'How can I calculate checksum of code protected PIC'
Can someone explain the SUM_XNOR7 method?
I have read capter 4.3 in the "EEPROM Memory Programming Specification" documentation,
but I don't understand it...
What does the text in the upper right cell mean? (0x25E6 at 0 and max address)
I have tried to calculate theire example but I don't get the right answer.
location_a = 0x123 = 00 0001 0010 0011
location_b = 0x456 = 00 0100 0101 0110
SUM_XNOR7[location_a:location_b] = 0x001F How?!?!?!
XNOR of location_a:
upper 7 bits: 0000010
lower 7 bits: 0100011
XNOR of location_b:
upper 7 bits: 0001000
lower 7 bits: 1010110
1011110 + 0100001 = 0x007F But it suppose to be 0x001F..?!?!?
Please help me, I am writing a PIC programmer for Win 95/98/NT
and I would like to implement errorchecking for code protected chips.
Is that possible??
>Sender: pic microcontroller discussion list <MITVMA.MIT.EDU> PICLIST
>From: Tomas Franzon <STUDENT.LIU.SE> tomfr343
>Subject: How can I calculate checksum of code protected PIC16C84?
>Can someone explain the SUM_XNOR7 method?
>I have read capter 4.3 in the "EEPROM Memory Programming Specification"
>but I don't understand it...
>What does the text in the upper right cell mean? (0x25E6 at 0 and max
to test your function, fill 0x25E6 at address 0 and max, then compare your
I think it should be 0xFF7F
use this function:
for (i=start; i<end; i++)
high = (TempWord[i] >> 7) & 0x007F;
low = TempWord[i] & 0x007F;
hml = ~(high ^ low);
SUM += hml;
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