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42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
transceiver. The SRAM is shut down by a DRT switch and the radio transceiver is in
reset state if its respective power reduction bit is set.
Module shutdown can be used in Idle mode and Active mode to significantly reduce the
examples. In all other sleep modes, the clock is already stopped.
12.4 Minimizing Power Consumption
There are several issues to consider when trying minimizing the power consumption in
an AVR controlled system. In general, sleep modes should be used as much as
possible, and the sleep mode should be selected so that as few as possible of the
device’s functions are operating. All functions not needed should be disabled. In
particular, the following modules may need special consideration when trying to achieve
the lowest possible power consumption.
12.4.1 Analog to Digital Converter
If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should
12.4.2 Analog Comparator
When entering Idle mode, the Analog Comparator should be disabled if not used. When
entering ADC Noise Reduction mode the Analog Comparator should also be disabled.
In other sleep modes, the Analog Comparator is automatically disabled. However, if the
Analog Comparator is set up to use the Internal Voltage Reference as input, the Analog
Comparator should be disabled in all sleep modes. Otherwise, the Internal Voltage
Reference will be enabled, independent of sleep mode. Refer to
"AC – Analog12.4.3 Brown-out Detector
If the Brown-out Detector is enabled by the BODLEVEL Fuses, it will be disabled in
configure the Brown-out Detector. It is recommended to enable the Brown-out Detector.
12.4.4 Internal Voltage Reference
The Internal Voltage Reference will be enabled when needed by the Brown-out
Detection, the Analog Comparator or the ADC. If these modules are disabled as
described in the sections above, the internal voltage reference will be disabled and not
consume power. When turned on again, the user must allow the reference to start up
before the output is used. If the reference is kept on in sleep mode, the output can be
start-up time.
12.4.5 Watchdog Timer
If the Watchdog Timer is not needed in the application, the module should be turned off.
If the Watchdog Timer is enabled, it will be enabled in all sleep modes, and hence,
always consume power. In the deeper sleep modes, this will contribute significantly to
how to configure the Watchdog Timer.