Rabbit RabbitCore RCM2200, User Manual

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User’s Manual 33
5.2 I/O
The RCM2200 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\RCM2200
directory provide further
examples.
5.2.1 PCLK Output
The PCLK output is controlled by bits 7 and 6 of the Global Output Register (GOCR) on
the Rabbit 2000 microprocessor, and so can be enabled or disabled in software. Starting
with Dynamic C v 7.02, the PCLK output is disabled by default at compile time to mini-
mize radiated emissions; the PCLK output is enabled in earlier versions of Dynamic C.
Use the following code to set the PCLK output as needed.
PCLK output driven with peripheral clock:
WrPortI(GOCR, &GOCRShadow, (GOCRShadow&~0xc0));
PCLK output driven with peripheral clock ÷ 2:
WrPortI(GOCR, &GOCRShadow, ((GOCRShadow&~0xc0)| 0x40));
PCLK output off (low):
WrPortI(GOCR, &GOCRShadow, ((GOCRShadow&~0xc0)| 0x80));
PCLK output on (high):
WrPortI(GOCR, &GOCRShadow, (GOCRShadow | 0xc0));
5.2.2 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.