Appendix B. Prototyping Board

RabbitCore RCM3900
User's Manual

Appendix B. Prototyping Board

Appendix B describes the features and accessories of the Prototyping Board.

B.1 Introduction

The Prototyping Board included in the Development Kit makes it easy to connect an RCM3900 module to a power supply and a PC workstation for development. It also provides some basic I/O peripherals (RS-232, RS-485, a relay, LEDs, and switches), as well as a prototyping area for more advanced hardware development.

For the most basic level of evaluation and development, the Prototyping Board can be used without modification.

As you progress to more sophisticated experimentation and hardware development, modifications and additions can be made to the board without modifying or damaging the RCM3900 module itself.

The Prototyping Board is shown below in Figure B-1, with its main features identified.

Figure B-1. Prototyping Board

B.1.1 Prototyping Board Features

Power Connection—A power-supply jack and a 3-pin header are provided for connection to the power supply. Note that the 3-pin header is symmetrical, with both outer pins connected to ground and the center pin connected to the raw V+ input. The cable of the AC adapter provided with Development Kit ends in a 3-pin plug that connects to the 3-pin header (J2)—the center pin of J2 is always connected to the positive terminal, and either edge pin is negative.

Users providing their own power supply should ensure that it delivers 8–30 V DC at 1 A.

Regulated Power Supply—The raw DC voltage provided at the POWER IN jack is routed to a 5 V switching voltage regulator, then to a separate 3.3 V linear regulator. The regulators provide stable power to the RCM3900 module and the Prototyping Board. The voltage regulators will get warm while in use.

Power LED—The power LED lights whenever power is connected to the Prototyping Board.

Core LED—The core LED lights whenever an RCM3900 module is plugged in correctly on the Prototyping Board and the RCM3900 module is not being reset.

Relay LED—The relay LED lights whenever the Prototyping Board relay is energized.

Reset Switch—A momentary-contact, normally open switch is connected directly to the RCM3900's /RESET_IN pin. Pressing the switch forces a hardware reset of the system.

I/O Switches and LEDs—Two momentary-contact, normally open switches are connected to the PG0 and PG1 pins of the RCM3900 module and may be read as inputs by sample applications.

Four user LEDs (DS3–DS6) are connected to alternate I/O bus pins PA0–PA3 pins of the RCM3900 module via U8, and may be driven as output indicators. PE7 and PG5 control the registers in U8 as shown in the sample applications.

Prototyping Area—A generous prototyping area has been provided for the installation of through-hole components. +3.3 V, +5 V, and Ground buses run along one edge of this area. Several areas for surface-mount devices are also available. Each SMT pad is connected to a hole designed to accept a 30 AWG solid wire.

LCD/Keypad Module—Rabbit's LCD/keypad module may be plugged in directly to headers LCD1JA, LCD1JB, and LCD1JC. The signals on headers LCD1JB and LCD1JC will be available only if the LCD/keypad module is plugged in to header LCD1JA. Appendix C provides complete information for mounting and using the LCD/keypad module.

Module Extension Headers—The complete pin set of the RCM3900 module is duplicated at headers J8 and J9. Developers can solder wires directly into the appropriate holes, or, for more flexible development, 2 × 17 header strips with a 0.1" pitch can be soldered into place. See Figure B-4 for the header pinouts.

Digital I/O—Four digital inputs are available on screw-terminal header J6. See Figure B-4 for the header pinouts.

RS-232—Two 3-wire serial ports or one 5-wire RS-232 serial port are available on the Prototyping Board at screw-terminal header J14.

RS-485—One RS-485 serial port is available on the Prototyping Board at screw-terminal header J14.

Quadrature Decoder—Four quadrature decoder inputs (PF0–PF3) from the Rabbit 3000 chip are available on screw-terminal header J5. See Figure B-4 for the header pinouts.

H-Bridge Motor Driver—Two pairs of H-bridge motor drivers are supported using screw-terminal headers J3 and J4 on the Prototyping Board for stepper-motor control. See Figure B-4 for the header pinouts.

