Signal Description
2-10
Intel
82801BA ICH2 Datasheet
2.14
Real Time Clock Interface
2.15
Other Clocks
2.16
Miscellaneous Signals
Table 2-14. Real Time Clock Interface
Name
Type
Description
RTCX1
Special
Crystal Input 1:
This signal is connected to the 32.768 KHz crystal. If no
external crystal is used, then RTCX1 can be driven with the desired clock rate.
RTCX2
Special
Crystal Input 2:
This signal is connected to the 32.768 KHz crystal. If no
external crystal is used, then RTCX2 should be left floating.
Table 2-15. Other Clocks
Name
Type
Description
CLK14
I
Oscillator Clock:
This signal is used for 8254 timers. Runs at 14.31818 MHz. This
clock is permitted to stop during S3 (or lower) states.
CLK48
I
48 MHz Clock:
This signal is used to run the USB controller. Runs at 48 MHz. This
clock is permitted to stop during S3 (or lower) states.
CLK66
I
66 MHz Clock:
This signal is used to run the hub interface. Runs at 66 MHz. This
clock is permitted to stop during S3 (or lower) states.
Table 2-16. Miscellaneous Signals
Name
Type
Description
SPKR
O
Speaker:
The SPKR signal is the output of counter 2 and is internally "ANDed"
with Port 61h bit 1 to provide Speaker Data Enable. This signal drives an external
speaker driver device, which in turn drives the system speaker. Upon PCIRST#, its
output state is 1.
Note: SPKR is sampled at the rising edge of PWROK as a functional strap. See
Section 2.20.1
for more details.
RTCRST#
I
RTC Reset:
When asserted, this signal resets register bits in the RTC well and
sets the RTC_PWR_STS bit (bit 2 in GEN_PMCON3 register). This signal is also
used to enter the test modes documented in
Section 2.20.2
.
Note: Clearing CMOS in an ICH2-based platform can be done by using a jumper
on RTCRST# or GPI, or using SAFEMODE strap. Implementations should not
attempt to clear CMOS by using a jumper to pull VccRTC low.
TP[0]
I
Test Point:
This signal must have an external pull-up to VccSus3_3.
FS[0]
I
Functional Strap:
This signal is reserved for future use. There is an internal pull-
up resistor on this signal.
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