Function Description Of The Pcba - Huawei U8655N Maintenance Manual

U8655
Maintenance Manual
Providing analog multi-channel switch, real-time clock circuit, TCXO clock circuit, motor
driver circuit, and speaker driver circuit.
The RTR6285A is the RF signal processing chip, responsible for converting UMTS/GSM
uplink/downlink RF signals and using I/Q signals to exchange data with the baseband chip.

9.1.1 Function Description of the PCBA

The PCBA can be divided into four sub-systems: baseband, RF, power supply, and user
interfaces. The following table describes the subsystems' modules and units, as well as their
functions.
Table 9-1 PCBA subsystems' modules, units, and functions
Subsystem Module
Baseband MSM7225A
subsystem
PM8029
NAND flash
memory
DDR1 RAM
RF WCDMA, and
subsystem GSM/DCS
signal
transmission and
reception
Issue 1.0 (2012-02-23)
Unit
Modem subsystem
Application
subsystem
User interface
processing unit
Multimedia and
game engine
Power supply voltage
monitoring
Temperature
monitoring
File system support
Random access
memory
AFC circuit, APC
circuit, AGC circuit
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Copyright © Huawei Technologies Co., Ltd.
9 Principles and Failure Analysis
Function
The modem subsystem includes the ARM11
processor, modem DSP, modem AHB bus,
interruption controller, and sleep controller.
The ARM9 is a 400 MHz modem processor,
responsible for modulation and demodulation of
WCDMA, GPS, and GSM signals.
The subsystem includes ARM A5 processor,
application DSP, and dedicated data mover.
The A5 processor has a clock rate of 800 MHz,
supporting function modules such as the microSD
card, EBI2, UART/USIM, I2C, GPIO, and clock
modules.
Provides camera, PCM, broadband codec, vocoder,
RF, HKADC, LCD, SD card, USB, UART, USIM
card, SBI, GPIO, JTAG/ETM, and keypad
interfaces.
The multimedia and game engine is an MPEG/JPEG
hardware engine providing Java acceleration and
MP3/MMS/MIDI/VR processing functions.
Lists objects being monitored, such as the external
power supply input, Li-ion battery, and charger.
Monitors the battery temperature.
Stores applications and NV items. Capacity: 4 GB.
Provide storage space for running applications.
Capacity: 2 GB.
Performs the RF function of WCDMA signal
reception and transmission.
Mainly includes the RTR6285A RF chip and the
peripheral circuit.
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