Design Note - Advantech SOM-ETX Series Design Manual

C86 BUSY#_MOT1
C88 PE_WDATA#
C90 SLCT_WGATE#
C51 LPT_FLPY#
5.10.2

Design Note

5.10.2.1 Parallel Port Implementation Notes
The pull-up resistors are not been implemented in all SOM modules, please refer to
Table 5.21 for detail. If the pull-up resistors are not been added-in, it should be
designed on baseboard for the signals that needed. In additional, it also can use a
PAC128404Q which includes pull-up, series termination, an EMI filter capacitor, and
ESD protection for the capacitors to implement parallel port design.
The diode in the pull-up power path can be add so that a powered parallel port
device (such as a printer) will not source current into the power plane of an un-
powered SOM-ETX module. Such phantom powering could interfere with the proper
operation of reset and power control circuits on the SOM-ETX module. If there is no
possibility of the parallel device being powered while the SOM-ETX module is not,
then the diode is unnecessary.
Table 5.21 Pull-high resistor in different SOM modules
SOM module
SOM-4481
SOM-4475
SOM-4472
SOM-4470
SOM-4451
SOM-4450
Advantech SOM-ETX Design Guide
Floppy OD When set to 0, this pin enable disk drive B
LPT OD This signal indicates the printer is busy and not
ready to receive new data
Floppy OD These active-low outputs select motor drives 1
LPT OD This signal indicates that the printer is out of paper
Floppy OD This active low output is a write-precompensated
serial data to be written onto the selected disk
drive. Each falling edge causes a flux change on
the media
LPT OD This active high output from the printer indicates
that it has power on
Floppy OD This active-low, high-drive output enables the write
circuitry of the selected disk drive
- I This signal selects whether LPT or Floppy interface
will be used with SOM-ETX-interface. The following
signals are multifunctional and depending on level
of signal LPT/FLPY# LPT-interface (LPT/FLPY#:
nc., default) or Floppy-interface (LPT/FLPY#: low)
will be used
LPT pull-up resistors
Not implement
Implement
Implement
Not implement
Not implement
Not implement
Chapter 5 Carrier Board Design Guidelines
Floppy pull-up resistors
Leave pads
Leave pads
Implement
Not implement
Leave pads
Not implement
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