Reverse Engineering Microcontroller ATmega644PA Firmware

Note that if a level triggered interrupt is used for wake-up from Power-down mode, the changed level must be held for some time to wake up the procedures of Reverse Engineering Microcontroller ATmega644PA Firmware.

Refer to “External Interrupts”. When waking up from Power-down mode, there is a delay from the wake-up condition occurs until the wake-up becomes effective by Recover IC ST62T65C6 Software. This allows the clock to restart and become stable after having been stopped.

The wake-up period is defined by the same CKSEL Fuses that define the Reset Time-out period, as described in “Clock Sources” on page 40. When the SM2..0 bits are written to 011, the SLEEP instruction makes the MCU Cracking enter Power-save mode.
This mode is identical to Power-down, with one exception: If Timer/Counter2 is enabled, it will keep running during sleep. The device can wake up from either Timer Overflow or Output Compare event from Timer/Counter2 if the corresponding Timer/Counter2 interrupt enable bits are set in TIMSK2 to facilitate the process of Attack MCU MSP430G2452IPW14R Heximal, and the Global Interrupt Enable bit in SREG is set.
If Timer/Counter2 is not running, Power-down mode is recommended instead of Power-save mode. The Timer/Counter2 can be clocked both synchronously and asynchronously in Power-save mode. If the Timer/Counter2 is not using the asynchronous clock, the Timer/Counter Oscillator is stopped during sleep.

If the Timer/Counter2 is not using the synchronous clock, the clock source is stopped during sleep. Note that even if the synchronous clock is running in Power-save, this clock is only available for the Timer/Counter2 in order to Attack IC TMS320F28232PGFA Software.

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.

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