The peripheral is disconnected from the central when a second vendor specific UUID service is added

[Norbert Czupor]

Hello, Could someone give me a hint with the following problem?

I am using two example projects (ble_app_uart_c, ble_app_hrs) to connect a central and a peripheral. An UUID is added to the peripheral (former ble_app_hrs) in order to support an additional service (device state). With this configuration the central is able to establish a stable connection and read the changes of the new service. The service discovery looks like this:

But when I add a second characteristic to the peripheral the connection is disconnected after the registration. The new service discovery looks like this:

When observing the central the disconnection takes place shortly after the following event(s):

…

BLE_GATTC_EVT_DESC_DISC_RSP

BLE_GATTC_EVT_WRITE_RSP

BLE_GATTC_EVT_HVX --> on_hvx(...)

… and the reason was timeout for the disconnection.

Any ideas ? I guess it’s a simple beginners error but I’ve spent many days to look through the forum and documentation but without success …

I addition I enclose the stack init function of the central:

static void ble_stack_init(void)
{
    uint32_t err_code;
    uint32_t app_ram_base;

    // Initialize the SoftDevice handler module.
    SOFTDEVICE_HANDLER_INIT(NRF_CLOCK_LFCLKSRC_XTAL_20_PPM, NULL);
    
    // Enable BLE stack.
    ble_enable_params_t ble_enable_params;
    memset(&ble_enable_params, 0, sizeof(ble_enable_params));
#if (defined(S130) || defined(S132))
	  // Attribute Table size in bytes. The size must be a multiple of 4. @ref BLE_GATTS_ATTR_TAB_SIZE_DEFAULT is used to set the default size. 
	  ble_enable_params.gatts_enable_params.attr_tab_size = BLE_GATTS_ATTR_TAB_SIZE_DEFAULT;
#endif

	  ble_enable_params.common_enable_params.vs_uuid_count = 8; // Maximum number of 128-bit, Vendor Specific UUID bases to allocate
	  ble_enable_params.gatts_enable_params.service_changed = false; //IS_SRVC_CHANGED_CHARACT_PRESENT; // Include the Service Changed characteristic in the Attribute Table
    ble_enable_params.gap_enable_params.central_conn_count = CENTRAL_LINK_COUNT; // Number of central links
    ble_enable_params.gap_enable_params.central_sec_count = 0; // Number of SMP (Security Manager Protocol, security request) instances for all the central links
    ble_enable_params.gap_enable_params.periph_conn_count = PERIPHERAL_LINK_COUNT; // Number of peripheral links
	
    app_ram_base = __LINKER_APP_RAM_BASE;
    err_code = sd_ble_enable(&ble_enable_params, &app_ram_base);
    if(err_code == NRF_SUCCESS)
    {
      // Verify that __LINKER_APP_RAM_BASE matches the SD calculations 
      if(app_ram_base != __LINKER_APP_RAM_BASE)
      {
#ifdef RTT_DBG
			  SEGGER_RTT_printf(0,"Warning: unused memory: 0x%x\r\n", __LINKER_APP_RAM_BASE - app_ram_base);
			  nrf_delay_ms(DEFAULT_NRF_ERROR_DELAY); 
#endif		
      }
    } else 
	  { if(err_code == NRF_ERROR_DATA_SIZE)
		  { // Not enough memory for the SoftDevice. place a breakpoint here or output app_ram_base
#ifdef RTT_DBG
			  SEGGER_RTT_printf(0,"Fatal: Not enough memory for the selected configuration. Required: 0x%x\n\r", app_ram_base);
		  } else
			{ SEGGER_RTT_printf(0,"Error: The function 'sd_ble_enable()' failed, code = %d\n\r", err_code);	
			}
			nrf_delay_ms(DEFAULT_NRF_ERROR_DELAY); 
#endif		
		  APP_ERROR_CHECK(err_code);
    }
			
    // Register with the SoftDevice handler module for BLE events.
    err_code = softdevice_ble_evt_handler_set(ble_evt_dispatch);
    APP_ERROR_CHECK(err_code); 
}