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iPhone Wi-Fi circuit repairing

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This video mainly explains the working principle of iPhone XS and XS Max Wi-Fi circuit

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The working principles of these two models are the same

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Wi-Fi working principle step 1

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When the battery is buckled or the adjustable power supply is connected,

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the PP_VDD_MAIN main power supply will be generated

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The main power supply will first provide the working voltage for the Wi-Fi chip

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Step 2, after triggering the boot,

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the main power supply will output 1.8V power supply to provide working voltage for Wi-Fi

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Step 3, the main power supply outputs a 32KHz clock signal for the Wi-Fi chip

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Step 4, after the Wi-Fi chip has the previous power supply and clock signal,

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the internal power supply conversion module starts to work,

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and will convert 1.12V and 0.9V power supply for itself

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Step 5, when booting to the Wi-Fi circuit,

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the CPU first sends a wake-up signal to wake up the Wi-Fi chip

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Step 6, when the Wi-Fi chip has three-way power supplies, clock signal, and open signal,

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The CPU will detect the Wifi chip through the PCIE bus

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After the CPU detects the Wi-Fi chip,

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we can see the Wi-Fi address on the About This iPhone interface

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If there is no Wi-Fi address, it means that the CPU has not detected the Wi-Fi chip

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Step 7, after the Wi-Fi chip communicates with the CPU,

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the Wi-Fi chip can work normally, and the signal transceiver circuit is turned on

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In the transceiver circuit, 2.4G and 5G signals will all start working, search for router signals

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Step 8, the Wi-Fi chip sends the searched router signal to the CPU through the UART bus,

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and the router name will be displayed on the screen

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Step 9, when we select the router signal and enter the password,

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the CPU will send the password data to the Wi-Fi chip through the UART bus

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Step 10, the Wi-Fi chip sends the received password information to the router

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through the antenna signal for verification

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If the verification is successful, it will establish a connection with the mobile phone

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Step 11, the Wi-Fi chip sends the received data to the CPU through the PCIE bus

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At this time, the mobile phone realizes the Internet function

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The UART bus is the bus used by the baseband to transmit data

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For example, if the mobile phone turns on the hotspot function,

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it will use the signal of the baseband to Wi-Fi to transmit

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In the functional circuit diagram, the main working conditions of the Wi-Fi are shown on the left

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If one is damaged, it will cause the Wi-Fi to not turn on

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The right side of Wi-Fi is the signal transmission and receiving line

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If a problem occurs, the Wi-Fi signal cannot be searched or the Wi-Fi signal is weak

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Ok, that's all for this video