Adding device identifier to BLE DFU application

[Krzysztof Cieniawski]

I am using bootloader based on Nordic secure bootloader example. I would like to add possibility to identify device after entering BLE DFU. I was thinking about device MAC address however this solution won't work with Apple devices as they don't have access to device address. I would like also to avoid editing Nordic libraries. Is there any possibility to achieve this or I am forced to edit DFU libraries?

[Sigurd]

Hi,

What device do you want to identify ?

Do you want to identify the nRF52 device, from the BLE central(e.g. a phone/computer) ?

or do you want to identify the BLE central(phone/computer), from the nRF52-device ?

[Krzysztof Cieniawski]

Hi Sigurd,

I would like to identify nRF52 device from BLE central. Phone is sending request to device to enter DFU what cause the device to disconnect and reboot as DFU device. In case of two devices in DFU mode with same name Apple mobile is not able to recognize its device. I would like phone to recognize the device to which should it send new application.

As far as I know DFU library doesn't provide way to customize name per device.

[Sigurd]

Hi,

When the nRF52 device enters bootloader mode, the bootloader starts to advertise with MAC address incremented by 1, so from the phone's perspective it's a completely new device. But if you know the old address, you only need to increment that with 1 to know the new address.

You can find our OTA DFU Library for Mac and iOS here: https://github.com/NordicSemiconductor/IOS-Pods-DFU-Library

[Krzysztof Cieniawski]

Sigurd, unfortunately iOS doesn't allow developers to obtain MAC address from advertising data. Device has to be identified in some other way e.g. adding custom field in manufacturer data. But does bootloader libraries allows customization advertising data without changes in code?

[mrono]

I believe there already is a command to specify the advertising name by writing to the Buttonless DFU control point characteristic. I think the Nordic DFU libraries use this in some cases, but I'm not sure when exactly.

I tried to find documentation but couldn't, so I'll point you to the source code:

In ble_dfu_unbonded.c check function ble_dfu_buttonless_on_crtl_pt_write(). There is a command called DFU_OP_SET_ADV_NAME. I think this is used to specify the name that the device advertises when in bootloader mode.

[Krzysztof Cieniawski]

mrono you are right. Buttonless DFU Service provided with Bluetooth SIG has command to setting bootloader advertising name after entering to it. I have found this few days ago and wanted to reply to my question but you were faster.

To sum up. Then developer is using bootloader prepared by Nordic then he set up advertising name with `#define` preprocessor directive. Easiest way to provide customizable bootloader advertising name is to provide Buttonless DFU Service in application. This service has two commands: first is for jumping into bootloader and second is for setting DFU target name after jumping. On the other hand this solution has some limitations, more informations: https://infocenter.nordicsemi.com => SDK => nRF5 SDK => Libraries => BLE Services => Buttonless Secure DFU Service