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 seperate 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 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 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