BCT-ETX-C3-XXX
S
INGLE
B
OARD
C
OMPUTER
I
NSTALLATION
Power control signals
PWGIN
An active-high input to the ETX from an external power supply, indicating that the power is good and that the
ETX can begin booting. Usage of this signal is not required because the ETX module contains its own power-
good logic. The PWGIN signal can also be used as an active-low reset input to the ETX module.
5V_SB
Power input for the internal suspend and power control circuitry. Connect to a 5V, 100mA stand-by power
source available. Should be connected to 5V supply if a standby supply is not available.
PS_ON
Active-low output from ETX module. Can be connected to the PS_ON input of an ATX power supply in order to
switch the main output. In order for this pin to function, 5V_SB must be supplied to the ETX module.
PWRBTN#
Power Button Input. Connect to GND with momentary-contact switch or open collector driver to implement
ATX power button control of PS_ON. In order for this pin to function, 5V_SB must be supplied to the ETX
module.
Power management signals
In order for these pins to function while VCC is powered down, 5V_SB must be supplied to the ETX module.
Note that these signals generally have pullup resistors to the suspend power supply inside the ETX module. Care
must be taken in interfacing these signals to logic that is powered down when 5V_SB is active.
RSMRST#
Resume Reset input. This input may be driven low by external circuitry in order to reset the
power management logic on the ETX module.
SMBALRT#
System Management Bus Alert input. May be driven low by SMB devices in order to signal an event on the SM
Bus.
BATLOW#
Battery low input. May be driven low by external circuitry to signal that the system battery is low, or may be
used to signal some other external power management event.
GPE1#
General purpose power management event input 1. May be driven low by external circuitry to signal an external
power management event. Within the ETX module, this pin is commonly connected to the chipset’s LID# input.
GPE2#
General purpose power management event input 2. May be driven low by external circuitry to signal an external
power management event. Within the ETX module, this pin is commonly connected to the chipset’s RING#
input.
EXTSMI
System management interrupt input. May be driven low by external circuitry to initiate an SMI.
Miscellaneous Signals
SPEAKER
PC speaker output signal. This logic-level signal can be connected to an external transistor in order to drive a
piezoelectric or dynamic speaker.
BATT
3V backup cell input. BATT is typically connected to a 3V lithium backup cell for RTC operation and CMOS
register non-volatility in the absence of system power. When RTC operation is not required by the application,
some ETX modules can back up CMOS contents to EEPROM so a battery is not needed.
I
2
CLK, I
2
DAT
These clock and data lines implement an I2C-bus.which supports external slave devices only. Data rate is
approximate 1-10kHz.. This interface is intended for support of EEPROMs and other simple I/O-devices
SMBDATA, SMBCLK
System Management Bus clock and data lines. May be used to support external SMBUS devices such as
temperature and battery monitoring chips. The addresses of external SMBUS devices must be chosen so they do
not conflict with addresses used internally on the ETX module.
KBINH
Keyboard Inhibit. Asserting this pin disables data input from the keyboard.
OVCR#