User manual

Advantech SOM-Express Design Guide
72 Chapter 5 Carrier Board Design Guidelines
SOM-Express
TV_DAC_A
TV_DAC_C
TV_DAC_B
Chipset
150ohm
150ohm
150ohm
Carrier board
Video
Filter
Video
Filter
Video
Filter
Connector
Zo=50O
Zo=50O
Zo=50O
Spacing
>50 mils
Spacing
Spacing
Spacing
>50 mils
>40 mils
>40 mils
150ohm
150ohm
150ohm
Zo=75O
Zo=75O
Zo=75O
MAX=0.2"
MAX=0.2"
MAX=0.2"
MAX=0.5"
MAX=0.5"
MAX=0.5"
3.3 V
3.3 V
3.3 V
TV
75 Ohm Coaxial Cable
Figure 5-37 TV DAC Routing Topology
5.9 Miscellaneous
5.9.1 Miscellaneous Signal Descriptions
Table 5.22 Miscellaneous signal descriptions
Pin Signal I/O Description
B32 SPKR O
This is the PC speaker output signal from the SOM-Express
module. Please connect this signal to the speaker.
B33 I2C_CK O General purpose I2C port clock output.
B34 I2C_DAT
I/O
OD
General purpose I2C port data I/O line.
A34 BIOS_DISABLE# I
Module BIOS disable input. Pull low to disable module BIOS.
Used to allow off-module BIOS implementations.
B27 WDT O Output indicating that a watchdog time-out event has occurred.
A86 KBD_RST# I
Input to module from (optional) external keyboard controller that
can force a reset. Pulled high on the module. This is a legacy
artifact of the PC-AT.
A87 KBD_A20GATE I
Input to module from (optional) external keyboard controller that
can be used to control the CPU A20 gate line. The A20GATE
restricts memory access to the bottom megabyte and is a
legacy artifact of the PC-AT. Pulled low on the module.
A93,B54
B57,B63
GPO[0:3] O
General purpose output pins. Upon hardware reset, these
outputs should be low.
A54,A63
A67,A85
GPI[0:3] I
General purpose input pins. Pulled high internally on the
module.
B13 SMB_CK
I/O
OD
System Management Bus bidirectional clock line. Power
sourced through 5 V standby rail and main power rails.
B14 SMB_DAT
I/O
OD
System Management Bus bidirectional data line. Power
sourced through 5 V standby rail and main power rails.
B15 SMB_ALERT# I
System Management Bus Alert – active low input can be used
to generate a SMI# (System Management Interrupt) or to wake
the system. Power sourced through 5 V standby rail and main
power rails.
C54
C57
D57
TYPE[0:2]# PDS
The TYPE pins indicate to the Carrier Board the Pin-out Type
that is implemented on the module. The pins are tied on the
module to either ground (GND) or are no-connects (NC). For
Pin-out Type 1, these pins are don’t care (X).