When to Set the Lockbits using Atmel Studio

Thehon1985 · Joined: 20 Feb 2007 Posts: 8

I use Atmel Studio to burn my programs to my chips. I want to have it so no one can program or verify the chips after I burn them. Do I burn the program and then set the lockbits?

Also, if I make a mistake and want to re-use the chip after setting the lockbit to not allow further programming, what can I do?

Matt

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

Burn the program first, then the fuse bits, then the lock bits last, maybe even after you have tested to make sure the device is functional.

The lock bits only disable reading and writing the program, depending which bits are set. They do not prevent you from doing a chip erase.
That will clear both the lock bits and the program, so you get back to a blank chip.

Be aware that it is possible to disable both the JTAG and the ISP programming interfaces by setting the relevant fuse bits. Once you do this, you can only recover with a parallel connection and high voltage programmer.