
221
4378C–AVR–09/08
AT90PWM1
22.2
Fuse Bits
The AT90PWM1 has three Fuse bytes.
Table 76 -
Table 78 describe briefly the functionality of
all the fuses and how they are mapped into the Fuse bytes. Note that the fuses are read as logi-
cal zero, “0”, if they are programmed.
Note:
for details.
22.3
PSC Output Behaviour During Reset
For external component safety reason, the state of PSC outputs during Reset can be pro-
grammed by fuses PSCRV, PSC0RB, PSC1RB & PSC2RB.
These fuses are located in the Extended Fuse Byte ( see
Table 76)PSCRV gives the state low or high which will be forced on PSC outputs selected by PSC0RB,
PSC2RB fuses.
If PSCRV fuse equals 0 (programmed), the selected PSC outputs will be forced to low state. If
PSCRV fuse equals 1 (unprogrammed), the selected PSC outputs will be forced to high state.
If PSC0RB fuse equals 1 (unprogrammed), PSCOUT00 & PSCOUT01 keep a standard port
behaviour. If PSC0RB fuse equals 0 (programmed), PSCOUT00 & PSCOUT01 are forced at
reset to low level or high level according to PSCRV fuse bit. In this second case, PSCOUT00 &
PSCOUT01 keep the forced state until PSOC0 register is written..
If PSC2RB fuse equals 1 (unprogrammed), PSCOUT20, PSCOUT21, PSCOUT22 &
PSCOUT23 keep a standard port behaviour. If PSC1RB fuse equals 0 (programmed),
PSCOUT20, PSCOUT21, PSCOUT22 & PSCOUT23 are forced at reset to low level or high
level according to PSCRV fuse bit. In this second case, PSCOUT20, PSCOUT21, PSCOUT22 &
PSCOUT23 keep the forced state until PSOC2 register is written.
Table 76. Extended Fuse Byte
Extended Fuse Byte
Bit No
Description
Default Value
PSC2RB
7
PSC2 Reset Behaviour
1
PSC0RB
5
PSC0 Reset Behaviour
1
PSCRV
4
PSCOUT Reset Value
1
–3
–
1
BOOTSZ1
2
Select Boot Size
(see Table 113 for details)
0 (programmed)
BOOTSZ0
1
Select Boot Size
(see Table 113 for details)
0 (programmed)
BOOTRST
0
Select Reset Vector
1 (unprogrammed)