STPC STMicroelectronics, STPC Datasheet - Page 20

• Manufacturer Part Number: STPC
• Description: PC Compatible Embeded Microprocessor
• Manufacturer: STMicroelectronics

www.DataSheet4U.com
PIN DESCRIPTION
ed to ISAOE# and the output is provided with a
weak pull-up resistor.
RTCRW# / DD[13] Real Time Clock RW. This pin
is a multi-function pin. When ISAOE# is active,
this signal is used as RTCRW#. This signal is as-
serted for any I/O write to port 71H.
When ISAOE# is inactive, this signal is used as
IDE DD[13] signal.
This signal must be ORed externally with ISAOE#
and then connected to the RTC. An LS244 or
equivalent function can be used if OE is connect-
ed to ISAOE# and the output is provided with a
weak pull-up resistor.
RTCDS# / DD[12] Real Time Clock DS . This pin is
a multi-function pin. When ISAOE# is active, this
signal is used as RTCDS. This signal is asserted
for any I/O read to port 71H.
When ISAOE# is inactive, this signal is used as
IDE DD[12] signal.
This signal must be ORed externally with ISAOE#
and is then connected to RTC. An LS244 or equiv-
alent function can be used if OE# is connected to
ISAOE# and the output is provided with a weak
pull-up resistor.
RTCAS# Real time clock address strobe. This sig-
nal is asserted for any I/O write to port 70H.
2.2.12 Monitor Interface
RED, GREEN, BLUE RGB Video Outputs. These
are the 3 analog color outputs from the RAMDACs
VSYNC Vertical Synchronisation Pulse. This is
the vertical synchronization signal from the VGA
controller.
20/51
Issue 1.2
HSYNC Horizontal Synchronisation Pulse. This is
the horizontal synchronization signal from the
VGA controller.
VREF_DAC DAC Voltage reference. An external
voltage reference is connected to this pin to bias
the DAC.
RSET Resistor Current Set. This is reference cur-
rent input to the RAMDAC is used to set the full-
scale output of the RAMDAC.
COMP Compensation. This is the RAMDAC com-
pensation pin. Normally, an external capacitor
(typically 10nF) is connected between this pin and
V
DDC[1:0] Direct Data Channel Serial Link. These
bidirectional pins are connected to CRTC register
3Fh to implement DDC capabilities. They conform
to I
collector output drivers which are internally con-
nected to V
They can instead be used for accessing I C devic-
es on board. DDC1 and DDC0 correspond to SCL
and SDA respectively.
COL_CMP Color Compare Output . Allows access
to the video signal which flags when there is a
color compare hit. This signal is multiplexed with
SMEMEW# on the ISA Bus. The signal is selected
by setting Strap Option MD[0] as described in Sec-
tion 3.
2.2.13 MISCELLANEOUS
SCAN_ENABLE Reserved . The pins are re-
served for Test and Miscellaneous functions)
DD
2
C electrical specifications, they have open-
to damp oscillations.
DD
through pull-up resistors.