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confused
Guest
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| security settings |
 Posted: Thu Apr 10, 2008 4:25 am |
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i have some a program that when it has run x times ( expires ) will delete itself. for this reason i have to have the ebtr fuses disabled and it records how many times it has run in the data eeprom ( its a 2680 ).
so i have to have the eeprom unprotected as well.
what would you recommend security wise to protect the program from being read out.
as i find the security settings for this device very confusing, and the documentation is a bit specialist for me. |
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Dimmu
Joined: 01 Jul 2007
Posts: 37
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| Posted: Thu Apr 10, 2008 4:55 am |
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Which type of CPU do you use ?
Is it able to write its own memory ?
Dimmu |
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Guest
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| Posted: Thu Apr 10, 2008 5:09 am |
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| yes its a 18f2680 |
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Matro
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| Posted: Thu Apr 10, 2008 6:10 am |
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Have a look et page 348 of the datasheet.
There are fuses for code protection.
Matro. |
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Matro
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| Posted: Thu Apr 10, 2008 6:12 am |
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And complete explanations on page 358.
T think that's what you need.
Matro. |
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Guest
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| Posted: Thu Apr 10, 2008 6:51 am |
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yes thats my problem, ( did anyone actually read my original post)
what i am concerned with, is things like extra code being burnt into memory
that will then use table reads/writes to fetch out the remaining code.
should i enable/disable LVP, the whole thing is quite confusing.
my icd2 requires all secuirity to be turned off, the program works well
on the icd2, but when i turn on the security settings, i have no way of checking everything works properly, i have found that wrtd stops the thing from working.
and i wondered if anyone had a tried and tested setup to do what i have
detailed. or at least suggestions. |
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Matro
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| Posted: Thu Apr 10, 2008 7:33 am |
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| Anonymous wrote: | yes thats my problem, ( did anyone actually read my original post)
what i am concerned with, is things like extra code being burnt into memory
that will then use table reads/writes to fetch out the remaining code.
should i enable/disable LVP, the whole thing is quite confusing.
my icd2 requires all secuirity to be turned off, the program works well
on the icd2, but when i turn on the security settings, i have no way of checking everything works properly, i have found that wrtd stops the thing from working.
and i wondered if anyone had a tried and tested setup to do what i have
detailed. or at least suggestions. |
I really don't understand the problem.
Of course a code protection will block icd2 debugging.
What is the problem if you set all CP fuses?
No extra code can be written, and your program memory and EEPROM can't be read and write externally but it is possible internally.
Why is this solution not appropriate?
Matro. |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Thu Apr 10, 2008 8:09 am |
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| Quote: | | should i enable/disable LVP, the whole thing is quite confusing. |
Low Voltage Programming (LVP) has nothing to do with protection. It is another method to program the CPU but has some limitations and at most 1% of the people are using it. An ICD2 uses High Voltage Programming. Always set the fuse to NOLVP, this will free an I/O pin and prevents problems when by accident the LVP pin is made active. |
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