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Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS"...
2.1 Applicable Scope This document provides repair instructions for technicians at service centers authorized by Huawei. This maintenance manual is confidential and accessible to authorized service centers (ASCs) and authorized service providers (ASPs) only. While every effort has been made to ensure the accuracy of this document, errors may still exist.
Principles and Failure Analysis 9.1 Block Diagram The MSM7X2XA (the U8666 uses the MSM7225A) is the baseband signal processing chip, mainly responsible for processing the input and output of IMGE, VIDEO, AUDIO, MEMEO SUPPORT, RF INTERFACES, and CONECTIVITY signals. The baseband chip provides keypad, LCD, SD card, Wi-Fi, Bluetooth, camera, and microphone interfaces.
9.3.3 Wi-Fi/Bluetooth/FM Module The U8666 uses a Wi-Fi/Bluetooth/FM 3-in-1 module (Broadcom's BCM4330). The Bluetooth and Wi-Fi functions share one antenna and one SP3T RF switch. The MSM7225A provides PCM and UART interfaces that are directly connected with the Bluetooth module's PCM and UART signal output.
9.4 Peripheral Circuits 9.4.1 Display The MSM7225A uses MIPI interfaces to send instructions and data to the LCD. The U8666's LCD uses MIPI interfaces, supporting a 60 Hz refresh rate, and requiring only one pair of differential clock signals and one pair of differential signals. The LCD also supports frame synchronization, using the MDP_VSYNC signals (GPIO_097) as data transmission synchronization signals to avoid screen tearing.
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GPIO10 (PM8029) U8666's LCD backlight control: The U8666 uses a 3.5-inch LCD whose backlight is provided by six LEDs connected in series. The backlight LEDs are controlled by the backlight driver chip TPS61160A. The ground resistance of the driver chip pin FB is set to 10 Ω, providing up to 20 mA current to the LEDs (duty:100%).
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MIPI_CSI2_LANE0_N Data communication signal NOTE The camera interface circuit is designed for compatibility with multiple types of cameras. The U8666 uses a 3.2-megapixel full-frame camera, so the CAM_VCM_PD_N and VREG_CAM_2P85 lines are not used. Issue 1.0 (2012-02-23) Huawei Proprietary and Confidential...
The HSED_MICBIAS (PM8029/HSED_BIAS1) supplies power to the headset microphone. The HSED_HSKEY_ADC (PM8029 MPP5) is used to detect the headset button press. NOTE The U8666 supports only LRGM headsets, and does not support LRMG headsets. Issue 1.0 (2012-02-23) Huawei Proprietary and Confidential...
Return the phone to the factory 9.4.5 Keys The U8666 has six keys, three of which are the Menu, Home and Back keys on the touchscreen panel. The MSM7225A's GPIO_42 and GPIO_41 pins are connected to the volume up and down keys.
Return the phone to the factory 9.4.6 Status Indicator and Touch Key Backlight Circuits The U8666's status indicator (tricolor indicator) provides red, green and blue light sources that are driven by the PM8029's three LED drivers. Light Driver Pin (PM8029)
I2C bus I2C1_SDA GPIO_132 DRDY COMPASS_INT GPIO_18 Compass interrupt signal 9.4.10 Proximity and Illuminance Sensor The U8666 has a proximity and illuminance sensor. The following figure shows the sensor circuit. Component Pin Network MSM7225A-0 Pin Description I2C1_SCL GPIO_131 I2C bus...
9.4.14 Touchscreen Panel The U8666's 3.5-inch capacitive touchscreen panel has a touch key area containing three touch keys. The backlight LEDs for the three touch keys are located on the PCBA. A light guide film is used to guide light from the LEDs to the touch key area.