How to identify two or more BLE devices

[ELEHM]

Hi, I have a question.

I am developing a BLE HIID device using the STM32WB55 evaluation board.
I am not sure how to identify multiple devices with the same firmware loaded.

The problem I am currently encountering is as follows ↓↓↓.

• Prepare two CFG_STATIC_RANDOM_ADDRESS and switch between them on each evaluation board.
• Two devices appear on the advice screen (windows pairing screen)
• If one is connected, the other cannot be connected.

I would appreciate it if you could tell me the cause of this phenomenon described above!

Thank you in advance.

[ELEHM]

The sample I am using is BLE_HID from STM32CubeWB.

/***
* Static random address
* The two upper bits shall be set to 1
* The lowest 32bits is read from the UDN to differentiate between devices
* The RNG may be used to provide a random number on each power on
*/
#if (CFG_IDENTITY_ADDRESS == GAP_STATIC_RANDOM_ADDR)
#if (CFG_STATIC_RANDOM_ADDRESS)
a_srd_bd_addr[0] = CFG_STATIC_RANDOM_ADDRESS & 0xFFFFFFFFFF;
a_srd_bd_addr[1] = (uint32_t)((uint64_t)CFG_STATIC_RANDOM_ADDRESS >> 32);
a_srd_bd_addr[1] |= 0xC000; /* The two upper bits shall be set to 1 */

The CFG_STATIC_RANDOM_ADDRESS here is changed for each evaluation board.

ret = aci_hal_write_config_data(CONFIG_DATA_RANDOM_ADDRESS_OFFSET, CONFIG_DATA_RANDOM_ADDRESS_LEN, (uint8_t*)a_srd_bd_addr);
if (ret ! = BLE_STATUS_SUCCESS)
{
APP_DBG_MSG(" Fail : aci_hal_write_config_data command - CONFIG_DATA_RANDOM_ADDRESS_OFFSET, result: 0x%x \n", ret); }
}
}
{
APP_DBG_MSG(" Success: aci_hal_write_config_data command - CONFIG_DATA_RANDOM_ADDRESS_OFFSET\n"); }
APP_DBG_MSG(" Random Bluetooth Address: %02x:%02x:%02x:%02x:%02x:%02x:%02x\n", (uint8_t)(a_srd_bd_addr[1] >> 8),
(uint8_t)(a_srd_bd_addr[1]),.
(uint8_t)(a_srd_bd_addr[0] >> 24),(uint8_t)(a_srd_bd_addr[0] >> 24),(uint8_t)(a_srd_bd_addr[1] >> ‌‌
(uint8_t)(a_srd_bd_addr[0] >> 16),(uint8_t)(a_srd_bd_addr[1])

(uint8_t)(a_srd_bd_addr[0])));
}

The write method probably hasn't been modified in any way

[STTwo-32 · Accepted solution]

Hello @ELEHM 

I think this should be due to the fact that Win10 doesn't accept different devices pair with the same IRK (Identity Root Key). So, I suggest you update the #define CFG_BLE_IRK on the app_conf.h file of your project and give a new value for each node. 

Best Regards.

STTwo-32 

[ELEHM]

Hello. @STTwo-32 

Thanks for the reply. I understand now.

Is there a problem with generating a 16 byte array for IRK when powering up in RNG, etc.? (Would the same process be required for LTKs?)

For example, as shown below↓↓

  CreateRandomNumbers(a_BLE_CfgIrValue, sizeof(a_BLE_CfgIrValue));
  ret = aci_hal_write_config_data(CONFIG_DATA_IR_OFFSET, CONFIG_DATA_IR_LEN, (uint8_t*)a_BLE_CfgIrValue);


static void CreateRandomNumbers(uint8_t *buffer,size_t length)
{
  uint32_t random32;
  /* Get RNG semaphore */
  while(LL_HSEM_1StepLock(HSEM, CFG_HW_RNG_SEMID));

  /* Enable RNG */
  __HAL_RNG_ENABLE(&hrng);

  /* Enable HSI48 oscillator */
  LL_RCC_HSI48_Enable();
  /* Wait until HSI48 is ready */
  while(! LL_RCC_HSI48_IsReady());

  for (size_t i = 0; i < length; i += 4)
  {
    if (HAL_RNG_GenerateRandomNumber(&hrng, &random32) != HAL_OK)
    {
      /* Random number generation error */
      Error_Handler();
    }
    buffer[i] = (random32 >> 24) & 0xFF;
    buffer[i + 1] = (random32 >> 16) & 0xFF;
    buffer[i + 2] = (random32 >>  & 0xFF;
    buffer[i + 3] = random32 & 0xFF;
  }

  /* Disable HSI48 oscillator */
  LL_RCC_HSI48_Disable();

  /* Disable RNG */
  __HAL_RNG_DISABLE(&hrng);

  /* Release RNG semaphore */
  LL_HSEM_ReleaseLock(HSEM, CFG_HW_RNG_SEMID, 0);
}