NXP LPC2xxx valid user code
Some MCUs (e.g. LPC2xxx family) designed by NXP Semiconductors expect a checksum of the interrupt vectors to validate the user code. If the checksum matches the user code will be executed as expected, otherwise the code will not be executed.
The interrupt vector at 0x0000_0014 should contain the Two's complement of the sum of the other interrupt vectors.
Example content of interrupt vectors:
Sum (32 bit unsigned integer) of all interrupt vectors (despite 0x0000_0014):
Sum = 0x6BFFFFFA
Checksum (32 bit unsigned integer) at 0x0000_0014 (two's complement of sum):
Checksum = ~(Sum) + 1 = 0x94000006
J-Flash will display a pop-up if the checksum is not valid and will offer to calculate the correct checksum for the user code:
If you do not want that the pop-up will show up, make sure that the checksum is correctly calculated in your data-file (see Calculation).