User`s manual

User’s Manual 35
5.2 I/O
The RCM2300 was designed to interface with other systems, and so there are no drivers
written specifically for the I/O. The general Dynamic C read and write functions allow
you to customize the parallel I/O to meet your specific needs. For example, use
WrPortI(PEDDR, &PEDDRShadow, 0x00);
to set all the Port E bits as inputs, or use
WrPortI(PEDDR, &PEDDRShadow, 0xFF);
to set all the Port E bits as outputs.
The sample programs in the Dynamic C SAMPLES/RCM2300 directory provide further
examples.
These functions are provided for convenience, not speed. User code should be written in
assembly language when speed is important.
5.2.1 External Interrupts
The Rabbit 2000 microprocessor has four external interrupt inputs on Parallel Port E,
which is accessed through pins PE0, PE1, PE4, and PE5 on header J4. These pins may be
used either as I/O ports or as external interrupt inputs.
Earlier versions of the Rabbit 2000 microprocessor labeled IQ1T or IQ2T would occa-
sionally lose an interrupt request when one of the interrupt inputs was used as a pulse counter.
See Technical Note 301
, Rabbit 2000 Microprocessor Interrupt Problem, for further infor-
mation on how to work around this problem if you purchased your RCM2200 before July,
2002, and the Rabbit 2000 microprocessor is labeled IQ1T or IQ2T.
NOTE: Interrupts on RCM2000 series RabbitCore modules sold after July, 2002, work
correctly and do not need this workaround.
5.3 Serial Communication Drivers
The Prototyping Board has room for an RS-232 chip. Dynamic C has two libraries to sup-
port serial communication: RS232.LIB provides a set of circular-buffer-based functions,
and PACKET.LIB provides packet-based support. Packets can be delimited by time gap,
9th bit detection, or special-character detection.
Both the packet-based and the circular-buffer-based routines are available in blocking and
nonblocking (cofunction) flavors. See the Dynamic C User's Manual and Technical Note
213, Rabbit 2000 Serial Port Software, for more details on serial communication.