two dks one for peripheral and one for client but I am not able to understand the seral monitor result. Can you explain.

2- And how to do same by  nrf connect app and dk.

3- So, what I am understanding is  when ever I am clicking button 3, a new service is getting created and client is discovering it with NRF_BLE_GATTS_C_EVT_DISCOVERY_COMPLETE and then notify that service changed received with NRF_BLE_GATTS_C_EVT_SRV_CHANGED. But let say I don't want click the Button 3 or any button and want to add services on peripheral side dynamically then how to do this. any reference or example?

[Hung Bui]

Hi Ayu, 
Sorry for late response. We are under reduced staff in the summer. 

1. Please study the code and check where the log is printed. 

2. Please verify if you can add new service by using a phone to see after you add a service would you have more service when you disconnect and then connect. 

3. I don't really understand you. If you don't want to click a button, you can change the code to do it based on something else, timer or other event. I don't see any limitation on why you can't change that. 

[Ayu7]

Thanks Hung Bui , I understood the output. Also I am able to add custom services and characteristics dynamically. But still every time I need to refresh the nrfconnect application to see the newly added characteristics. Can I automate it, can I send any notification that new characteristics has been added, so that app can refresh it.  I want to know about peripheral side rather than client(mobile) side. Can you please help me in this.

[Hung Bui]

Hi Ayu, 

There is a button in NRF Connect called "Refresh service" (click on 3 dots) you can click that to have the service discovery again. 

If you develop your own app you can automate it.

Have you sent service changed indication ? If you did, I believe you can get the indication from the app and can automatically do service discovery again. 

[Ayu7]

Hi, I called this function :  

void our_service_change(ble_os_t * p_our_service)
{
uint32_t err_code_2;

static uint16_t start_handle= 0x000B;
const uint16_t end_handle = 0xFFFF;

err_code_2 = sd_ble_gatts_service_changed(p_our_service->conn_handle,
start_handle,
end_handle);

APP_ERROR_CHECK(err_code_2);
}

but its showing 12291 error.

[Hung Bui]

Hi again, 
When you see an assert , please try to do debugging. 

12291 = 0x3003 and it's equal to BLE_ERROR_INVALID_ATTR_HANDLE

In the description of sd_ble_gatts_service_changed you can find this: 

[Ayu7]

Hung Bui I know the error but don't know what to do

[Hung Bui]

You need to find the correct start handle of your attribute table. 
One option is to follow what we did in gatts_cache_manager.c ( in ble_app_gatts.c example)

It simply tries calling sd_ble_gatts_service_changed ()  and increase the start handle if BLE_ERROR_INVALID_ATTR_HANDLE returns.