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iPhone connection circuit repairing

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This video mainly explains the working principle of the iPhone 12 series connection circuit

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There are two differences between the iPhone 12 series connection circuit and the earlier models

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First, the USB chip has PP_VDD_MAIN main power supply

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Second, the data bus from USB to CPU is connected to the data conversion tube

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Let's start to explain the principle

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Step 1, when the battery is buckled or the adjustable power supply is connected,

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the main power supply will be generated,

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and the main power supply will provide the working voltage for the USB chip

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Step 2, after the iPhone is triggered,

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the main power supply will provide 1.2V and 3.0V power supply for the USB chip

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after receiving the power-on signal

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Step 3, after the CPU works normally, it will detect the USB chip through the I2C bus,

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and the iPhone will enter the system after the detection is passed

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Step 4, when copying the iPhone data, we plug in the data cable,

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and the data cable insertion detection signal DETECT will be sent to the USB chip through the charging connector

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Step 5, after the USB chip receives the DETECT signal,

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it will send the data line ID identification signal to the main power supply

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Step 6, after the main power supply receives the ID signal,

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it will send an identification signal to the CPU

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The CPU controls the ACC power supply chip through the I2C bus

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to generate ACC power supply and send it to the USB chip

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Step 7, after the USB chip receives the ACC power supply, it will convert ACC1 and ACC2 power supplies,

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and send them to the data line through the charging connector

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ACC1 and ACC2 are the power supply voltages on the front and back of the data line

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Step 8, after the data line has power supply,

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it will send the verification information of the computer connection to the USB chip

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through the DP1 and DP2 buses

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Step 9, after the USB chip receives the connection information, it sends an interrupt signal to the CPU

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Step 10, after the CPU receives the interrupt signal,

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it will read the connection information through the UART bus

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After the verification information is read, a "Add Trust" prompt will pop up on the screen

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After clicking Trust, it will pop up a prompt to enter the screen unlock password

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When we enter the password, the iPhone and computer can establish a connection

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Step 11, when copying data on the computer,

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the CPU will read the data stored in the hard disk and send it to the USB chip through the USB bus

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Step 12, after the USB chip receives the data, it sends it to the data line through the DP1 and DP2 buses,

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and then sends it to the computer

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At this time, the progress of copying data will be displayed on the computer

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If there is no response when we plug in the data cable, it means that the connection circuit is faulty

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First, we can replace the USB chip

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If it is still not normal after replacement, we check the working conditions of the USB chip

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That's all for this video