6.16. Checksum

The chksum module is part of the foxBMS-Modules layer.

This section describes the embedded part of the checksum feature in foxBMS. For the buildprocess documentation on the checksum feature, see Build Process.

The chksum module provides the capability to verify data integrity during runtime for multiple purposes (e.g., firmware validation and verification of sent/received data).

6.16.1. Module Files

Source:
  • embedded-software\mcu-common\src\driver\chksum\chksum.h (chksum.h)
  • embedded-software\mcu-common\src\driver\chksum\chksum.c (chksum.c)

6.16.2. Detailed Description

The chksum module offers 2 possibilities to check data integrity, Modulo32BitAddition and a hardware based, slightly modified CRC32 implementation. The following short examples demonstrate the usage of the chksum module:

uint32_t chksum = CHK_crc32((uint8_t*)0x08000000, 0x1000) -> hashes 4kB of
code, starting at 0x08000000 using CRC32 algorithm

uint32_t chksum = CHK_modulo32addition((uint8_t*)0x08000000, 0x1000) ->
hashes 4kB of code, starting at 0x08000000 using Modulo32BitAddition
algorithm

During the startup, the CHK_crc32 function is used to verify the integrity of the flashed firmware image. After the calculation of the CRC32 checksum, it is compared to a hardcoded value within the flashheader struct. When both values match, the firmware is valid and execution continues. If both values do not match, an error is reported.

The flashheader contains the validation and checksum information with memory areas of separate software partitions, it gets generated during compilation by an external checksum tool, written in python. Furthermore it also provides the possibility for software versioning.

6.16.3. Checksum Configuration

Enabling/disabling of the checksum verification at startup is set by the following macro:

// deactivating the chechsum
#define BUILD_MODULE_ENABLE_FLASHCHECKSUM           0

// activating the chechsum
#define BUILD_MODULE_ENABLE_FLASHCHECKSUM           1

6.16.4. Checksum Default Configuration

The default value enables checksum verification at startup.