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Table 2. RCM4200 Pinout Configurations (continued)
Pin
Pin Name
46
PD6
47
PD7
48
CONVERT
49
VREF
50
GND
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
RCM4200.
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
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 PE5–PE7 pins can be brought out to header J2 instead of the STATUS and the two
SMODE pins, SMODE0 and SMODE1, 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 RCM4200 memory.
/RESET_OUT is an output from the reset circuitry that can be used to reset other
peripheral devices.
34
Default Use
I/O Strobe I6
D14
Input/Output
PWM2
TXA/TXE
IA7
I/O Strobe I7
D15
Input/Output
PWM3
RXA/RXE
Input Capture
Digital Input
Analog reference
voltage
Ground
// required to enable auxiliary I/O bus
Alternate Use
Serial Port E
(RCM4210 only)
A/D converter
(RCM4200 only)
1.15 V/2.048 V/2.500 V
on-chip ref. voltage
(RCM4200 only)
Analog ground
Notes
RabbitCore RCM4200
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