RabbitNet Port—One RS-422 RabbitNet port (shared with the serial flash interface) is available to allow RabbitNet peripheral cards to be used with the Prototyping Board. The Prototyping Board cannot be used with RabbitNet peripheral cards when the RCM3900/RCM3910 is installed.

Serial Flash Interface—One serial flash interface (shared with the RabbitNet port) is available to allow Rabbit's SF1000 series serial flash to be used on the Prototyping Board. The Prototyping Board cannot be used with the SF1000 series of serial flash memories when the RCM3900/RCM3910 is installed.

B.2 Mechanical Dimensions and Layout

Figure B-2 shows the mechanical dimensions and layout for the Prototyping Board.

Figure B-2. Prototyping Board Dimensions
NOTE All measurements are in inches followed by millimeters enclosed in parentheses.

Table B-1 lists the electrical, mechanical, and environmental specifications for the Prototyping Board.

Table B-1. Prototyping Board Specifications
Parameter Specification

Board Size
5.25" × 6.75" × 1.00" (133 mm × 171 mm × 25 mm)

Operating Temperature
–20°C to +70°C

Humidity
5% to 95%, noncondensing

Input Voltage
8 V to 30 V DC

Maximum Current Draw
(including user-added circuits)
800 mA max. for +3.3 V supply,
1 A total +3.3 V and +5 V combined

Backup Battery
CR2032, 3 V lithium coin-type

Digital Inputs

4 inputs pulled up, ± 36 V DC,
switching threshold 0.9–2.3 V typical

Digital Outputs

4 sinking outputs,+30 V DC, 500 mA maximum per channel
8 CMOS-level outputs if stepper motor not installed

Relay
SPDT relay, 500 mA @ 30 V

Serial Ports

two 3-wire RS-232 or one RS-232 with RTS/CTS

one RS-485

Other Serial Interfaces
RabbitNet RS-422 port or serial flash interface¹

Other Interfaces

stepper motor control

quadrature decoder

LCD/keypad module

LEDs
Seven LEDs

one power on indicator

one RCM3900 module indicator

four user-configurable LEDs

one relay indicator

Prototyping Area
Throughhole, 0.1" spacing, additional space for SMT components

Connectors

two 2 × 17, 2 mm pitch sockets for RCM3900 module

one 2 × 5, 2 mm pitch socket for serial flash^*

six screw-terminal headers for serial ports, digital inputs, stepper motor control, quadrature decoder, and relay contacts

one RJ-45 RabbitNet jack^*

Standoffs/Spacers
7, accept 4-40 x 1/2 screws

¹ This interface is not available when the RCM3900/RCM3910 is installed.

B.3 Power Supply

The RCM3900 requires a regulated 3.15 V to 3.45 V DC power source to operate. Depending on the amount of current required by the application, different regulators can be used to supply this voltage.

The Prototyping Board has an onboard +5 V switching power regulator from which a +3.3 V linear regulator draws its supply. Thus both +5 V and +3.3 V are available on the Prototyping Board.

The Prototyping Board itself is protected against reverse polarity by a diode at D1 as shown in Figure B-3.

Figure B-3. Prototyping Board Power Supply

B.4 Using the Prototyping Board

The Prototyping Board is actually both a demonstration board and a prototyping board. As a demonstration board, it can be used with the sample programs to demonstrate the functionality of the RCM3900 right out of the box without any modifications.

The Prototyping Board pinouts are shown in Figure B-4.

Figure B-4. Prototyping Board Pinout

The Prototyping Board comes with the basic components necessary to demonstrate the operation of the RCM3900. Four user LEDs (DS3–DS6) are connected to alternate I/O bus pins PA0–PA3 pins of the RCM3900 module via U8, and may be driven as output indicators when controlled by PE7 and PG5 as shown in the sample applications. Two switches (S2 and S3) are connected to PG0 and PG1 to demonstrate the interface to the Rabbit 3000 microprocessor. Reset switch S1 is the hardware reset for the RCM3900.

The Prototyping Board provides the user with RCM3900 connection points brought out conveniently to labeled points at J8 and J9 on the Prototyping Board. Although locations J8 and J9 are unstuffed, 2 × 17 headers are included in the bag of parts.

