Wideband Codec; Vocoder Subsystem; Hkadc; General-Purpose Input/Output Interface - LG U8500 Service Manual

3. TECHNICAL BRIEF

3.8.6 Wideband CODEC

The MSM6250 device integrates a wideband voice/audio CODEC into the mobile station modem
(MSM). The CODEC supports two differential microphone inputs, one differential earphone output, one
single-ended earphone output, and a differential analog auxiliary interface on two single-ended
earphone output. The CODEC integrates the microphone and earphone amplifiers into the MSM6250
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
externally. The Rx/Tx paths are designed to meet the ITU-G.712 requirements for digital transmission
systems.

3.8.7 Vocoder Subsystem

The MSM6250 device's QDSP4000 supports AMR vocoder. 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 MSM6200 device's integrated ARM7TDMI processor
downloads the firmware into the QDSP4000 and configures QDSP4000 to support the desired
functionality.

3.8.8 HKADC

TheMSM6250 device has an on-chip 8-bit analog-to-digital converter (ADC) which is intended to
digitize DC signals corresponding to analog parameters such as battery voltage, temperature, and RF
power levels. The MSM6250 device has six analog input pins which are multiplexed to the input of the
internal HKADC.

3.8.9 General-Purpose Input/Output Interface

The MSM6250 device has general-purpose bidirectional input/output pins. Some of the GPIO pins
have alternate functions supported on them. The alternate functions include USB interface, additional
RAM, ROM, general-purpose chip selects, parallel LCD interface, and UART interface.
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