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6 Bootload Communication Protocol: 8-bit
6.9 Calculate Checksum

Enables the bootloader to calculate and return a checksum value over a given range of memory addresses.

1 MCC Melody Bootloader: 8-bit
2 User Interface
3 Unified Bootloader Host Application (UBHA)
4 Use Case Examples
5 Verification Schemes
This section discusses various methods to verify the application provided to the users by the bootloader module.
6 Bootload Communication Protocol: 8-bit
- 6.1 Read Version
  
  Enables the bootloader to read the version information from the configuration bits of the device.
- 6.2 Read Flash
  
  Enables the bootloader to interface with various memory drivers used by 8-bit PIC and 8-bit AVR chips.
- 6.3 Write Flash
  
  Enables the bootloader to write data to specified address locations.
- 6.4 Erase Flash
  
  Enables the bootloader to initiate erase commands to the memory driver.
- 6.5 Read EE Data
  
  Enables the bootloader to read bytes out from the EEPROM memory.
- 6.6 Write EE Data
  
  Enables the bootloader to write some number of bytes to the EEPROM memory.
- 6.7 Read Config
  
  Enables the bootloader to read the Configuration Words out of the chip’s memory.
- 6.8 Write Config
  
  Enables the bootloader to write to the Configuration Word range of memory.
- 6.9 Calculate Checksum
  
  Enables the bootloader to calculate and return a checksum value over a given range of memory addresses.
- 6.10 Reset Device
  
  Enables the bootloader to initiate the device’s software Reset cycle.
7 References
Microchip Information

6.9 Calculate Checksum

Enables the bootloader to calculate and return a checksum value over a given range of memory addresses.

Summary

There are several reasons for performing a checksum command on a given rage of memory, the most important one being for verification of the data writing operations in the bootloader. It is recommended for the host program to calculate an independent checksum as the hex file is programmed to the device. This precalculated value can later be compared to the checksums calculated on the device memory and either verify or reject the application data present on the chip before running it.