Over-the-Air Download (OAD)

The following sections aim to describe the lower layers of OAD software that are common across all protocol stack implementations. This includes the OAD image header, the flash layout, Boot Image Manager, and the oad_image_tool.

Warning

The BLE-Stack OAD Profile does not implement or perform any security or authentication mechanisms as part of the firmware update process. System developers should take measures to adequately authenticate peer devices and only accept and/or apply firmware images transferred from trusted sources via the OAD Profile. TI recommends applications use Bluetooth LE Secure Connections (LESC) with Man-in-the-Middle (MITM) protection with peer devices when performing wireless firmware updates, although the use of the LESC feature does not itself guarantee image authenticity.

When using the Secure OAD feature along with recommended parameters, firmware images are authenticated on the device using ECDSA signature validation algorithms to ensure image authenticity prior to updating the running firmware image. Just as with the OAD Profile, TI recommends applications use Bluetooth LE Secure Connections with Man-in-the-Middle (MITM) protection with peer devices when performing wireless firmware updates.

• Introduction
  • OAD Topology Overview
• OAD Storage & Security
  • OAD Storage
  • OAD Security
• Boot Image Manager (BIM)
  • Overview & Software Architecture
  • Boot procedure
    • Device trim
    • Halt In Boot (HIB)
  • Secure BIM
  • Locating and Preparing a user application
• BIM for Off-Chip OAD
• BIM for On-Chip OAD (Stack Library)
  • Application Execution switching using Validation Bytes in Flash
• OAD Image Header
  • OAD Image Header Overview
  • OAD Core Image Header
    • OAD Image Identification Value
    • CRC
    • BIM Version
    • Image Header Version
    • Wireless Technology
    • Image Information
    • Image Validation
    • Image Length
    • Program Entry Address
    • Software version
    • Image End Address
    • Header Length
  • OAD Image Header segments
    • Segment Header
      • Segment Type
      • Wireless Technology
      • Reserved
      • Payload Length
    • Boundary Information Segment
      • Stack Entry Address
      • Stack Boundary Address (ICALL_STACK0_ADDR)
      • Lower RAM Boundary (RAM_START_ADDR)
      • Upper RAM Boundary (RAM_END_ADDR)
    • Contiguous Image Information Segment
      • Image Start Address
    • Security Information Segment
      • Verification status
      • Security Version
      • Security Timestamp
      • Certificate Payload
• OAD External Flash Image Header
  • Additional Fields in External Flash Image Header
• Flash Layout for Off-Chip OAD
  • Requirements and Constraints for Off-chip OAD
  • Internal Flash Memory Layout
  • External Flash Memory Layout
• Flash Layout for On-Chip OAD
  • Constraints and Requirements for On-chip OAD (stack library)
  • Internal Flash Memory Layout
• OAD Image Tool
  • Running the tool
  • Running the Tool from Source
  • Generating New Security Keys (Embedded)
  • Required Arguments/Getting Help

The following sections aim to describe the BLE5-Stack specific application and profile layer of the OAD solution. The OAD application section will describe the BLE OAD process from a high level in terms of events and states, and the profile section will cover the actual structures that are sent over the air.

See Over the Air Download (OAD) Reference for more information about the various OAD APIs and structures.

• OAD Application
  • OAD Software Architecture
  • OAD State Machine
    • Image Validation
    • Image Block Transfers
    • Completion of the OAD Process
• BLE-Stack OAD Profile
  • Over the Air Message Sequence
  • OAD Service (0xFFC0)
    • OAD Image Identify (0xFFC1)
    • OAD Image Block Characteristic (0xFFC2)
    • OAD Control Point Characteristic (0xFFC5)
      • Get OAD Block Size CMD/RSP
      • Set Image Count CMD/RSP
      • Start OAD CMD/RSP
      • Enable OAD Image CMD/RSP
      • Cancel OAD CMD/RSP
      • Disable OAD Image Block Write CMD/RSP
      • Get Software Version CMD/RSP
      • Get OAD Image Status CMD/RSP
      • Get Profile Version CMD/RSP
      • Get Device Type CMD/RSP
      • Image Block Write Char RSP
      • Erase All Bonds REQ/RSP
  • OAD Reset Service (0xFFD0)
    • OAD Start/Reset Characteristic (0xFFD1)
  • OAD Return Values
  • OAD Block Size Rules

The SimpleLink Academy OAD Fundamentals Module covers the out of the box demo for OAD using the BLE5-Stack. It can be found here. This lab contains the following step by step instructions:

• Anatomy of an OAD

  • Image Header

  • Boot Image Manager (BIM)

  • OAD Memory Layout

  • OAD Protocol/BLE Profile

• Setting up the OAD Environment

  • OAD Distributor Setup

  • OAD Target Setup

  • Creating a Factory Image

• Running the OAD Demo

  • Modifying the Image Version

  • OAD using BTool

  • Btool Image Header Dialog

• Reverting to a Factory Image

The SimpleLink Academy OAD Advanced Module covers these advanced topics and instructions:

• Adding OAD to an Existing Project

  • Project Changes

  • Code Changes

• Advanced OAD Debugging

• Creating a Production Image

  • Change to Release BIM

  • Secure OAD: Change default keys

  • Loading a Production Image

  • Combined Production Image

Mobile developers wishing to make applications that integrate the TI OAD should refer to the following sample implementations. These are intended as reference libraries that implement the TI OAD Downloader for Android and iOS.

• ios-cocoapod-eoad.

• android-eoad

Note

The above libraries do not implement full fledged applications, but instead are intended to be integrated as part of an end application.