The Bluetooth device serial number is the GAP address.

[HaiMianBBao]

I used hidapi on Windows to enumerate Bluetooth HID devices and found that the serial number of the Bluetooth HID device is the Bluetooth GAP address, not the actual serial number.

[mcuee]

Have you check with other platforms like Linux or macOS?

[mcuee]

@HaiMianBBao

Please also provide more details of the device, thanks. Is it plain Bluetooth device or BLE device?

[HaiMianBBao]

I am very sorry, but I am unable to conduct tests on macOS and Linux systems. My device is a BLE HID device, and I can see the serial number using the nRF Connect app on my iPhone. However, the serial number enumerated by HIDAPI is the Bluetooth GAP address.

[HaiMianBBao]

static void hid_internal_get_ble_info(struct hid_device_info* dev, DEVINST dev_node)
{
	if (wcslen(dev->manufacturer_string) == 0) {
		/* Manufacturer Name String (UUID: 0x2A29) */
		wchar_t* manufacturer_string = (wchar_t *)hid_internal_get_devnode_property(dev_node, (const DEVPROPKEY*)&PKEY_DeviceInterface_Bluetooth_Manufacturer, DEVPROP_TYPE_STRING);
		if (manufacturer_string) {
			free(dev->manufacturer_string);
			dev->manufacturer_string = manufacturer_string;
		}
	}

	if (wcslen(dev->serial_number) == 0) {
		/* Serial Number String (UUID: 0x2A25) */
		wchar_t* serial_number = (wchar_t *)hid_internal_get_devnode_property(dev_node, (const DEVPROPKEY*)&PKEY_DeviceInterface_Bluetooth_DeviceAddress, DEVPROP_TYPE_STRING);
		if (serial_number) {
			free(dev->serial_number);
			dev->serial_number = serial_number;
		}
	}

	if (wcslen(dev->product_string) == 0) {
		/* Model Number String (UUID: 0x2A24) */
		wchar_t* product_string = (wchar_t *)hid_internal_get_devnode_property(dev_node, (const DEVPROPKEY*)&PKEY_DeviceInterface_Bluetooth_ModelNumber, DEVPROP_TYPE_STRING);
		if (!product_string) {
			DEVINST parent_dev_node = 0;
			/* Fallback: Get devnode grandparent to reach out Bluetooth LE device node */
			if (CM_Get_Parent(&parent_dev_node, dev_node, 0) == CR_SUCCESS) {
				/* Device Name (UUID: 0x2A00) */
				product_string = (wchar_t *)hid_internal_get_devnode_property(parent_dev_node, &DEVPKEY_NAME, DEVPROP_TYPE_STRING);
			}
		}

		if (product_string) {
			free(dev->product_string);
			dev->product_string = product_string;
		}
	}
}

wchar_t* serial_number = (wchar_t *)hid_internal_get_devnode_property(dev_node, (const DEVPROPKEY*)&PKEY_DeviceInterface_Bluetooth_DeviceAddress, DEVPROP_TYPE_STRING);

Is it related to this piece of code?

[Youw]

Yes, it seem so.
If you can suggest a correct way of getting the SN for BLE device that would be very helpful, thanks.