Themis NanoPAK, User Manual

Page: 41 / 156

2-9
Themis Computer
2—Installation and Operation
2.3 Input and Output
2.3.1 USB Ports
Four USB 2.0 ports are provided. USB0 and USB1 support a greater current load
than allowed by the USB standard. The peripheral attached to these ports may draw
a maximum 2A current instead of the usual 500mA, but only temporarily, and may
not be sustained. USB2 and USB3 have standard current limitation of 500mA.
2.3.2 Serial Ports
Two native legacy serial ports from x86 architecture are available on the 69-pin IO
connector.
2.3.2.1 COM A
COM A is configurable via solder bead setting for RS232, RS422, or RS485 mode.
In RS232 mode, it supports modem control signals (RTS, CTS, DCD, DTR). (In this
mode, the GPO/GPI ports share the same pins on the connector with the modem con-
trol signals to make connections available for the SATA pairs. This is reflected in the
following table. For systems with no SATA provisions, the GPI/O signals do not
share pins.) In RS422 or full-duplex RS485 mode, only the transmit and receive dif-
ferential pairs are provided. In RS485 half-duplex mode, one pair, (common for
transmit and receive), is active. Six pins of J1, the 69-pin external connector, are
assigned to attach a serial device to COM A. The following table shows how they
are used in each mode. (See
Table 2-3 ).
Table 2-3. COM A Modes and Signals
Sig.
J1
Pin
RS232 RS422
RS485
Full Duplex
(FDX)
RS485
Half-Duplex
(HDX)
Ser0
Ser1
Ser4
Ser5
Ser2
Ser3 14
16
15
17
39
62 RTS or GPO2
CTS or GPI2
TXD
RXD
DTR or GPO3
DCD or GPI3
TXD+
RXD+
TXD(-)
RXD(-)
TXD+
RXD+
TXD(-)
RXD(-)
TX/RXD+
TX/RXD(-)