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Hello everyone, today we are going to learn about the working conditions of SMC

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SMC is also known as EC

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The EC is in the working state whether in the standby state or on state

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Let's take a look at how it works in standby mode

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First of all, EC has four working conditions

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

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Standby supply voltage is 3.3V

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Common EC standby power supply names are VBAT and VDDA

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In the circuit diagram,

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we can find that this is its power supply pin, VBAT

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The VDDA is also the power supply pin, and there is a VDD next to the VBAT

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This power supply is provided to an external standby power supply PP3V42_G3H

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For slightly newer machines,

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the standby power name is no longer PP3V42_G3H, but PP3V3_G3H

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Standby clock of the EC

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Next to the EC there is a crystal oscillator, this one is a 12MHz crystal oscillator,

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connected to these two pins of the EC

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When the EC meets the power supply, the crystal will vibrate

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Without this power supply, the crystal will not work

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The EC then delays to get a reset signal,

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which is called RST internally and SMC_RESET_L externally

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It is a high level reset signal sent by the voltage detection chip

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after detecting that the EC standby power supply is normal, and the high level is 3.3V

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

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it will read the program and configure the GPIO pin

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Because there are many GPIO pins within the EC,

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they need to be defined by the program and their functionality assigned by the program

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The EC will not work properly until these GPIO pins are configured programmatically

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The program resides inside the EC, or it can be called the EC's firmware

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EC internal program, we currently have no way to write through the programmer

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Therefore, when we encounter EC damage in the maintenance,

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we had to find the same mainboard to remove the EC

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Well, these are EC's working conditions