1.5.3 Serial Memory Bootloader Configurations

Bootloader Specific User Configurations

  • Bootloader Serial Memory Used:

    • Specifies the Serial memory driver used by bootloader to receive the application
    • The name of the serial memory will vary based on the driver connected to bootloader

  • Bootloader NVM Memory Used:

    • Specifies the memory peripheral used by bootloader to perform Flash operations
    • The name of the peripheral will vary from device to device

  • Bootloader Size (Bytes):

    • Specifies the maximum size of Flash required by the bootloader
    • This size is calculated based on Bootloader type and Memory used
    • This size will vary from device to device and should always be aligned to device erase unit size

  • Enable Bootloader Trigger From Firmware:

    • This Option can be used to Force Trigger bootloader from application firmware after a soft reset. It does so by reserving the specified number of bytes in SRAM from the start of the RAM. The reserved memory is updated by the application with a pre-defined pattern. The bootloader firmware in the bootloader_Trigger() routine, can check the reserved memory for the pre-defined pattern and enter Bootloader mode if the pattern matches.

    • Number Of Bytes To Reserve From Start Of RAM:

      • This option adds the provided offset to RAM Start address in bootloader linker script
      • Application firmware can store some pattern in the reserved bytes region from RAM start for bootloader to check at reset in bootloader_Trigger() function

Bootloader System Configurations

  • Application Start Address (Hex):
    • Start address of the application which will programmed by bootloader
    • This value is filled by bootloader when its loaded which is equal to the bootloader size. It can be modified as per user need.
    • This value will be used by bootloader to jump to application at device reset

Bootloader MPLAB X Settings

  • As the Serial memory may not have any valid binary required by bootloader for the first time. Adding the application to be bootloaded as loadable allows MPLAB X to create a unified hex file and program both these applications in their respective memory locations.
    • By doing this, at first bootup bootloader directly jumps to application as the serial memory does not have any valid binary