RS-232 and RS-485 signals are available on screw-terminal header J14, quadrature decoder inputs are available on screw-terminal header J5, and digital inputs are available on screw-terminal header J6. A 1 × 5 header strip from the bag of parts may be installed at J12 for four sinking digital outputs. The clocked Serial Port B signals from the RCM3900 are used for the miniSD™ Card, and cannot be accessed via header J13 on the Prototyping Board.

If you don't plan to use the LCD/keypad module, additional signals may be brought out on 1 × 5 and 1 × 8 headers from the bag of parts that you install at J15 and J16. If you don't plan to use the stepper-motor control option, additional CMOS outputs are available via a 1 × 8 header that you install at J10.

There is a through-hole prototyping space available on the Prototyping Board. The holes in the prototyping area are spaced at 0.1" (2.5 mm). +3.3 V, +5 V, and GND traces run along one edges of the prototyping area. Small to medium circuits can be prototyped using point-to-point wiring with 20 to 30 AWG wire between the prototyping area, the +3.3 V, +5 V, and GND traces, and the surrounding area where surface-mount components may be installed. Small holes are provided around the surface-mounted components that may be installed around the prototyping area.

B.4.1 Adding Other Components

There are two sets of pads for 6-pin, 16-pin, and 28-pin devices that can be used for surface-mount prototyping devices. There are also pads that can be used for SMT resistors and capacitors in an 0805 SMT package. Each component has every one of its pin pads connected to a hole in which a 30 AWG wire can be soldered (standard wire wrap wire can be soldered in for point-to-point wiring on the Prototyping Board). Because the traces are very thin, carefully determine which set of holes is connected to which surface-mount pad.

B.4.2 Digital I/O

B.4.2.1 Digital Inputs

The Prototyping Board has four digital inputs, IN0–IN3, each of which is protected over a range of –36 V to +36 V. The inputs are pulled up to +3.3 V as shown in Figure B-5.

Figure B-5. Prototyping Board Digital Inputs

The four quadrature decoder inputs on screw-terminal header J5 may be used as inputs IN4–IN7. To use the PF0 signal from the Rabbit microprocessor, which goes to QD1B, remember to reconfigure the jumper on header JP3 to jumper pins 1–2.

The actual switching threshold is between 0.9 V and 2.3 V. Anything below this value is a logic 0, and anything above is a logic 1.

The digital inputs are each fully protected over a range of -36 V to +36 V, and can handle short spikes of ±40 V.

B.4.3 CMOS Digital Outputs

If the stepper-motor option is not used, eight CMOS-level digital outputs are available at J10, and can each handle up to 25 mA.

B.4.4 Sinking Digital Outputs

Four sinking digital outputs shared with LEDs DS3–DS6 are available at J12, and can each handle up to 500 mA. Figure B-6 shows a wiring diagram for a typical sinking output.

Figure B-6. Prototyping Board Sinking Digital Outputs

B.4.5 Relay Outputs

Figure B-7 shows the contact connections for the relay on the Prototyping Board. A diode across the coil provides a return path for inductive spikes, and snubbers across the relay contacts protect the relay contacts from inductive spikes.

Figure B-7. Prototyping Board Relay Output Contact Connections

The relay is driven by pin PA4 of the RCM3900 module via U8, and is controlled by PE7 and PG5 as shown in the sample applications.

B.4.6 Serial Communication

The Prototyping Board allows you to access up to three of the serial ports from the RCM3900/RCM3910. Table B-2 summarizes the configuration options.

Table B-2. Prototyping Board Serial Port Configurations
Serial Port Signal Header Configured via Default Use Alternate Use

C

J14

JP5¹

RS-485

—

D

J7

JP3

RabbitNet/SF1000 interface²

Rabbit 3000
quadrature decoder

J11

E

J14

—

RS-232

—

F

J14

—

RS-232

—

¹ RS-485 termination and bias resistors are configured via header JP5.

² This interface is not available when the RCM3900/RCM3910 is installed.

