HP D315 manual Audio Subsystem, Functional Analysis

Chapter 5 Input/Output Interfaces

5.8AUDIO SUBSYSTEM

This system includes an embedded Sound Blaster-compatible audio subsystem with front panel- accessible headphone and microphone jacks.

5.8.1 FUNCTIONAL ANALYSIS

A block diagram of the audio subsystem is shown in Figure 5-10. These systems use the AC’97 Audio Controller of the MCP component to access and control an Analog Devices AD1885 or AD1981B Audio Codec, which provides the analog-to-digital (ADC) and digital-to-analog (DAC) conversions as well as the mixing functions. All control functions such as volume, audio source selection, and sampling rate are controlled through software over the PCI bus through the AC97 Audio Controller of the MCP component. Control data and digital audio streams (record and playback) are transferred between the Audio Controller and the Audio Codec over the AC97 Link Bus.

This system incorporates Business Audio, which has the codec stereo analog output applied through headphone jacks and switch logic to a mono 3-watt amplifier that drives a 16-ohm speaker. The switch logic allows the system to provide headphone functionality with or without the front panel assembly installed.

The analog interfaces allowing connection to external audio devices include:

Mic In - This input uses a three-conductor (stereo) mini-jack that is specifically designed for connection of a condenser microphone with an impedance of 10-K ohms. This is the default recording input after a system reset. Either the front or rear panel microphone jack is available for use (but not simultaneously).

Line In - This input uses a three-conductor (stereo) mini-jack that is specifically designed for connection of a high-impedance (10k-ohm) audio source such as a tape deck.

Headphones Out - This input uses a three-conductor (stereo) mini-jack that is designed for connecting a set of 16-ohm (nom.) stereo headphones or powered speakers. Plugging into the Headphones jack mutes the signal to the internal speaker.

Line Out - This output uses a three-conductor (stereo) mini-jack for connecting left and right channel line-level signals (20-K ohm impedance). A typical connection would be to a tape recorder’s Line In (Record In) jacks, an amplifier’s Line In jacks, or to powered speakers that contain amplifiers. Plugging into the Line Out mutes the internal speaker.

5-26Compaq D315 and hp d325 Personal Computers Featuring the AMD Athlon XP Processor

Second Edition – April 2003