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4.2 Serial Communication
The RCM3700 board does not have any serial transceivers directly on the board. How-
ever, a serial interface may be incorporated on the board the RCM3700 is mounted on. For
example, the Prototyping Board has RS-232, RS-485 and IrDA transceiver chips.
4.2.1 Serial Ports
There are five serial ports designated as Serial Ports A, C, D, E, and F. All five serial ports
can operate in an asynchronous mode up to the baud rate of the system clock divided by 8.
An asynchronous port can handle 7 or 8 data bits. A 9th bit address scheme, where an
additional bit is sent to mark the first byte of a message, is also supported.
Serial Port A is normally used as a programming port, but may be used either as an asyn-
chronous or as a clocked serial port once application development has been completed and
the RCM3700 is operating in the Run Mode.
Serial Ports C and D can also be operated in the clocked serial mode. In this mode, a clock
line synchronously clocks the data in or out. Either of the two communicating devices can
supply the clock.
Serial Ports E and F can also be configured as HDLC serial ports. The IrDA protocol is
also supported in SDLC format by these two ports.
Serial Port F shares its pins with Serial Ports C and D on header J1, as shown in Figure 7.
The selection of port(s) depends on your need for two clocked serial ports (Serial Ports C
and D) vs. a second HDLC serial port (Serial Port F).
J1: 23
J1: 24
J1: 21
J1: 22
The serial ports used are selected with the
port (C, D, or F). Remember that RxC and RxD on Serial Ports C and D cannot be used if
Serial Port F is being used
RabbitCore RCM3700 User's Manual
TXC
PC2
RXC
PC3
TXD
PC0
RXD
PC1
TXF
PG2
RXF
PG3
Figure 7. RCM3700 Serial Ports C, D, and F
serXOpen
function call, where X is the serial
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