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Terms explanation

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This video mainly explains the meaning and identification of common terms in the schematic diagram

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In the working conditions of the chip,

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except for the power supply and grounding, all belong to the signal

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But when the chip is working,

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it will divide the signal into different signals to realize different commands

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The signal includes clock signal, reset signal,

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enable signal, interrupt signal, and wake-up signal

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These signals will execute different commands when the chip is working,

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so their working meanings are also different

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The clock signal is identified by English CLK in the schematic diagram

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The clock signal is designed to provide a reference operating frequency for the chip

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A chip or device lacks a clock signal and cannot function

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The basic unit of the clock is Hertz

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For example, CLK_PMU_TO_TOUCH_32K_1V8,

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this signal belongs to the clock signal, which is the 32KHz clock signal from power supply to touch

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The reset signal is identified by the English letter RST,

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and reset means to restart operation

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For example, when we're playing games or watching movies on a desktop computer,

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suddenly it freezes, you may need to press the restart button

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After pressing restart, the computer will restart

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When the mobile phone is turned on,

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the chip also needs a reset signal

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Without a reset signal, the chip cannot function properly

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The reset signal is active at an instant low level,

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which generally means that the reset pin has no voltage at the moment of power-on,

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and the pin will have voltage after this time point

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Measure the reset signal during maintenance,

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the voltage is mostly 1.8V

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For example, in the picture, AOP_TO_CODEC_RESET

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This signal refers to the reset signal from the CPU to the large audio,

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which is specially used to reset the audio chip

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The enable signal is generally identified by the English letter EN

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In the schematic diagram, some will use PWDN, SHUTDOWN to identify

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Enable signal means that when the chip is working,

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there needs to be a command

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After this command, the chip can work normally

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For example, TOUCH_TO_VDDH_EN in the picture,

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then the signal refers to the enable signal from the touchpad to the power supply

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Interrupt signal

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The interrupt signal is identified by English INT

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Interruption means that when we are playing games on the mobile phone,

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a call comes in suddenly,

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and the game will be interrupted at this time,

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and then it will display the answering call

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After answering the call, return to the game to run,

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then this process refers to the interruption

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For example, in the picture,

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AP_FROM_CODEC_INT refers to the CPU interrupt signal from the audio

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The wake-up signal uses the English WAKE logo

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Wake up means that when the mobile phone is not in use,

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the mobile phone will automatically turn off the screen and enter sleep mode

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When using the mobile phone, press the HOME button,

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the circuit will automatically send a wake-up signal,

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and the screen will light up

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For example, in the schematic diagram,

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PMU_FROM_CODEC_WAKE represents the wake-up signal from the audio to power supply

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The signals mentioned just now belong to the working conditions of the chip

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When the mobile phone fails, it is necessary to check these working conditions,

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so these signals are not required by every chip

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When we search, as long as the signal can be found,

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it means that the chip needs

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If you can't find it, it means that the chip does not need

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Ok, that's it for this video