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ATtiny40 [DATASHEET]
8263B–AVR–01/2013
Bit 0 – SE: Sleep Enable
The SE bit must be written to logic one to make the MCU enter the sleep mode when the SLEEP instruction is exe-
cuted. To avoid the MCU entering the sleep mode unless it is the programmer’s purpose, it is recommended to
write the Sleep Enable (SE) bit to one just before the execution of the SLEEP instruction and to clear it immediately
after waking up.
7.5.2
PRR – Power Reduction Register
Bits 7:5 – Res: Reserved Bits
These bits are reserved and will always read as zero.
Bit 4 – PRTWI: Power Reduction Two-Wire Interface
Writing a logic one to this bit shuts down the Two-Wire Interface module.
Bit 3 – PRSPI: Power Reduction Serial Peripheral Interface
Writing a logic one to this bit shuts down the Serial Peripheral Interface module.
Bit 2 – PRTIM1: Power Reduction Timer/Counter1
Writing a logic one to this bit shuts down the Timer/Counter1 module. When the Timer/Counter1 is enabled, opera-
tion will continue like before the shutdown.
Bit 1 – PRTIM0: Power Reduction Timer/Counter0
Writing a logic one to this bit shuts down the Timer/Counter0 module. When the Timer/Counter0 is enabled, opera-
tion will continue like before the shutdown.
Bit 0 – PRADC: Power Reduction ADC
Writing a logic one to this bit shuts down the ADC. The ADC must be disabled before shut down. The analog com-
parator cannot use the ADC input MUX when the ADC is shut down.
Table 7-2.
Sleep Mode Select
SM2
SM1
SM0
Sleep Mode
000
Idle
0
1
ADC noise reduction
010
Power-down
011
Reserved
100
Standby
101
Reserved
110
Reserved
111
Reserved
Bit
7
6
5
4
3
2
1
0
–
PRTWI
PRSPI
PRTIM1
PRTIM0
PRADC
PRR
Read/Write
R
R/W
Initial Value
0