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iPhone touch circuit repairing

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This video mainly explains the working principle of touch circuit from iPhone 6S to iPhone 8P

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The first step of the working principle, when the trigger is turned on,

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the main power supply will output more than 30 channels of power supply

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The 1.8V power supply will provide the working voltage for the touch screen

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Step 2, when starting to the display circuit,

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the display power supply will output the positive and negative 5.7V power supply of the touch screen

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Step 3, when starting to the touch circuit,

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the CPU sends a 32KHz clock signal for the touch screen

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Step 4, the CPU sends a reset signal to the touch screen

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Step 5, after the touch screen has the 1.8V power supply, positive and negative 5.7V power supply,

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the clock signal and the reset signal, some circuits of the touch screen will work first

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At this time, the CPU will read and detect the touch screen through the SPI bus

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Step 6, after the CPU reads and detects the touch screen,

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it will let the display power supply the 5.1V core power supply for the touch screen

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Step 7, after the touch screen has a 5.1V core power supply,

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all working conditions have been met

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At this time, the touch screen will send an interrupt signal to the CPU

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Step 8, after the CPU receives the interrupt signal,

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it will send touch data to the touch screen through the SPI bus

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At this time, the touch screen can work normally

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When troubleshooting no touch faults, we need to measure all the working conditions of the touch screen

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If one of the working conditions is abnormal, it will cause a no touch failure

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Ok, that's all for this video