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42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
12 Power Management and Sleep Modes
Sleep modes enable the application to shut down unused modules in the MCU, thereby
saving power. The AVR microcontroller and the RF transceiver provide various sleep
modes allowing the user to tailor the power consumption to the application’s
requirements.
12.1 Deep-Sleep Mode
When the microcontroller goes into Power-down or Power-save modes while the
transceiver is in SLEEP state the device enters the Deep-Sleep mode.
Sending the microcontroller to Power-down or Power-save is not allowed during the
wake-up phase of the transceiver. The TRX24_AWAKE interrupt shall be used to wait
for the transceiver is operational.
The DVDD voltage regulator and the associated power chain will be switched off.
Remaining running logic will then be supplied from the Low Leakage Voltage Regulator.
188 how to disable the radio transceiver.
Before entering Deep-Sleep mode the automatic calibration of the Low Leakage
Voltage Regulator must be completed. This automatic calibration can be temporarily
The SRAM blocks use the data retention mode to preserve its content while saving
leakage power. The Low Leakage Voltage Regulator has only limited driving
Therefore the remaining running logic must be clocked with low frequencies only.
The Deep-Sleep mode can be finished by a wake-up source shown by the
Table 12-1on page 184. Then DVDD voltage regulator and the associated power chain will be
switched on. If the power-chain is completely enabled the standard AVR wake-up
Note that the wake-up time from Deep-sleep mode is significantly longer than the wake-
up time from the Power-down or Power-save mode because the entire power-chain will
be restarted.
Additionally note that if the ADC is enabled and/or running a conversion, while entering
Deep-sleep mode, the ADC supply voltage is switched off. Therefore the ADC must be
disabled before entering Deep-sleep mode to avoid an undefined ADC operation.
If Timer/Counter 2 is not operated asynchronously (i.e., AS2 in ASSR is 0), the timer is
implies the main oscillator (as selected by the fuse configuration) is kept running. The
power chain remains enabled and the device does not enter the Deep-Sleep mode.
Assembly Code Example
…
ldi
r16, (1<<SLPTR)
sts
TRXPR, r16
; disable transceiver
ldi
r16, (2<<SM0) + (1<<SE)
; select power down mode
out
SMCR, r16
; enable sleep mode
sleep
; go to deep sleep
…