Ordinarily, Serial Port D must be configured either to allow J7 to be used as a RabbitNet port or to allow J11 to be used as a serial interface for the SF1000 series serial flash. When other RabbitCore modules supplied with this Prototyping Board in their Development Kit are plugged into the Prototyping Board, PD2 is configured in software to enable the RS-422 transceiver for the RabbitNet SPI interface. PD2 is not brought out from the RCM3900/RCM3910. Serial Port D may be used as a serial port via the Prototyping Board when the RCM3900/RCM3910 is installed with PC0 and PC1 to a serial transceiver of your own in the prototyping area.

B.4.6.1 RS-232

RS-232 serial communication on the Prototyping Board is supported by an RS-232 transceiver installed at U9. This transceiver provides the voltage output, slew rate, and input voltage immunity required to meet the RS-232 serial communication protocol. Basically, the chip translates the Rabbit 3000's signals to RS-232 signal levels. Note that the polarity is reversed in an RS-232 circuit so that a +5 V output becomes approximately -10 V and 0 V is output as +10 V. The RS-232 transceiver also provides the proper line loading for reliable communication.

RS-232 can be used effectively at the RCM3900 module's maximum baud rate for distances of up to 15 m.

RS-232 flow control on an RS-232 port is initiated in software using the serXflowcontrolOn() function call from the LIB\RS232.LIB, where X is the serial port (E or F). The locations of the flow control lines are specified using a set of five macros.

SERX_RTS_PORT—Data register for the parallel port that the RTS line is on (e.g., PGDR).

SERX_RTS_SHADOW—Shadow register for the RTS line's parallel port (e.g., PGDRShadow).

SERX_RTS_BIT—The bit number for the RTS line.

SERX_CTS_PORT—Data register for the parallel port that the CTS line is on (e.g., PCDRShadow).

SERX_CTS_BIT—The bit number for the CTS line.

Standard 3-wire RS-232 communication using Serial Ports E and F is illustrated in the following sample code.
#define EINBUFSIZE  15   // set size of circular buffers in bytes
#define EOUTBUFSIZE 15
#define FINBUFSIZE  15
#define FOUTBUFSIZE 15
#define MYBAUD 115200   // set baud rate
#endif
main(){
    serEopen(_MYBAUD);   // open Serial Ports E and F
    serFopen(_MYBAUD);
    serEwrFlush();       // flush their input and transmit buffers
    serErdFlush();
    serFwrFlush();
    serFrdFlush();
    serEclose(_MYBAUD);  // close Serial Ports C and D
    serFclose(_MYBAUD);
}
B.4.6.2 RS-485

The Prototyping Board has one RS-485 serial channel, which is connected to the Rabbit 3000 Serial Port C through an RS-485 transceiver. The half-duplex communication uses an output from PD7 on the Rabbit 3000 to control the transmit enable on the communication line. Using this scheme a strict master/slave relationship must exist between devices to insure that no two devices attempt to drive the bus simultaneously.

Serial Port C is configured in software for RS-485 as follows.
#define ser485open serCopen
#define ser485close serCclose
#define ser485wrFlush serCwrFlush
#define ser485rdFlush serCrdFlush
#define ser485putc serCputc
#define ser485getc serCgetc
#define CINBUFSIZE  15
#define COUTBUFSIZE 15
#ifndef _485BAUD
#define _485BAUD 115200
#endif
The configuration shown above is based on circular buffers. RS-485 configuration may also be done using functions from the LIB\PACKET.LIB library.

The Prototyping Boards with RCM3900 modules installed can be used in an RS-485 multidrop network spanning up to 1200 m (4000 ft), and there can be as many as 32 attached devices. Connect the 485+ to 485+ and 485– to 485– using single twisted-pair wires as shown in Figure B-8. Note that a common ground is recommended.

Figure B-8. Multidrop Network

The Prototyping Board comes with a 220 W termination resistor and two 681 W bias resistors installed and enabled with jumpers across pins 1–2 and 5–6 on header JP5, as shown in Figure B-9.

