Rainbow Electronics ATmega64C1 - Manual (Page 42)

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7647A–AVR–02/08
ATmega32/64/M1/C1
Writing a logic one to this bit reduces the consumption of the PSC by stopping the clock to this
module. When waking up the PSC again, the PSC should be re initialized to ensure proper
operation.
• Bit 4 - PRTIM1: Power Reduction Timer/Counter1
Writing a logic one to this bit reduces the consumption of the Timer/Counter1 module. When the
Timer/Counter1 is enabled, operation will continue like before the setting of this bit.
• Bit 3 - PRTIM0: Power Reduction Timer/Counter0
Writing a logic one to this bit reduces the consumption of the Timer/Counter0 module. When the
Timer/Counter0 is enabled, operation will continue like before the setting of this bit.
• Bit 2 - PRSPI: Power Reduction Serial Peripheral Interface
Writing a logic one to this bit reduces the consumption of the Serial Peripheral Interface by stop-
ping the clock to this module. When waking up the SPI again, the SPI should be re initialized to
ensure proper operation.
• Bit 1 - PRLIN: Power Reduction LIN
Writing a logic one to this bit reduces the consumption of the UART controller by stopping the
clock to this module. When waking up the UART controller again, the UART controller should be
re initialized to ensure proper operation.
• Bit 0 - PRADC: Power Reduction ADC
Writing a logic one to this bit reduces the consumption of the ADC by stopping the clock to this
module. The ADC must be disabled before using this function. The analog comparator cannot
use the ADC input MUX when the clock of ADC is stopped.
6.7 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.
6.7.1 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 - ADC” on page
227 for details on ADC operation.
6.7.2 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 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
“Analog Comparator” on page 258 for details on how to configure the Analog
Comparator.
6.7.3 Brown-out Detector
If the Brown-out Detector is not needed by the application, this module should be turned off. If
the Brown-out Detector is enabled by the BODLEVEL Fuses, it will be enabled in all sleep
modes, and hence, always consume power. In the deeper sleep modes, this will contribute sig-