Issue with Dynamic Advertising Data Update (Eddystone-UID) and Write Callback on NUCLEO-WB05KN

[burak_Guzeller]

Hi everyone,

I am working on a Beacon project using NUCLEO-WB05KN. My goal is to broadcast Eddystone-UID and allow a connected phone to update the Namespace ID and Instance ID via GATT characteristics.

The Setup:

• I have a Custom Service with two characteristics: Namespace (10 bytes) and Instance (6 bytes).

• The device broadcasts Eddystone-UID correctly in connectable mode.

• I’ve added the GATT_NOTIFY_ATTRIBUTE_WRITE (0x01) mask to both characteristics.

• I’m using hci_init(hci_user_evt_proc, NULL); for event handling.

The Problem:

1. When I write a value from the nRF Connect app, the write is successful on the phone side, but the aci_gatt_srv_attribute_modified_event callback is never triggered on the MCU side.

2. I have disabled EnterStopMode() to ensure the MCU stays awake.

3. I have tried implementing the callback in both app_stm32wb05n.c and stm32wb05n_events_cb.c (overriding the WEAK function), but still no luck.

My Device_Init Code:

C

/* Namespace Characteristic */
aci_gatt_srv_add_char_nwk(my_service_handle, UUID_TYPE_128, &ns_uuid, 10,
                          CHAR_PROP_READ | CHAR_PROP_WRITE | CHAR_PROP_WRITE_WITHOUT_RESP,
                          ATTR_PERMISSION_NONE,
                          0x01, // GATT_NOTIFY_ATTRIBUTE_WRITE
                          16, 1, &ns_char_handle);

Additional Code Snippets for Context

Main Loop & Process:

C

/* MX_STM32WB05N_Process is called inside while(1) in main.c */
void MX_STM32WB05N_Process(void)
{
  hci_user_evt_proc(); // Processing pending events
  User_Process();      // EnterStopMode() is commented out here
}

Advertising Configuration:

C

static void Start_Beaconing(void) {
  Advertising_Set_Parameters_t Advertising_Set_Parameters[1];

  /* Set to Connectable to allow GATT writes */
  aci_gap_set_advertising_configuration(0, GAP_MODE_GENERAL_DISCOVERABLE,
                                        HCI_ADV_EVENT_PROP_LEGACY | 
                                        HCI_ADV_EVENT_PROP_CONNECTABLE | 
                                        HCI_ADV_EVENT_PROP_SCANNABLE,
                                        250, 250, HCI_ADV_CH_ALL, HCI_ADDR_PUBLIC, NULL,
                                        HCI_INIT_FILTER_ACCEPT_LIST_NONE, 0, HCI_ADV_PHY_LE_1M, 0, HCI_ADV_PHY_LE_1M, 0, 0);

  /* current_adv_data is 31 bytes Eddystone-UID */
  aci_gap_set_advertising_data_nwk(0, ADV_COMPLETE_DATA, 31, current_adv_data);

  /* Scan response for Local Name */
  aci_gap_set_scan_response_data_nwk(0, ADV_COMPLETE_DATA, sizeof(scan_rsp), scan_rsp);

  Advertising_Set_Parameters[0].Advertising_Handle = 0;
  Advertising_Set_Parameters[0].Duration = 0;
  Advertising_Set_Parameters[0].Max_Extended_Advertising_Events = 0;
  aci_gap_set_advertising_enable(ENABLE, 1, Advertising_Set_Parameters);
}

My Question:

• Is there a specific registration step for callbacks in the STM32WB05 series that I am missing beyond hci_init?

• Should I use a different event mask for Write without response or Write Request to trigger the attribute modified event?

• Why would the stack accept the write but not propagate the event to the application layer?

Any help or example code for STM32WB05 specifically would be greatly appreciated.

[Imen.D · Accepted solution]

Hello @burak_Guzeller ,

You can refer to the SampleApp application within the X-CUBE-WB05N SW package:

\x-cube-wb05n\Projects\NUCLEO-U575ZI\Applications\UART\SampleApp\ for an example of  aci_gatt_srv_attribute_modified_event callback usage.

In this context on file Projects\NUCLEO-U575ZI\Applications\UART\SampleApp\STM32WB05N\App\gatt_db.c the following characteristic is defined: 

  STM32WB_memcpy(&char_uuid.Char_UUID_128, charUuidRX, 16);
  ret =  aci_gatt_srv_add_char_nwk(sampleServHandle, UUID_TYPE_128, &char_uuid, CHAR_VALUE_LENGTH, CHAR_PROP_WRITE | CHAR_PROP_WRITE_WITHOUT_RESP, ATTR_PERMISSION_NONE, GATT_NOTIFY_ATTRIBUTE_WRITE, 16, 1, &RXCharHandle);
  if (ret != BLE_STATUS_SUCCESS) { goto fail ;}

and on file Projects\NUCLEO-U575ZI\Applications\UART\SampleApp\STM32WB05N\App\app_stm32wb05n.c the following callback is triggered with the related user action: 

void aci_gatt_srv_attribute_modified_event(uint16_t Connection_Handle,
                                           uint16_t CID,
                                           uint16_t Attr_Handle,
                                           uint16_t Attr_Data_Length,
                                           uint8_t Attr_Data[])
{
  Attribute_Modified_CB(Attr_Handle, Attr_Data_Length, Attr_Data);
} /* end aci_gatt_attribute_modified_event() */

where the function Attribute_Modified_CB() for the RXCharHandle characteristic will simply allow to toggle a led within the receiveData() function: 

static void Attribute_Modified_CB(uint16_t handle, uint8_t data_length, uint8_t *att_data)
{
  if(handle == RXCharHandle + 1)
  {
    receiveData(att_data, data_length);
  }
 ...
}
 
static void receiveData(uint8_t* data_buffer, uint8_t Nb_bytes)
{
  BSP_LED_Toggle(LED2);

  for(int i = 0; i < Nb_bytes; i++)
  {
    PRINT_DBG("%c", data_buffer[i]);
  }
}

 Hope this helps you!