Standby mode, Extended standby mode, Atmega128(l) – Rainbow Electronics ATmega128L User Manual

Page 43

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ATmega128(L)

2467B–09/01

asynchronous timer should be considered undefined after wake-up in Power-save Mode
if AS0 is 0.

This sleep mode basically halts all clocks except clk

ASY

, allowing operation only of asyn-

chronous modules, including Timer/Counter0 if clocked asynchronously.

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 6 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 6 clock cycles.

Notes:

1. External Crystal or resonator selected as clock source
2. If AS

bit in ASSR is set

3. Only INT3:0 or level interrupt INT7:4

Table 18. Active Clock Domains and Wake Up Sources in the Different Sleep Modes

Active Clock Domains

Oscillators

Wake Up Sources

Sleep
Mode

clk

CPU

clk