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Chapter 3
Table 3-19. Power Button Interface Pin Signals (J46) (Continued)
3
RST_SW*
4
NC
5
NC
Note: The shaded table cell denotes power or ground. The * symbol indicates the signal is Active Low.
Miscellaneous
Real Time Clock (RTC)
The ICH7-M Southbridge contains a Real Time Clock (RTC) with 256 bytes of battery-backed memory. If
the battery is not present, the BIOS provides a battery-free boot option to complete the boot process. Under
these conditions all setup information is restored from flash memory during POST along with the default
date and time information.
NOTE
Some operating systems require a valid default date and time to function.
Temperature Monitoring
The Intel Atom processor supports the THERMTRIP# signal for catastrophic thermal protection. The
THERMTRIP# is an open drain signal from the processor which is used to shut down the processor core
voltage. This signal is connected to the THERMTRIP# input signal and indicates that a thermal trip from the
processor occurred and the ICH7-M will immediately transition to the S5 state.
NOTE
The LittleBoard 735 requires a heatsink for the Atom N270 processor.
User GPIO Signals
The LittleBoard 735 provides GPIO pins for custom use. The signals are routed to the J40 header, and the
Enable and Initialize values are set in the BIOS. An example of how to use the GPIO pins resides in the
Miscellaneous Source Code Examples on the LittleBoard 735 Support Software QuickDrive
The example program can be built by using the make.bat file. This produces a 16-bit DOS executable
application, gpio.exe, which can be run on the LittleBoard 735 to demonstrate the use of GPIO pins. For
more information about the GPIO pin operation, refer to the Programming Manuals for the Southbridge
(82801GBM) and Super I/O (SCH3114I-NU) controllers at:
http://www.intel.com/assets/pdf/datasheet/307013.pdf
http://www.smsc.com/main/catalog/sch311x.html
Table 3-20
lists the pin signals for the J40 GPIO interface, which provides a 10-pin header with two rows,
odd/even sequence, and 0.079" (2mm) pitch.
Table 3-20. User GPIO Pin Signals (J40)
Pin #
Signal
1
VCC
2
GND
3
GPI0
4
GPO0
5
GPI1
6
GPO1
7
GPI2
LittleBoard 735
Reset Switch input or output (connect between pins 3 & 2)
Not Connected
Not Connected
Description
+3.3 Volts DC +/ 5%
Ground
User defined
User defined
User defined
User defined
User defined
Reference Manual
Hardware
TM
.
39
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