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Hello everyone, today let's learn about the standby condition of the Apple EC

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This lesson is divided into two parts,

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one is the introduction of Apple EC,

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the other is the standby condition of Apple EC

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First, let's take a look at the introduction of Apple EC

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EC refers to embedded controller,

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it is a single chip microcomputer, we can also call it MCU

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The EC controls the timing of most important signals during system startup

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In the shutdown state,

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the EC keeps running and waits for the user's startup information

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After being turned on, the EC controls various indicators, fans and other devices

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It even controls the standby, sleep and other states of the system,

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and monitors the voltage and current of each supply

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There is a slight difference between the Apple EC and the normal laptop EC

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Apple's EC doesn't have a management for keyboard or touchpad,

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and Apple's EC comes with built-in programs

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During the maintenance, if the EC is to be replaced, the same board must be found

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Ok, let's take a look at the standby condition of the Apple EC

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The standby conditions of Apple EC are divided into four categories

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They are standby power supply, standby clock, standby reset, and EC program

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First of all, the standby power supply is 3.3V,

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and the common names in the circuit diagram are VBAT and VDDA

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It is usually provided by PP3V42_G3H, or PP3V3_G3H

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The standby clock of the EC is provided by a 12MHz crystal,

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which is usually located next to the EC

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The standby reset of the EC is usually named RST* in the circuit diagram,

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and the external name is usually SMC_RESET_L

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This signal is usually high at 3.3V

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If it is low, the EC will be reset

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The EC program is stored inside the EC

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After the EC meets the requirements of standby power supply, clock, and reset,

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it needs to read its own internal program to configure its GPIO pin,

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and then it can work normally

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GPIO refers to General Purpose Input Output pins

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Before the GPIO pin is configured,

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It is in a high resistance, uncontrolled state

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Ok, so that's the standby condition of the Apple EC