Z-World RabbitCore RCM3200, Руководство пользователя

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User’s Manual 11
2.1.1 Memory I/O Interface
The Rabbit 3000 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.
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 PB3–PB7 can also be used as an external address bus.
When using the auxiliary I/O bus, you must add the following line at the beginning of
your program.
#define PORTA_AUX_IO // required to enable auxiliary I/O bus
The STATUS output has three different programmable functions:
1. It can be driven low on the first op code fetch cycle.
2. It can be driven low during an interrupt acknowledge cycle.
3. It can also serve as a general-purpose output.
2.1.2 Other Inputs and Outputs
Two status mode pins, SMODE0 and SMODE1, are available as inputs. The logic state of
these two pins determines the startup procedure after a reset.
/RESET_IN is an external input used to reset the Rabbit 3000 microprocessor and the
RCM3200 memory. /RES is an output from the reset circuitry that can be used to reset
other peripheral devices.