31
8331B–AVR–03/12
Atmel AVR XMEGA AU
4.16
Register Descriptions – Fuses and Lock bits
4.16.1
FUSEBYTE0 – Fuse Byte 0
• Bit 7 – JTAGUID[7:0]: JTAG USER ID
These fuses can be used to set the default JTAG user ID for the device. During reset, the
JTAGUID fuse bits will be loaded into the MCU JTAG user ID register.
4.16.2
FUSEBYTE1 – Fuse Byte1
• Bit 7:4 – WDWPER[3:0]: Watchdog Window Timeout Period
These fuse bits are used to set initial value of the closed window for the Watchdog Timer in Win-
dow Mode. During reset these fuse bits are automatically written to the WPER bits Watchdog
Window Mode Control Register. Refer to
”WINCTRL – Window Mode Control register” on page
for details.
• Bit 3:0 – WDPER[3:0]: Watchdog Timeout Period
These fuse bits are used to set the initial value of the watchdog timeout period. During reset
these fuse bits are automatically written to the PER bits in the watchdog control register. Refer to
”CTRL – Control register” on page 130
for details.
4.16.3
FUSEBYTE2 – Fuse Byte2
• Bit 7 – Reserved
This bit is unused and reserved for future use. For compatibility with future devices, always write
this bit to one when this register is written.
Bit
7
6
5
4
3
2
1
0
+0x00
JTAGUID[7:0]
FUSEBYTE0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
1
1
1
1
1
1
1
1
Bit
7
6
5
4
3
2
1
0
+0x01
WDWPER[3:0]
WDPER[3:0]
FUSEBYTE1
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
0
0
0
0
0
0
0
0
Bit
7
6
5
4
3
2
1
0
+0x02
–
BOOTRST
TOSCSEL
–
–
–
BODPD[1:0]
FUSEBYTE2
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Initial Value
1
1
1
1
1
1
1
1
