I am trying to figure out how ATECC608A handles the CRC. I do not have yet datasheet for ATECC608A-SSHDA, I do have for ATECC508A and ATECC608A-TNGTLS. Both these two datasheets describe the same functionality regarding CRC.
I started to test with the simplest command, Info. For start, I built the I2C packet and for CRC I did calculated with online calculator just to test. It did not work. Out of solution, I made a loop and tested all 65536 possible values. After about 21 minutes I got a match. However, I cant' get any online calculators to get the same value. When the CRC is correct, it replies with data requested. Here is what it works:
receive from ATECC608A - last two bytes are CRC
I did try online calculators:
What could be the problem ?