Issue with new characteristic handle value in ble_nus service

[EAkeila]

Hi,

I'm using nrf52840 with softdevice s140_nrf52_7.2.0  and I'm adding new characteristics to the ble_nus service. I've added the new handles for the new characteristics as follows:

ble_nus.h

struct ble_nus_s
{
    uint8_t                         uuid_type;          
    uint16_t                        service_handle;    
    ble_gatts_char_handles_t        rx_handles;        
	ble_gatts_char_handles_t        tx_handles;         
	ble_nus_data_handler_t          data_handler;      
		
	ble_gatts_char_handles_t        datetime_handles;    
	ble_gatts_char_handles_t        dataflash_handles;    
	ble_gatts_char_handles_t        username_handles;    
	ble_gatts_char_handles_t        autorecoding_handles;    
	blcm_link_ctx_storage_t * const p_link_ctx_storage;
};

I have initialized the new characteristics in the "ble_nus_init" function. The code seems to be working and I was able to see the new characteristics populated in nrfConnect App when I connect to the device. However, the problem is  I could not write the value of one of the characteristics when I write the value from the App. After debugging this I found the following:

1. when the firmware starts and calls ble_nus_init, I checked the handle value assigned at the end of the function for the new characteristics

2. When the connection is established, I checked these values again and I found that the handle value gets changed for the characteristic that has the issue (autorecording_handles):

This is changed from 0x0030 to 0x2565

3. When I try to write the value of the autorecording_handles from the App, I checked on_write function and I saw that the input "p_evt_write->handle" has the original value in step 1 (i.e. 0x0030). However, because the characteristic  handle value inside the firmware got changed after connection, then the condition to update the characteristic value inside the on_write  function does not get triggered. 

So I'm not sure why the characteristic handle value gets changed after connection in the first place!

[Jørgen Holmefjord]

Hi,

Can you post the full code showing implementation of the new characteristic, and the initialization of the handles?

Could it be that the handles are not declared static, and goes out of scope/being overwritten when the connect happens?

Best regards,
Jørgen

[EAkeila]

Hi Jorgen,

Sorry for my late reply. I discovered that all initializations have been done by external libraries used by a company we are working with. I'm following up with company. Thanks for your help!

Regards