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

4.1.1 Memory I/O Interface

The Rabbit 3000 address lines (A0–A18) 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 PB2–PB5 and PB7 can also be used as an auxiliary
address bus.
When using the auxiliary I/O bus for either Ethernet or the LCD/keypad module on the
Prototyping Board, or for any other reason, you must add the following line at the begin-
ning of your program.
#define PORTA_AUX_IO // required to enable auxiliary I/O bus

4.1.2 Other Inputs and Outputs

The status, /RESET_IN, SMODE0, and SMODE1 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 running, 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.
/RES is an output from the reset circuitry that can be used to reset other peripheral devices.
This pin can also be used to reset the microprocessor.
26 RabbitCore RCM3750