LG KE990 Service Manual - Page 35

3. TECHNICAL BRIEF 3.6.10 Wideband CODEC The ESM6270 device integrates a wideband voice/audio CODEC into the mobile station modem (ESM). 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 ESM 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. 3.6.13 Mode Select and JTAG Interfaces The mode pins to the ESM6270 device determine the overall operating mode of the ASIC. The options under the control of the mode inputs are Native mode, which is the normal subscriber unit operation, ETM mode, which enables the built-in trace mode, and test mode for factory testing. The ESM6270 device meets the intent of the ANSI/IEEE 1149.1A-1993 feature list. The JTAG interface can be used to test digital interconnects between devices within the mobile station during manufacture. LGE Internal Use Only - 36 - Copyright © 2008 LG Electronics. Inc. All right reserved. Only for training and service purposes