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2552K–AVR–04/11
ATmega329/3290/649/6490
9.8.2
PRR – Power Reduction Register
Bits 7, 6, 5 - Reserved bits
These bits are reserved bits in ATmega329/3290/649/6490 and will always read as zero.
Bit 4 - PRLCD: Power Reduction LCD
Writing logic one to this bit shuts down the LCD controller. The LCD controller must be disabled
and the display discharged before shut down. See "Disabling the LCD" on page 217 for details
on how to disable the LCD controller.
Bit 3 - PRTIM1: Power Reduction Timer/Counter1
Writing logic one to this bit shuts down the Timer/Counter1 module. When Timer/Counter1 is
enabled, operation will continue like before the shutdown.
Bit 2 - PRSPI: Power Reduction Serial Peripheral Interface
Writing logic one to this bit shuts down the Serial Peripheral Interface by stopping the clock to
the module. When waking up the SPI again, the SPI should be re-initialized to ensure proper
operation.
Bit 1 - PRUSART: Power Reduction USART
Writing logic one to this bit shuts down the USART by stopping the clock to the module. When
waking up the USART again, the USART should be re-initialized to ensure proper operation.
Bit 0 - PRADC: Power Reduction ADC
Writing logic one to this bit shuts down the ADC. The ADC must be disabled before shut down.
The analog comparator cannot use the ADC input MUX when the ADC is shut down.
Note:
Bit
7
6
5
4
3
210
–
PRLCD
PRTIM1
PRSPI
PRUSART0
PRADC
PRR
Read/Write
R
R/W
Initial Value
0