lock bits verus fuses

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A colleague has informed me that after changing lock bits on an atmega2560,

he can no longer change the fuses with jtag?

Is that right?

Did I miss something in the documentation?

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"Demons after money.
Whatever happened to the still beating heart of a virgin?
No one has any standards anymore." -- Giles

Last Edited: Tue. Sep 25, 2018 - 05:04 PM
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Found the documentation.

LB1 and LB2 can disable serial and parallel programming.

I suppose JTAG is lumped with serial.

"Demons after money.
Whatever happened to the still beating heart of a virgin?
No one has any standards anymore." -- Giles

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skeeve wrote:

LB1 and LB2 can disable serial and parallel programming.

 

LB1 and LB2 does not disable the programming interfaces. It restricts them to only be able to erase the entire chip.

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angelu wrote:
LB1 and LB2 does not disable the programming interfaces. It restricts them to only be able to erase the entire chip.
Well, not really.  It restricts them from being able to write flash, EEPROM, and fuses.  Read of flash and EEPROM can also be restricted.  Reading of fuses, signature, etc can always be performed.

 

In fact, read/write are still accepted, but write of write-protected memory has no effect and read of read-protected memory will return 0xFF.

 

You can still write lock bits that have not yet been written.

 

And chip erase ;-)

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Last Edited: Mon. Oct 1, 2018 - 03:22 AM