1.4.1 Configuring an application to be bootloaded for CORTEX-M based MCUs

Application settings in MCC system configuration

  1. Launch MCC for the application project to be configured

  2. Select system component from the project graph and configure the below highlighted settings

    application_config_mhc_setting

  3. Disable Fuse Settings:

    • Fuse settings needs to be disabled for the application which will be boot-loaded as the fuse settings are supposed to be programmed through programming tool from bootloader code. Also the fuse settings are not programmable through firmware

    • Enabling the fuse settings also increases the size of the binary when generated through the hex file

    • When updating the bootloader itself, make sure that the fuse settings for the bootloader application are also disabled

  4. Specify the Application Start Address:

    • Specify the Start address from where the application will run under the Application Start Address (Hex) option in System block in MCC.

    • This value should be equal to or greater than the bootloader size and must be aligned to the erase unit size on that device.

    • As this value will be used by bootloader to Jump to application at device reset it should match the value provided to bootloader code

    • The Application Start Address (Hex) will be used to generate XC32 compiler settings to place the code at intended address

    • After the project is regenerated, the ROM_ORIGIN and ROM_LENGTH are the XC32 linker variables which will be overridden with value provided for Application Start Address (Hex) and can be verified under Options for xc32-ld in Project Properties in MPLABX IDE as shown below.

    application_config_xc32_ld_rom

MPLAB X Settings

  • Specifying post build option to automatically generate the binary file from hex file once the build is complete

    • The generated binary file can directly be copied on to the SD card when using host_app_sdcard host application

    • The generated binary file will serve as an input to the btl_bin_to_c_array.py to generate a C style array containing HEX data when the host_app_nvm host application is used

    ${MP_CC_DIR}/xc32-objcopy -I ihex -O binary ${DISTDIR}/${PROJECTNAME}.${IMAGE_TYPE}.hex ${DISTDIR}/${PROJECTNAME}.${IMAGE_TYPE}.bin

    application_config_post_build_script

Additional settings (Optional)

  • RAM_ORIGIN and RAM_LENGTH values should be provided for reserving configured bytes from start of RAM to trigger bootloader from firmware

  • Under Project Properties, expand options for xc32-ld and define the values for RAM_ORIGIN and RAM_LENGTH under Additional options

  • This is optional and can be ignored if not required

application_config_xc32_ld_ram