Rainbow-electronics ATmega8515L Uživatelský manuál stáhnout pdf (Strana 38)

ATmega8515(L)

2512A–AVR–04/02

Power Management

and Sleep Modes

Sleep modes enabletheapplication to shut down unused modules in the MCU, thereby

saving power.TheAVRprovides varioussleep modes allowing theuser to tailor the

powerconsumption to theapplication’srequirements.

To enter any of thethree sleep modes, the SE bit in MCUCRmust be written to logic

one and a SLEEPinstruction must beexecuted.The SM2 bit in MCUCSR, the SM1 bit

in MCUCR, and the SM0 bit in the EMCUCR Registerselect which sleep mode (Idle,

Power-down, orStandby) will beactivatedbythe SLEEPinstruction. See Table16for a

summary. If an enabled interruptoccurs whilethe MCU is in a sleep mode, the MCU

wakes up.The MCU is then haltedforfour cycles in addition to the start-up time, it exe-

cutes theinterrupt routine, andresumes execution from theinstruction following SLEEP.

The contents of the registerfileandSRAM are unalteredwhen the device wakes up

from sleep. If aReset occurs during sleep mode, the MCU wakes up and executesfrom

theReset Vector.

Figure17 on page 31 presents the different clock systems in the ATmega8515, and

theirdistribution. The figureishelpful in selecting an appropriate sleep mode.

MCU Control Register –

MCUCR

• Bit5–SE:SleepEnable

The SE bit must be written to logic onetomakethe MCU enter the sleep mode when the

SLEEPinstruction is executed.Toavoid the MCU entering the sleep modeunless it is

the programmers purpose, it isrecommended to write the SleepEnable (SE) bit to one

just beforetheexecution of the SLEEPinstruction and to clear it immediately afterwak-

ing up.

• Bit 4 – SM1: Sleep Mode Select Bit 1

The SleepMode Select bitsselect between thethree available sleep modes asshown

in Table16.

MCU Control and Status

• Bit 5 – SM2: Sleep Mode Select Bit 2

The SleepMode Select bitsselect between thethree available sleep modes asshown

in Table16.

Extended MCU Control

Bit 76543 210

SRE SRW10 SE SM1 ISC11 ISC10 ISC01 ISC00 MCUCR

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

Initial Value00000000

Bit 76543 210

– –SM2– WDRF BORF EXTRF PORF MCUCSR

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

Initial Value00000000

Bit 76543 210

SM0

SRL2 SRL1 SRL0 SRW01 SRW00 SRW11 ISC2 EMCUCR

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

Initial Value00000000

1 2 ... 33 34 35 36 37 38 39 40 41 42 43 ... 222 223

Komentáře k této Příručce

Žádné komentáře

Rainbow-electronics ATmega8515L Uživatelský manuál Strana 38

Komentáře k této Příručce

Související produkty a manuály pro Senzory Rainbow-electronics ATmega8515L