Rainbow-electronics ATmega64C1 Manuel d'utilisateur télécharger pdf (Page 41)

7647A–AVR–02/08

ATmega32/64/M1/C1

with the exception that the Oscillator is kept running. From Standby mode, the device wakes up

in six clock cycles.

Notes: 1. Only recommended with external crystal or resonator selected as clock source.

2. Only level interrupt.

6.6 Power Reduction Register

The Power Reduction Register, PRR, provides a method to stop the clock to individual peripher-

als to reduce power consumption. The current state of the peripheral is frozen and the I/O

registers can not be read or written. Resources used by the peripheral when stopping the clock

will remain occupied, hence the peripheral should in most cases be disabled before stopping the

clock. Waking up a module, which is done by clearing the bit in PRR, puts the module in the

same state as before shutdown.

A full predictible behaviour of a peripheral is not guaranteed during and after a cycle of stopping

and starting of its clock. So its recommended to stop a peripheral before stopping its clock with

PRR register.

Module shutdown can be used in Idle mode and Active mode to significantly reduce the overall

power consumption. In all other sleep modes, the clock is already stopped.

6.6.1 Power Reduction Register - PRR

•Bit 7 - Res: Reserved Bit

This bit is unused bit in the ATmega32/64/M1/C1, and will always read as zero.

• Bit 6 - PRCAN: Power Reduction CAN

Writing a logic one to this bit reduces the consumption of the CAN by stopping the clock to this

module. When waking up the CAN again, the CAN should be re initialized to ensure proper

operation.

• Bit 5 - PRPSC: Power Reduction PSC

Table 6-2. Active Clock Domains and Wake-up Sources in the Different Sleep Modes.

Active Clock Domains

Oscillator

s Wake-up Sources

Sleep

Mode

clk

CPU

clk

FLASH

clk

ADC

clk

PLL

Main Clock

Source Enabled

INT3..0

PSC

SPM/EEPROM

Ready

ADC

WDT

OtherI/O

Idle XXX X X X X XXX

ADC

Noise

Reduction

XX X X

(2)

XXXX

Power-

down

(2)

Standby

(1)

(2)

Bit 765432 1 0

- PRCAN PRPSC

PRTIM1 PRTIM0 PRSPI PRLIN PRADC PRR

Read/Write R R/W R/W R/W R/W R/W R/W R/W

Initial Value 0 0 0 0 0 0 0 0

1 2 ... 36 37 38 39 40 41 42 43 44 45 46 ... 365 366

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Rainbow-electronics ATmega64C1 Manuel d'utilisateur Page 41

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