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