1.5.2 Serial Memory Bootloader Execution Flow

• On device reset after System initialize, the Bootloader task starts executing from the SYS_Tasks()

• Once the Serial Memory driver is ready, it retrieves the Meta Data from serial memory

  • If any error in reading the Meta Data it directly jumps Run application

• It checks if the Meta Data read is valid using the Prologue and Epilogue.

  • If valid:

    • It stores the application start address and application size from meta data which will be used during programming operation

    • Checks if the Update Required flag is set. If set it jumps to Programming step or continues to Trigger Check

  • If Invalid:

    • It continues to Trigger Check

Trigger Check

• If there are no conditions to enter the Firmware Upgrade mode, the Bootloader jumps to Run application
  • Refer to the Bootloader Trigger Methods for different conditions to enter Firmware Upgrade mode

Programming

• Starts reading the application binary from serial memory and perform erase/program operations on internal Flash

• Once programming is completed, it generates CRC32 on programmed space of internal Flash and verifies it against the CRC32 value stored in Meta data

• Once verification is complete it clears the update required flag in meta data and triggers reset to Run application

Run Application

• The application start address used to jump to application space can be:

  • Application start address generated during compile time or

  • Application start address retrieved from valid Meta Data

• Calls SYS_DeInitialize() function to release resources used

• Jumps to application space to run the updated application