How to make sure that checksum is the same after changing program for EPROM?

[greatindia]

eprom checksum

How to make sure that the checksum of the program is same even when the program is changed for an EPROM.

Any way to cr@ck it?

-GreatIndia

 

[crono]

checksum eprom

If you need a safe check use a crc algorytm to test Your eprom.

I use this metod in a 8 bit microcontroller system:

1) reserve 2 byte for a pointer with the linker at a known address.

2) Compile and link the sw normally.

3) With a (dos !!) program I insert the address of the first byte after the end of file (take in account the eventually offset) in the reserved bytes. Then do the crc (16 or 32 bit) calculation of the file. Then append the crc result to the end of file and save the new file.

4) at every boot a crc routine check the crc till the end of file (&pointer - 1) and compare with result (*pointer)

Hope this can be useful.

_________________
Regards

crono


<font size=-1>[ This Message was edited by: crono on 2002-04-18 23:29 ]</font>

 

[__JR__]

safe eeprom checksum

Hi GreatIndia,

I'm not sure if I understand your question, but the checksum will remain the same if you fill the empty space in the EPROM with "00" (not "FF"). Then you can change EPROM size and/or manufacturer and the checksum will remain the same.
I hope that was your point...

Regards.

 

[jetmarc]

eprom checksum

Any way to cr@ck it?

If you can't make a valid checksum, you can still patch the verification function!

jetmarc