Figure B-9. RS-485 Termination and Bias Resistors

For best performance, the termination resistors in a multidrop network should be enabled only on the end nodes of the network, but not on the intervening nodes. Jumpers on boards whose termination resistors are not enabled may be stored across pins 1–3 and 4–6 of header JP5.

B.4.7 RabbitNet Port

The RJ-45 jack labeled RabbitNet is a clocked SPI RS-422 serial I/O expansion port for use with RabbitNet peripheral boards. The RabbitNet port is unavailable when an RCM3900/RCM3910 is in place on the Prototyping Board.

B.4.8 Other Prototyping Board Modules

An optional LCD/keypad module is available that can be mounted on the Prototyping Board. The signals on headers LCD1JB and LCD1JC will be available only if the LCD/keypad module is installed. Refer to Appendix C, "LCD/Keypad Module," for complete information.

B.4.9 Quadrature Decoder

Four quadrature decoder inputs are available on screw-terminal header J5. To use the PF0 input from the Rabbit microprocessor, which goes to the QD1B input, remember to reconfigure the jumper on header JP3 to jumper pins 1–2.

Additional information on the use of the quadrature decoders on Parallel Port F is provided in the Rabbit 3000 Microprocessor User's Manual.

B.4.10 Stepper-Motor Control

The Prototyping Board can be used to demonstrate the use of the RCM3900 to control a stepper motor. Stepper motor control typically directs moves in two orthogonal directions, and so two sets of stepper-motor control circuits are provided for via screw-terminal headers J3 and J4.

In order to use the stepper-motor control, install two Texas Instruments L293DN chips at locations U2 and U3 (shown in Figure B-10). These chips are readily available from your favorite electronics parts source, and may be purchased through our Web store as part number 660-0205.

Figure B-10. Install Four-Channel Push-Pull Driver Chips

Figure B-11 shows the stepper-motor driver circuit.

Figure B-11. Stepper-Motor Driver Circuit

The stepper motor(s) can be powered either from the onboard power supply or from an external power based on the jumper settings on headers JP1 and JP2.

Table B-3. Stepper Motor Power-Supply Options
Header Pins Connected Factory Default

JP1

1–2
9–10

Onboard power supply to U2

×

3–4
7–8

External power supply to U2

JP2

1–2
9–10

Onboard power supply to U3

×

3–4
7–8

External power supply to U3

B.5 Prototyping Board Jumper Configurations

Figure B-12 shows the header locations used to configure the various Prototyping Board options via jumpers.

Figure B-12. Location of Prototyping Board Configurable Positions

Table B-4 lists the configuration options using jumpers.

Table B-4. Prototyping Board Jumper Configurations
Header Description Pins Connected Factory Default

JP1

Stepper Motor Power-Supply Options (U2)

1–2
9–10

Onboard power supply

×

3–4
7–8

External power supply

JP2

Stepper Motor Power-Supply Options (U3)

1–2
9–10

Onboard power supply

×

3–4
7–8

External power supply

JP3

PF0 Option

1–2

Quadrature decoder inputs enabled

2–3

RabbitNet/Serial Flash interface enabled

×

JP4

RCM3900 Power Supply

2–3

RCM3900 powered via Prototyping Board

×

JP5

RS-485 Bias and Termination Resistors

1–2
5–6

Bias and termination resistors connected

×

1–3
4–6

Bias and termination resistors not connected (parking position for jumpers)

B.6 Use of Rabbit 3000 Parallel Ports

Table B-5 lists the Rabbit 3000 parallel ports and their use for the Prototyping Board.

Table B-5. Prototyping Board Use of Rabbit 3000 Parallel Ports
Port I/O Use Initial State

PA0–PA3

Data Bus

LCD/keypad module, motor driver, LEDs

Active high

PA4

Data Bus

LCD/keypad module, motor driver,
relay and relay LED

Active high

PA5–PA7

Data Bus

LCD/keypad module, motor control

Active high

PB0

Input

CLKB, miniSD™ Card

High

PB1

Input

CLKA, Programming Port

High
(when not driven by CLKA)

PB2–PB5

Address Bus

LCD/keypad module

High

PB6–PB7

Address Bus

—

High

PC0

Output

TXD
Serial Port D

High (disabled)

