
195
42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
These bits select between the five available sleep modes. Standby modes are only
recommended for use with external crystals or resonators.
Table 12-103 SM Register Bits
Register Bits
Value
Description
SM2:0
0x00
Idle
0x01
ADC Noise Reduction (If Available)
0x02
Power Down
0x03
Power Save
0x04
Reserved
0x05
Reserved
0x06
Standby
0x07
Extended Standby
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 executed. To avoid the MCU entering the sleep mode unless it
is the programmers 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.
12.6.2 PRR0 – Power Reduction Register0
Bit
7
6
5
4
3
2
1
0
NA ($64)
PRTWI
PRTIM2
PRTIM0
PRPGA
PRTIM1
PRSPI
PRUSART0
PRADC
PRR0
Read/Write
R/W
Initial Value
0
Bit 7 – PRTWI - Power Reduction TWI
Writing a logic one to this bit shuts down the TWI by stopping the clock to the module.
When waking up the TWI again, the TWI should be re initialized to ensure proper
operation.
Bit 6 – PRTIM2 - Power Reduction Timer/Counter2
Writing a logic one to this bit shuts down the Timer/Counter2 module. When the
Timer/Counter2 is enabled, operation will continue like before the shutdown.
Bit 5 – PRTIM0 - Power Reduction Timer/Counter0
Writing a logic one to this bit shuts down the Timer/Counter0 module. When the
Timer/Counter0 is enabled, operation will continue like before the shutdown.
Bit 4 – PRPGA - Power Reduction PGA
Writing a logic one to this bit reduced the power consumption of the programmable gain
amplifier. The block is not turned off. Only the current levels in the amplifiers are
reduced. Reducing the PGA current levels is only recommended for slow ADC clock
frequencies. A new ADC conversion using the PGA should be delayed by a default
start-up time after changing (setting or resetting) this bit.
Bit 3 – PRTIM1 - Power Reduction Timer/Counter1
Writing a logic one to this bit shuts down the Timer/Counter1 module. When the
Timer/Counter1 is enabled, operation will continue like before the shutdown.