Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

through a dedicated Peripheral Bus address. Some of the general-purpose fuse bits are
reserved for special purposes, and should not be used for other functions.:

The BOOTPROT fuses protects the following address space for the Boot Loader:

General-purpose fuses with special functions

15:0

LOCK

Region lock bits.

16

EPFL

External Privileged Fetch Lock. Used to prevent the CPU from 
fetching instructions from external memories when in privileged 
mode. This bit can only be changed when the security bit is 
cleared. The address range corresponding to external 
memories is device-specific, and not known to the flash 
controller. This fuse bit is simply routed out of the CPU or bus 
system, the flash controller does not treat this fuse in any 
special way, except that it can not be altered when the security 
bit is set.

If the security bit is set, only an external JTAG Chip Erase can 
clear EPFL. No internal commands can alter EPFL if the 
security bit is set.

When the fuse is erased (i.e. "1"), the CPU can execute 
instructions fetched from external memories. When the fuse is 
programmed (i.e. "0"), instructions can not be executed from 
external memories.

19:17

BOOTPROT

Used to select one of eight different bootloader sizes. Pages 
included in the bootloader area can not be erased or 
programmed except by a JTAG chip erase. BOOTPROT can 
only be changed when the security bit is cleared.

If the security bit is set, only an external JTAG Chip Erase can 
clear BOOTPROT, and thereby allow the pages protected by 
BOOTPROT to be programmed. No internal commands can 
alter BOOTPROT or the pages protected by BOOTPROT if the 
security bit is set.

Boot Loader area specified by BOOTPROT

7

None

0

6

0-1

1kByte

5

0-3

2kByte

4

0-7

4kByte

3

0-15

8kByte

2

0-31

16kByte

1

0-63

32kByte

0

0-127

64kByte