PC1

Input

RXD

High (disabled)

PC2

Output

TXC RS-485
Serial Port C

High (RS-485 disabled)

PC3

Input

RXC RS-485

High (RS-485 disabled)

PC4

Output

TXB, miniSD™ Card
Serial Port B¹

High (disabled)

PC5

Input

RXB, miniSD™ Card

High (disabled)

PC6

Output

TXA, Programming Port
Serial Port A

High

PC7

Input

RXA, Programming Port

High

PD0²

Output

RCM3900 BSY LED off
(shared with NAND flash busy)

High

PD1

Output

NAND flash chip enable

High (disabled)

PD2³

Input

miniSD™ Card card detect on RCM3900/RCM3910

High when miniSD™ Card is installed

PD3

Output

—

High (SPI CS disabled)

PD4–PD6

Input

—

High (disabled)

PD7

Output

RS-485 Tx enable

Low (RS-485 Tx disabled)

PE0–PE1

Input

IN0–IN1, J6

High

PE2

Output

Ethernet AEN,
NAND flash function enable

High (disabled)

PE3

Output

Motor driver A clock pulse

Low (disabled)

PE4–PE5

Input

IN2–IN3, J6

High

PE6

Output

LCD/keypad module

High (disabled)

PE7

Output

Motor driver B clock pulse

High (disabled)

PF0

Input

Quadrature decoder

High

PF1–PF3

Input

Quadrature decoder

High

PF4–PF7

Output

Motor 1–4 control

Low (disabled)

PG0

Input

Switch S1

High

PG1

Input

Switch S2

High

PG2

Input

TXF RS-232
Serial Port F

High (RS-232 disabled)

PG3

Input

RXF RS-232

High (RS-232 disabled)

PG4

Output

Motor driver A enable

High (disabled)

PG5

Output

Motor driver B enable

High (disabled)

PG6

Input

TXE RS-232
Serial Port E

High (RS-232 disabled)

PG7

Input

RXE RS-232

High (RS-232 disabled)

¹ Serial Port B is not available on the Prototyping Board when the RCM3900/RCM3910 is plugged in.

² PD0, PD1, and PE2 are not normally available on the Prototyping Board because they are not brought out on RCM3900 header J61.

³ PD2 is not brought out to the Prototyping Board when the RCM3900/RCM3910 RabbitCore modules are installed.

***Table B-1. Prototyping Board Specifications***
Parameter	Specification
Board Size	5.25" × 6.75" × 1.00" (133 mm × 171 mm × 25 mm)
Operating Temperature	–20°C to +70°C
Humidity	5% to 95%, noncondensing
Input Voltage	8 V to 30 V DC
Maximum Current Draw (including user-added circuits)	800 mA max. for +3.3 V supply, 1 A total +3.3 V and +5 V combined
Backup Battery	CR2032, 3 V lithium coin-type
Digital Inputs	4 inputs pulled up, ± 36 V DC, switching threshold 0.9–2.3 V typical
Digital Outputs	4 sinking outputs,+30 V DC, 500 mA maximum per channel 8 CMOS-level outputs if stepper motor not installed
Relay	SPDT relay, 500 mA @ 30 V
Serial Ports	two 3-wire RS-232 or one RS-232 with RTS/CTS one RS-485
Other Serial Interfaces	RabbitNet RS-422 port or serial flash interface¹
Other Interfaces	stepper motor control quadrature decoder LCD/keypad module
LEDs	Seven LEDs one power on indicator one RCM3900 module indicator four user-configurable LEDs one relay indicator
Prototyping Area	Throughhole, 0.1" spacing, additional space for SMT components
Connectors	two 2 × 17, 2 mm pitch sockets for RCM3900 module one 2 × 5, 2 mm pitch socket for serial flash^* six screw-terminal headers for serial ports, digital inputs, stepper motor control, quadrature decoder, and relay contacts one RJ-45 RabbitNet jack^*
Standoffs/Spacers	7, accept 4-40 x 1/2 screws

