lpcware

Cortex-M3 valid user code

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by reza_elc87 on Tue Jun 30 01:55:12 MST 2015
Dear all,
Hello!

I have developed a C# program that can send a .hex file to the flash memory of LPC1768 using ISP. But the program does not work well. I know the problem is that it cannot verify a valid user code, because the checksum at location 7 of the vector table is incorrect.
this is the first 8 entries of my vector table:

:10000000       68020010 69010000 71010000 73010000       26
:10001000       75010000 77010000 79010000 [color=#f06]00000000[/color]       78

I know instead of those red zeros I need to put the two's complement of the checksum. The only problrm is that I do not know how to calculate the checksum and its two's complement.
Flash magic calculates it and gives:
E6F4FFEF

BUT HOW???

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