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Chapter 3 Hardware
20 Reference Manual MightyBoard 821
Note: The shaded area denotes power or ground. Signals are listed in the following order: RS232
followed by RS485/RS422
Keyboard/Mouse Interfaces
Keyboard Interface
The Super I/O chip (W83627HF) provides the signal lines for the PS/2 keyboard through the keyboard
connector (J1A), which is fully PC/AT compatible.
68CTS3*
RX3+
Clear To Send 3 – Indicates external serial communications device is
ready to receive data. Used as hardware handshake with RTS3 for
low level flow control.
RX3+ – If in RS485 or RS422 mode, this pin is Receive Data 3 -.
7 4 DTR3* Data Terminal Ready 3 – Indicates Serial port 3 is powered,
initialized, and ready. Used as hardware handshake with DSR3 for
overall readiness to communicate.
8 9 RI3* Ring Indicator 3 – Indicates external serial communications device is
detecting a ring condition. Used by software to initiate operations to
answer and open the communications channel.
95
GND Ground
10 NC NC Not connected
11 1
(COM4)
DCD4* Data Carrier Detect 4 – Indicates external serial communications
device is detecting a carrier signal (i.e., a communication channel is
currently open). In direct connect environments, this input will be
driven by DTR4 as part of the DTR4/DSR4 handshake.
12 6 DSR4* Data Set Ready 4 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with
DTR4 for overall readiness to communicate.
13 2 RXD4
RX4-
Receive Data 4 – Serial port 4 receive data in
RX4- – If in RS485 or RS422 mode, this pin is Receive Data 4 -.
14 7 RTS4*
TX4+
Request To Send 4 – Indicates Serial port 4 is ready to transmit data.
Used as hardware handshake with CTS4 for low level flow control.
TX4+ – If in RS485 or RS422 mode, this pin is Transmit Data 4 +.
15 3 TXD4
TX4-
Transmit Data 4 – Serial port 4 transmit data out
TX4- – If in RS485 or RS422 mode, this pin is Transmit Data 4 -.
16 8 CTS4*
RX4+
Clear To Send 4 – Indicates external serial communications device is
ready to receive data. Used as hardware handshake with RTS4 for
low level flow control.
RX4+ – If in RS485 or RS422 mode, this pin is Receive Data 4 +.
17 4 DTR4* Data Terminal Ready 4 – Indicates Serial port 3 is powered,
initialized, and ready. Used as hardware handshake with DSR4 for
overall readiness to communicate.
18 9 NC Not connected
19 5
GND Ground
20 NC NC Not connected
Table 3-5. Serial 3 and 4 (COM3 and COM4) Interface Pin/Signal Descriptions (J15)