ATMEGA32_14 Datasheet, PDF (34/346 Pages) ATMEL Corporation – High Endurance Non-volatile Memory segments

ATmega32(L)
Standby Mode
When the SM2..0 bits are 110 and an external crystal/resonator clock option is selected, the
SLEEP instruction makes the MCU enter Standby mode. This mode is identical to Power-down
with the exception that the Oscillator is kept running. From Standby mode, the device wakes up
in six clock cycles.
Extended Standby
Mode
When the SM2..0 bits are 111 and an external crystal/resonator clock option is selected, the
SLEEP instruction makes the MCU enter Extended Standby mode. This mode is identical to
Power-save mode with the exception that the Oscillator is kept running. From Extended Standby
mode, the device wakes up in six clock cycles..
Table 14. Active Clock Domains and Wake Up Sources in the Different Sleep Modes
Active Clock domains Oscillators
Wake-up Sources
Sleep Mode
Idle
XX X
X
X⁽²⁾
X
X X XXX
ADC Noise
Reduction
XX
X
X⁽²⁾
X⁽³⁾
X
X
XX
Power-down
X⁽³⁾
X
Power-save
X⁽²⁾
X⁽²⁾
X⁽³⁾
X
X⁽²⁾
Standby⁽¹⁾
X
X⁽³⁾
X
Extended
Standby⁽¹⁾
X⁽²⁾ X
X⁽²⁾
X⁽³⁾
X
X⁽²⁾
Notes: 1. External Crystal or resonator selected as clock source.
2. If AS2 bit in ASSR is set.
3. Only INT2 or level interrupt INT1 and INT0.
Minimizing Power
Consumption
There are several issues to consider when trying to minimize 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.
Analog to Digital
Converter
If enabled, the ADC will be enabled in all sleep modes. To save power, the ADC should be dis-
abled before entering any sleep mode. When the ADC is turned off and on again, the next
conversion will be an extended conversion. Refer to “Analog to Digital Converter” on page 201
for details on ADC operation.
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2503Q–AVR–02/11