Utility Interface

Chapter 3

Hardware

External Power-On Switch

This control signal is provided externally through a switch by connecting ground pin 8 to pin 6 on the Utility connector (J17).

External Reset Switch

This control signal is provided through an external switch by connecting ground pin 12 to pin 10 on the Utility connector.

NOTE To perform the equivalent of a power-on reset, the reset button must be pressed and held for a minimum of three seconds.

External Speaker (Beep)

The Beep signals from the I/O Hub (82801FB) and the Super I/O (W83627HF) are fed to pin 13 of the Utility connector through an OR circuit, in conjunction with +5V (pin 7), and drives an external PC Beep speaker. The PC Beep speaker signal from the I/O Hub (Southbridge) is also fed to the on-board Audio CODEC (ALC202A) to provide a PC Beep signal for the Line out connections.

External Power-On LED

This indicator signal is fed to pin 1 and pin 5 of the Utility connector for an external LED to indicate power is applied to the MightyBoard 821.

External IDE Activity LED

This indicator signal is fed to pin 2 and pin 4 of the Utility connector for an external LED to indicate power is applied to the MightyBoard 821.

Table 3-8. Utility Interface Pin/Signal Descriptions (J17)

Pin #	Signal	Description
1	PwrLED	Power-On LED – External Power-On LED is connected between +5 Volts
		through 330 ohm resistor at pin 1, to ground at pin 5.

2, 3	VCC	+ 5 Voltage – Goes to +5 volts through 330-ohm resistor.
4	IDELED	IDE Activity LED – External IDE Activity LED connection from Primary IDE
		channel through Or circuit. Connect external Power-On LED between pin 2 (+5 V)
		and pin 4 (IDE_LED).

5, 8, 12	GND	Ground
6	PWRSW	Power-On Switch – Connects external Power-On switch between pin 6 and ground
		at pin 8.

7	VCC	+5 volts – Provides +5 volts to external device (PC “Beep” speaker).
9, 11,	NC	Not connected
14, 15,
16

10	RST	Reset Switch – External Reset switch connection sends reset signal to Super I/O
		chip. Connect external Reset Switch between pin 10 and ground, pin 12.

13	SPK	PC Speaker (Beep) – Provides PC beep speaker output to external speaker. Connect
		external PC Beep Speaker between pin 7 (+5V) and pin 13.

Note: The shaded area denotes power or ground.

Reference Manual

MightyBoard 821