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# 1.9 OTA Bootloader

The OTA bootloader Library can be used to upgrade firmware on a target device without the need for an external programmer or debugger.

Features

- Supported on Cortex-M and MIPS based MCUs, and MPUs

- For MCUs, Bootloader uses dual bank Flash memory or external memory to store the application image

  - Dual Bank Flash Memory: Uses Harmony 3 NVM/NVMCTRL/EFC peripheral library to communicate with the internal dual bank Flash memory

  - External Memory: Uses Harmony 3 Serial Memory drivers to communicate with the associated serial memory. Below are the serial memory drivers used.

    - I2C EEPROM: AT24 Driver

    - SPI EEPROM: AT25 Driver

    - SPI Flash: SST26 Driver

    - QSPI Flash: SST26 Driver

- For MPUs, Bootloader uses SD Card/NAND/Serial Flash memory to store the OTA application image

OTA Bootloader With Dual Bank Flash Memory (For MCUs)

- Bootloader Task (Dual Bank):

  - Uses Harmony 3 NVM/NVMCTRL/EFC peripheral library to read the control block (Metadata) stored in dual bank Flash memory

  - Checks for update in control block (Metadata)

  - Updates control block (Metadata) in dual bank Flash memory, swap bank and trigger reset

  - Jumps to the Application

  - Runs in Cooperative mode with other tasks in the system

OTA Bootloader With External Memory (For MCUs)

- Bootloader Task (External Memory):

  - Uses Serial Memory driver to read the control block (Metadata) stored in external memory

  - Checks for update in control block (Metadata)

  - Reads the application binary stored in external memory

  - Erases the Internal Flash memory

  - Programs the read binary into Flash memory

  - Verifies the programed application

  - Updates the control block (Metadata) in external memory

  - Jumps to the Application

  - Runs in Cooperative mode with other tasks in the system

OTA Bootloader With External Memory (For MPUs)

- AT91Bootstrap loads MPU OTA bootloader from SD Card/NAND/Serial Flash memory to DDR memory and executes it

- MPU OTA Bootloader Task:

  - Reads the metadata (image size) stored in the external memory

  - Reads the OTA application binary stored from the external memory and Programs the binary to the DDR memory

  - Jumps to the OTA application

  - Runs in Cooperative mode with other tasks in the system

Rev: G