1.3.1 How the SPI Bootloader Library Works

The SPI Bootloader firmware communicates with the embedded host device by using a predefined communication protocol.

The SPI Bootloader works in two different modes:

Basic Mode

• This mode is supported for all the devices

• Resides from:

  • The starting location of the Flash memory region for Cortex-M based MCUs

• The Bootloader performs Flash erase/program/verify operations with the binary sent from host while in the Firmware Upgrade mode

  • The binary sent is only of the application to be programmed
  • Bootloader always performs Flash operation from the address for (bootloader or application) binary sent from host
  • The application can use the entire Flash memory region starting from the end of bootloader space

• Jumps to the application once verification is completed

Fail Safe Update Mode

• This mode is supported for the devices which have a Dual Bank Flash memory

• Resides from the starting location of the Flash memory region of both the banks on Cortex-M based MCUs

• The Bootloader performs Flash erase/program/verify operations with the binary sent from host while in the Firmware Upgrade mode

  • Bootloader can perform Flash operation in either of the banks based on the address sent by the host application

  • The application can use only the Flash memory region of one bank

• Performs a bank swap and reset to run the application programmed in opposite bank once verification is completed or a normal reset to run the application in current bank based on command sent from host