Rabbit RabbitCore RCM4400W, Руководство по эксплуатации продукта

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OEM User’s Manual 33
4.1.1 Memory I/O Interface
The Rabbit 4000 address lines (A0–A19) and all the data lines (D0–D7) are routed inter-
nally to the onboard flash memory and SRAM chips. I/0 write (/IOWR) and I/0 read (/
IORD) are available for interfacing to external devices, and are also used by the
RCM4400W.
Parallel Port A can also be used as an external I/O data bus to isolate external I/O from the
main data bus. Parallel Port B pins PB2–PB7 can also be used as an auxiliary address bus.
When using the auxiliary I/O bus for any reason, you must add the following line at the
beginning of your program.
#define PORTA_AUX_IO // required to enable auxiliary I/O bus
Selected pins on Parallel Ports D and E as specified in Table 2 may be used for input
capture, quadrature decoder, DMA, and pulse-width modulator purposes.
4.1.2 Other Inputs and Outputs
The STATUS pin can be brought out to header J1 instead of the PE7 pin as explained in
Appendix A.6.
/RESET_IN is normally associated with the programming port, but may be used as an
external input to reset the Rabbit 4000 microprocessor and the RCM4400W memory.
/RESET_OUT is an output from the reset circuitry that can be used to reset other
peripheral devices.