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CN6 – Serial Connector
GPS COM2 can be directed to either the on-board UART or this serial connector.
Pin RS-232 Name
RS-232 Description
RS-422 Name
RS-422 Description
1 DCD
Carrier
Detect
-
Reserved
2
DSR
Data Set Ready
-
Reserved
3
RxD
Receive Data
RxD-
Receive Data (-)
4
RTS
Request To Send
TxD+
Transmit Data (+)
5
TxD
Transmit Data
TxD-
Transmit Data (-)
6
CTS
Clear To Send
RxD+
Receive Data (+)
7
DTR
Data Terminal Ready
-
Reserved
8 RI
Ring
Indicator
-
Reserved
9 GND
Ground
GND
Ground
10 GND
Ground
GND
Ground
Note on using RS-422 or RS-485 Mode
When using the serial port in RS-422 or RS-485 mode, the serial transmitters are enabled and
disabled under software control. The transmitters are enabled by manipulating the Request To
Send (RTS*) signal of the first serial port controller. This signal is controlled by writing bit 1 of the
Modem Control Register (MCR) as follows:
•
If MCR bit 1 = 1, then RTS* = 0, and serial transmitters are disabled
•
If MCR bit 1 = 0, then RTS* = 1, and serial transmitters are enabled
For more information on the serial port registers, including the MCR, please refer to a standard
PC-AT hardware reference for the 16550-type UART.
