1.4.3 CAN Bootloader Configurations

Bootloader Specific User Configurations

For devices with Dual Bank support and No Data Cache:

For devices with No Dual Bank support and Data Cache:

  • Bootloader Peripheral Used:

    • Specifies the communication peripheral used by bootloader to receive the application
    • The name of the peripheral will vary from device to device

  • 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

  • Use Dual Bank for Safe Flash Update:

    • Used to configure bootloader to use Dual banks of device to upload the application
    • This option is visible only for devices supporting Dual Flash banks

  • Select MPU Region to Configure Non-cacheable Memory:

    • Used to select the MPU region for which he SRAM has been configured as non-cahceable space

    • Configure the region selected above in MPU settings of MCC as shown in Bootloader MPU Configurations

    • A separate section will be created for this region in the custom linker script generated for bootloader

    • This option is visible only for devices which have Data cache

Bootloader Memory Protection Unit (MPU) Configurations

  • Open MPU settings from MCC>Tools option. Select Enable MPU.

  • Configure the region selected in Bootloader component as ram_nocache with other parameters as shown:

Bootloader Linker code for ram_nochache.

  • For CAN bootloader below xxx_message_ram section will be added to the custom linker file generated:
    • Note: xxx should be replaced with the CAN PLIB being used.
    • Example: MCAN1
    MEMORY
{
  rom (rx) : ORIGIN = ROM_START, LENGTH = ROM_SIZE
  ram (rwx) : ORIGIN = RAM_START, LENGTH = RAM_SIZE

  /* The address mentioned here should match with address mentioned in MPU settings */
  ram_nocache (RWX) : ORIGIN = 0x2045f000, LENGTH = (1 << (11 + 1))

}

...
...

.mcan1_message_ram (NOLOAD):
{
    . = ALIGN(4);
    _s_mcan1_message_ram = .;
    *(.mcan1_message_ram)
    . = ALIGN(4);
    _e_mcan1_message_ram = .;
} > ram_nocache

...
  • CAN Bootloader will use this section to allocate MCAN Message RAM configuration in contiguous non-cacheable buffer
    static uint8_t CACHE_ALIGN __attribute__((space(data), section (".mcan1_message_ram"))) mcan1MessageRAM[MCAN1_MESSAGE_RAM_CONFIG_SIZE];

/* Set MCAN1 Message RAM Configuration */
MCAN1_MessageRAMConfigSet(mcan1MessageRAM);

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
Note:

  • For optimizing the code Bootloader component disables generation of default interrupt and exception files as shown below

  • Enabling these interrupts explicitly may still not work as bootloader uses custom startup file which has its own Interrupt table populating only the reset handler

For MPUs (Microprocessors):

Bootloader Specific User Configurations

Bootloader with SD/eMMC media

Bootloader with NAND Flash media

Bootloader with Serial Flash media

  • Bootloader Peripheral Used:

    • Specifies the communication peripheral used by bootloader to receive the application
    • The name of the peripheral will vary from device to device

  • Application Binary Image Path:

    • Application binary image name harmony.bin (by default)

  • Application Start Address (Hex):

    • Start address of the application on which bootloader will load and execute application
    • This value will be used by bootloader to load and jump to application at device reset

  • Bootloader Memory Used (For Serial/NAND Flash):

    • Specifies the Flash Driver used by bootloader to receive the application
    • The name of the Flash Driver will vary from device to device

  • External Memory App Image Address (Hex) (For Serial/NAND Flash):

    • External Memory App Image Address (0x00200000) on which bootloader will program the application image
    • This value will also be used by bootloader to load the application from external memory to the DDR memory and execute it

  • External Memory Metadata Address (Hex) (For Serial/NAND Flash):

    • External Memory Metadata Address (0x00180000) on which bootloader will program the size of application binary
    • This value will be used by bootloader to read the application image from external memory

MPLAB X Settings (For MPUs)

  • Specifying post build option to automatically generate the Harmony 3 bootloader binary file from ELF file once the build is complete
    ${MP_CC_DIR}/xc32-objcopy -Obinary ${ImageDir}/${ConfName}.X.${IMAGE_TYPE}.elf ${ImageDir}/harmony_bootloader.bin