Memory I/O Interface; Other Inputs And Outputs - Rabbit MiniCore RCM5700 User Manual

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Datasheet of 101-1274 - KIT DEV STANDARD RCM5700
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4.1.1 Memory I/O Interface

The Rabbit 5000 address lines (A0–A19) and data lines (D0–D7) are routed to the onboard flash
memory chip. I/O write (/IOWR) and I/O 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 PB2–PB7 can also be used as an external address bus.
When using the external I/O bus for either Ethernet or the LCD/keypad module on the Prototyp-
ing Board or for any other reason, you must add the following line at the beginning of your pro-
gram.
#define PORTA_AUX_IO
Selected pins on Parallel Ports D and E as specified in Table 4-3 may be used for input capture,
quadrature decoder, DMA, and pulse-width modulator purposes.

4.1.2 Other Inputs and Outputs

The status, /RESET_IN, and SMODE I/O are normally associated with the programming port.
Since the status pin is not used by the system once a program has been downloaded and is run-
ning, the status pin can then be used as a general-purpose CMOS output. The programming port is
described in more detail in Section 4.2.3.
/RESET_IN is an external input used to reset the Rabbit 5000/6000 microprocessor and the Mini-
Core memory. /RESET is an output from the reset circuitry that can be used to reset other periph-
eral devices.
The two SMODE pins, SMODE0 and SMODE1, are tied together, and may be used as a special
input when the MiniCore is operating in the Run Mode. The logic state of these two pins deter-
mines the startup procedure after a reset.
MiniCore RCM5700/RCM6700 User's Manual
// required to enable external I/O bus
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