LG KF690 Service Manual page 31

3. TECHNICAL BRIEF
3.6.9 Serial Bus Interface(SBI)
The ESM6270 device's SSBI is designed specifically to be a quick, low pin count control protocol for
QUALCOMM's RTR6235, RFR6275 and PM6635 ASICs. Using the SSBI, the RTR6235, RFR6275,
and PM6635 devices can be configured for different operating modes and for minimum power
consumption, extending battery life in Standby mode. The SSBI also controls DC baseband offset
errors.
3.6.10 Wideband CODEC
The ESM6270 device integrates a wideband voice/audio CODEC into the mobile station modem
(ESM6270). The CODEC supports two differential microphone inputs, one differential earphone
output, one single-ended earphone output, and a differential analog auxiliary interface.
The CODEC integrates the microphone and earphone amplifiers into the ESM6270 device, reducing
the external component count to just a few passive components. The microphone (Tx) audio path
consists of a two-stage amplifier with the gain of the second stage set interally. The Rx/Tx paths are
designed to meet the ITU-G.712 requirements for digital transmission systems.
3.6.11 Vocoder Subsystem
The ESM6270 device's QDSP4000 supports AMR,FR,EFR and HR. In addition, the QDSP4000 has
modules to support the following audio functions: DTMF tone generation, DTMF tone detection, Tx/Rx
volume controls, Tx/Rx automatic gain control (AGC), Rx Automatic Volume Control(AVC), EarSeal
Echo Canceller (ESEC), Acoustic Echo Canceller (AEC), Noise Suppression(NS), and programmable,
13-tap, Type-I, FIR, Tx/Rx compensation filters. The ESM6270 device's integrated ARM9TDMI
processor downloads the firmware into the QDSP4000 and configures QDSP4000 to support the
desired functionality.
3.6.12 ARM Microprocessor subsystem
The ESM6270 device uses an embedded ARM926EJ-S microprocessor. This microprocessor, through
the system software, controls most of the functionality for the ESM6270 device, including control of the
external peripherals such as the keypad, LCD, RAM, ROM, and EEPROM devices. Through a generic
single serial bus interface (SSBI) the ARM926EJ-S configures and controls the functionality of the
RFR6275, RTR6235, and PM6635 devices.
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