LPC Interface

Chapter 3

Hardware

AC'97/HDA CODEC

The additional signals provided by J2 support AC'97 digital audio CODECs as well HDA (High Definition Audio) audio CODECs.

Table 3-12. Audio CODEC Interface Pin/Signal Descriptions (J2)

Pin #	Signal	Description
81	AC_RST*	AC'97/HDA CODEC Reset

85	AC_SYNC	AC'97/HDA Serial Bus Synchronization
89	AC_BIT_CLK	AC'97/HDA 12.228 MHz Serial Bit Clock from CODEC

82	AC_SDOUT	AC'97/HDA Audio Serial Data Output to CODEC

86	AC_SDIN0	AC'97/HDA Audio Serial Data Input from CODEC0
87	AC_SDIN1	AC'97/HDA Audio Serial Data Input from CODEC1
88	AC_SDIN2	AC'97/HDA Audio Serial Data Input from CODEC2

79	CODECSET	AC`97/HDA Disable onboard Audio CODEC

Notes: The shaded area denotes power or ground. The signals marked with * = Negative true logic.

The LPC (Low Pin Count) bus is provided as a replacement for the increasingly less often used ISA bus. The LPC bus is used on PC-style personal computers to connect low-bandwidth devices to the CPU, such as the boot ROM, "legacy" I/O devices (supported by a Super I/O chip), and audio controllers. The "legacy" I/O devices usually include serial and parallel ports, keyboard, mouse, and a floppy disk controller. Due to the software compatibility of the LPC bus to the ISA bus, I/O devices such as additional serial ports can be easily implemented on an application specific baseboard using the LPC bus. There are also many devices available for the LPC bus.

Table 3-13. LPC Interface Pin/Signal Descriptions (J2)

Pin #	Signal	Description
91	LPC_AD0	LPC Multiplexed Command, Address and Data Line 0
93	LPC_AD1	LPC Multiplexed Command, Address and Data Line 1

94	LPC_FRAME*	LPC Frame – Indicates start of a new or termination of a broken cycle.

95	LPC_AD2	LPC Multiplexed Command, Address and Data Line 2
96	LPC_DRQ0*	LPC Encoded DMA/Bus Master Request Line 0

97	LPC_AD3	LPC Multiplexed Command, Address and Data Line 3

98	LPC_DRQ1*	LPC Encoded DMA/Bus Master Request Line 1

Notes: The shaded area denotes power or ground. The signals marked with * = Negative true logic.

Extended System Management

The Extended System Management interface, implemented by the Super I/O chip (W83627HG), provide additional signals and functions to further improve system management. One of these signals is an output signal called FAN_PMOUT that allows system fan control using a PWM (Pulse Width Modulation) Output. Additionally there is an input signal called FAN_TACHOIN that provides the ability to monitor the system fan's RPMs (revolutions per minute).

XTX 820

Reference Manual