iOS DFU Library

Installation

For Cocoapods(Swift): Using Obj-C? Use these instructions instead

• Create/Update your Podfile with the following contents

  target 'YourAppTargetName' do
      use_frameworks!
      pod 'iOSDFULibrary'
  end
  

• Install dependencies

  pod install
  

• Open the newly created .xcworkspace

• Import the library to any of your classes by using import iOSDFULibrary and begin working on your project

For Carthage:

• Create a new Cartfile in your project's root with the following contents

  github "NordicSemiconductor/IOS-Pods-DFU-Library" ~> x.y //Replace x.y with your required version
  

• Build with carthage

  carthage update --platform iOS //also OSX platform is available for macOS builds
  

• Carthage will build the iOSDFULibrary.framework and Zip.framework files in Carthag/Build/, you may now copy all those files to your project and use the library, additionally, carthade also builds *.dsym files if you need to resymbolicate crash logs. you may want to keep those files bundled with your builds for future use.

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Device Firmware Update (DFU)

The nRF5x Series chips are flash-based SoCs, and as such they represent the most flexible solution available. A key feature of the nRF5x Series and their associated software architecture and S-Series SoftDevices is the possibility for Over-The-Air Device Firmware Upgrade (OTA-DFU). See Figure 1. OTA-DFU allows firmware upgrades to be issued and downloaded to products in the field via the cloud and so enables OEMs to fix bugs and introduce new features to products that are already out on the market. This brings added security and flexibility to product development when using the nRF5x Series SoCs.

This repository contains a tested library for iOS 8+ platform which may be used to perform Device Firmware Update on the nRF5x device using an iPhone or an iPad.

DFU library has been designed to make it very easy to include these devices into your application. It is compatible with all Bootloader/DFU versions.

Service Changed characteristic

In order the DFU to work with iOS, the target device MUST have the Service Changed characteristic with Indicate property in the Generic Attribute service. Without this characteristic iOS will assume that services of this device will never change and will not invalidate them after switching to DFU bootloader mode.

To enable Service Changed characteristic for nRF5 application make sure this flag is set in your main.c file:

#define IS_SRVC_CHANGED_CHARACT_PRESENT 1

Service Changed characteristic behaviour:

• On paired devices a change of the attribute table must be indicated using an indication to the Service Changed characteristic. iOS automatically enables the CCC and handles this indication and performs a service discovery. This indication is handled correctly in Legacy DFU since SDK 8.0.
• On non-trusted devices (not paired) iOS will clear the service cache every time the device disconnects.

Secure DFU from SDK 12:

• The Secure DFU implementation from SDK 12 does not support bonding (experimental buttonless sample does not pass bond information when switching to DFU bootloader mode and the bootloader does not send S-C indication). As a workaround, the bootloader starts to advertise with MAC address incremented by 1, so from the phone's perspective it's a completly new device and a fresh service discovery will be done. When your new firmware is going to change the list of services you may consider adding another 1 to the MAC address for the new application to make sure the cache will not conflict (unless the device is not bonded and you have Service Changed characteristic, then no caching is used as written above). Be aware, that adding 1 to a public address does not guarantee its uniqness. Also, devices may be sold with following MAC addresses and it may happen that 2 devices have the same one. Use this feature carefully.

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Documentation

See the documentation for more information.

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Requirements

The library is compatible with nRF51 and nRF52 devices with S-Series Soft Device and the DFU Bootloader flashed on.

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DFU History

Legacy DFU

• SDK 4.3.0 - First version of DFU over Bluetooth Smart. DFU supports Application update.
• SDK 6.0.0 - DFU Bootloader supports Soft Device and Bootloader update. As the updated Bootloader may be dependent on the new Soft Device, those two may be sent and installed together.
• SDK 6.1.0 - Buttonless update support for non-bonded devices.
• SDK 7.0.0 - The extended init packet is required. The init packet contains additional validation information: device type and revision, application version, compatible Soft Devices and the firmware CRC.
• SDK 8.0.0 - The bond information may be preserved after an application update. The new application, when first started, will send the Service Change indication to the phone to refresh the services. New features:

• Buttonless update support for bonded devices
• sharing the LTK between an app and the bootloader.

Secure DFU

• SDK 12.0.0 - New Secure DFU has been released. This library is fully backwards compatible so supports both the new and legacy DFU.

Check platform folders for mode details about compatibility for each library.

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Resources

• DFU Introduction
• Secure DFU Introduction
• How to create init packet
• nRF51 Development Kit (DK) (compatible with Arduino Uno Revision 3)
• nRF52 Development Kit (DK) (compatible with Arduino Uno Revision 3)