Rabbit RabbitCore RCM4000, User Manual

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30 RabbitCore RCM4000
4.2 Serial Communication
The RCM4000 module does not have any serial transceivers directly on the board. How-
ever, a serial interface may be incorporated on the board the RCM4000 is mounted on. For
example, the Prototyping Board has an RS-232 transceiver chip.
4.2.1 Serial Ports
There are five serial ports designated as Serial Ports A, B, C, D, 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 RCM4000 is operating in the Run Mode.
Serial Port B is used by the A/D converter, and is not available for other use off the
RCM4000, but is available on the RCM4010.
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 F can also be configured as an SDLC/HDLC serial port. The IrDA protocol is
also supported in SDLC format by this serial port.
Table 3 summarizes the possible parallel port pins for the serial ports and their clocks.
Table 3. Rabbit 4000 Serial Port and Clock Pins
Serial Port A
TXA PC6, PC7, PD6
Serial Port D
TXD PC0, PC1
RXA PC7, PD7, PE7 RXD PC1, PD1, PE1
SCLKA PB1 SCLKD PD0, PE0, PE3, PC3
Serial Port B
TXB PC4, PC5, PD4
Serial Port F
TXF PD6, PE6, PC6
RXB PC5, PD5, PE5 RXF PD3, PE3, PC3
SCLKB PB0 RCLKF PD1, PE1, PC1
Serial Port C
TXC PC2, PC3 TCLKF PD0, PE0, PC0
RXC PC3, PD3, PE3 TCLKF PD0, PE0, PC0
SCLKC PD2, PE2, PE7, PC7
RCLKF must be selected to be on the same parallel port as TXF.