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Issue regarding difference between bytes coping on flash memory of LPC1767

Question asked by Muhammad Bilal on Jul 17, 2019
Latest reply on Sep 11, 2019 by Muhammad Bilal

I have task to develop a software for writing hex content to flash, of course there are tools for it but the tools had issues so i had to make my own software for it but first i need to understand it (for understanding purpose i am using flashmagic software for now).

The issue is that its says in NXP LPCxx document that The length of any
UU-encoded line should not exceed 61 characters (bytes) i.e. it can hold 45 data bytes.
The receiver should compare it with the check-sum of the received bytes.

  1. My first question is that it is not mentioned in document or i am having understanding issue that will the after writing data in reader will the checksum will be send along it or after it separately.
  2. My second question is it says in document that 20 UU encoded lines are sent so basically does it mean 20 X 61 = 1220 bytes or 45 X 20 = 900 bytes? and is that 1 byte is for checksum?
  3. What is formula to calculate checksum?
  4. My third question is that i used flashmagic tool for now if 1220 bytes per cycle are sent to reader as mentioned in question 2, but the the amount of bytes that are copied from RAM to flash are 1024 bytes per cycle that are less than 1220 bytes or 900 bytes are the valid case. How is this possible that number of bytes that are copied to flash are less than 1220 byes.

Thanks in advance,