Datasheet

337
7682C–AUTO–04/08
AT90CAN32/64/128
Notes: 1. The SPIEN Fuse is not accessible in serial programming mode.
2. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 24-6 on page 333
for details.
3. See “Watchdog Timer Control Register – WDTCR” on page 57 for details.
4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of Lock bits
and JTAGEN Fuse. A programmed OCDEN Fuse enables some parts of the clock system to
be running in all sleep modes. This may increase the power consumption.
5. If the JTAG interface is left unconnected, the JTAGEN fuse should if possible be disabled. This
to avoid static current at the TDO pin in the JTAG interface.
6. The boot sizes of all the AVR CAN microcontrollers are identical.
7. Due to the flash size, the boot reset address differs from one AVR CAN microcontroller to
another.
Notes: 1. The default value of SUT1..0 results in maximum start-up time for the default clock source.
See
Table 5-8 on page 42 for details.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz. See Table 5-1 on
page 38 for details.
3. The CKOUT Fuse allow the system clock to be output on Port PC7. See “Clock Output Buffer”
on page 43 for details.
4. See “System Clock Prescaler” on page 44 for details.
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if
Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.
25.2.1 Latching of Fuses
The fuse values are latched when the device enters programming mode and changes of the
fuse values will have no effect until the part leaves Programming mode. This does not apply to
the EESAVE Fuse which will take effect once it is programmed. The fuses are also latched on
Power-up in Normal mode.
BOOTSZ1 2
Select Boot Size
(6)
(see Table 24-6 for details)
0 (programmed)
(2)
BOOTSZ0 1
Select Boot Size
(6)
(see Table 24-6 for details)
0 (programmed)
(2)
BOOTRST 0
Select Reset Vector
(7)
(see
Table 24-6 for details)
1 (unprogrammed)
Table 25-5. Fuse Low Byte
Fuse Low Byte Bit No Description Default Value
CKDIV8
(4)
7 Divide clock by 8 0 (programmed)
CKOUT
(3)
6 Clock output 1 (unprogrammed)
SUT1 5 Select start-up time 1 (unprogrammed)
(1)
SUT0 4 Select start-up time 0 (programmed)
(1)
CKSEL3 3 Select Clock source 0 (programmed)
(2)
CKSEL2 2 Select Clock source 0 (programmed)
(2)
CKSEL1 1 Select Clock source 1 (unprogrammed)
(2)
CKSEL0 0 Select Clock source 0 (programmed)
(2)
Table 25-4. Fuse High Byte (Continued)
Fuse High Byte Bit No Description Default Value