Write only a part of the flash

I am trying to flash the MCU storage only partially. As there does not seem to be any function that allows flashing at a certain address, I tried to use a hex file. The hex file has one section of 0x800 bytes starting at 0x4000. The file is flashed ok and I can read the correct data back.

I am facing a problem tough, it seems that the flash memory up to the hex starting address gets corrupted.

Any suggestions would help. Thank you.

Start by reproducing the reported HEX-file flash with one 0x800-byte section at address 0x4000, then compare the preceding flash region before and after programming. Done means the section is written correctly without corrupting flash below its starting address.

Written by the indexing model from the issue text.