***Table B-2. Prototyping Board Serial Port Configurations***
Serial Port	Signal Header	Configured via	Default Use	Alternate Use
C	J14	JP5¹	RS-485	—
D	J7	JP3	RabbitNet/SF1000 interface²	Rabbit 3000 quadrature decoder
J11
E	J14	—	RS-232	—
F	J14	—	RS-232	—

***Table B-3. Stepper Motor Power-Supply Options***
Header	Pins Connected	Factory Default
JP1	1–2 9–10	Onboard power supply to U2	×
3–4 7–8	External power supply to U2
JP2	1–2 9–10	Onboard power supply to U3	×
3–4 7–8	External power supply to U3

***Table B-4. Prototyping Board Jumper Configurations***
Header	Description	Pins Connected	Factory Default
JP1	Stepper Motor Power-Supply Options (U2)	1–2 9–10	Onboard power supply	×
3–4 7–8	External power supply
JP2	Stepper Motor Power-Supply Options (U3)	1–2 9–10	Onboard power supply	×
3–4 7–8	External power supply
JP3	PF0 Option	1–2	Quadrature decoder inputs enabled
2–3	RabbitNet/Serial Flash interface enabled	×
JP4	RCM3900 Power Supply	2–3	RCM3900 powered via Prototyping Board	×
JP5	RS-485 Bias and Termination Resistors	1–2 5–6	Bias and termination resistors connected	×
1–3 4–6	Bias and termination resistors not connected (parking position for jumpers)

***Table B-5. Prototyping Board Use of Rabbit 3000 Parallel Ports***
Port	I/O	Use	Initial State
PA0–PA3	Data Bus	LCD/keypad module, motor driver, LEDs	Active high
PA4	Data Bus	LCD/keypad module, motor driver, relay and relay LED	Active high
PA5–PA7	Data Bus	LCD/keypad module, motor control	Active high
PB0	Input	CLKB, miniSD™ Card	High
PB1	Input	CLKA, Programming Port	High (when not driven by CLKA)
PB2–PB5	Address Bus	LCD/keypad module	High
PB6–PB7	Address Bus	—	High
PC0	Output	TXD	Serial Port D	High (disabled)
PC1	Input	RXD	High (disabled)
PC2	Output	TXC RS-485	Serial Port C	High (RS-485 disabled)
PC3	Input	RXC RS-485	High (RS-485 disabled)
PC4	Output	TXB, miniSD™ Card	Serial Port B¹	High (disabled)
PC5	Input	RXB, miniSD™ Card	High (disabled)
PC6	Output	TXA, Programming Port	Serial Port A	High
PC7	Input	RXA, Programming Port	High
PD0²	Output	RCM3900 BSY LED off (shared with NAND flash busy)	High
PD1	Output	NAND flash chip enable	High (disabled)
PD2³	Input	miniSD™ Card card detect on RCM3900/RCM3910	High when miniSD™ Card is installed
PD3	Output	—	High (SPI CS disabled)
PD4–PD6	Input	—	High (disabled)
PD7	Output	RS-485 Tx enable	Low (RS-485 Tx disabled)
PE0–PE1	Input	IN0–IN1, J6	High
PE2	Output	Ethernet AEN, NAND flash function enable	High (disabled)
PE3	Output	Motor driver A clock pulse	Low (disabled)
PE4–PE5	Input	IN2–IN3, J6	High
PE6	Output	LCD/keypad module	High (disabled)
PE7	Output	Motor driver B clock pulse	High (disabled)
PF0	Input	Quadrature decoder	High
PF1–PF3	Input	Quadrature decoder	High
PF4–PF7	Output	Motor 1–4 control	Low (disabled)
PG0	Input	Switch S1	High
PG1	Input	Switch S2	High
PG2	Input	TXF RS-232	Serial Port F	High (RS-232 disabled)
PG3	Input	RXF RS-232	High (RS-232 disabled)
PG4	Output	Motor driver A enable	High (disabled)
PG5	Output	Motor driver B enable	High (disabled)
PG6	Input	TXE RS-232	Serial Port E	High (RS-232 disabled)
PG7	Input	RXE RS-232	High (RS-232 disabled)

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