Appendix B. Prototyping Board

Appendix B describes the features and accessories of the Prototyping Board, and explains the use of the Prototyping Board to demonstrate the RCM2200 and to build prototypes of your own circuits.

B.1 Mechanical Dimensions and Layout

Figure B-1 shows the mechanical dimensions and layout for the RCM2200 Prototyping Board.

Figure B-1. RCM2200 Prototyping Board Dimensions

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

Table B-1. RCM2200 Prototyping Board Specifications

Parameter	Specification
Board Size	4.25" × 5.25" × 1.00" (108 mm × 133 mm × 25 mm)
Operating Temperature	-40°C to +70°C
Humidity	5% to 95%, noncondensing
Input Voltage	7.5 V to 25 V DC
Maximum Current Draw (including user-added circuits)	1 A at 12 V and 25°C, 0.7 A at 12 V and 70ºC
Prototyping Area	2.4" × 4.0" (61 mm × 102 mm) throughhole, 0.1" spacing, additional space for SMT components
Standoffs/Spacers	4, accept 6-32 × 3/8 screws

B.2 Power Supply

The RCM2200 requires a regulated 5 V ± 0.25 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 7805 or equivalent linear regulator that is easy to use. Its major drawback is its inefficiency, which is directly proportional to the voltage drop across it. The voltage drop creates heat and wastes power.

A switching power supply may be used in applications where better efficiency is desirable. The LM2575 is an example of an easy-to-use switcher. This part greatly reduces the heat dissipation of the regulator. The drawback in using a switcher is the increased cost.

The Prototyping Board itself is protected against reverse polarity by a Shottky diode at D2 as shown in Figure B-2.

Figure B-2. Prototyping Board Power Supply

B.3 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 to demonstrate the functionality of the RCM2200 right out of the box without any modifications to either board. There are no jumpers or dip switches to configure or misconfigure on the Prototyping Board so that the initial setup is very straightforward.

The Prototyping Board comes with the basic components necessary to demonstrate the operation of the RCM2200. Two LEDs (DS2 and DS3) are connected to PE1 and PE7, and two switches (S2 and S3) are connected to PB2 and PB3 to demonstrate the interface to the Rabbit 2000 microprocessor. Reset switch S1 is the hardware reset for the RCM2200.

To maximize the availability of RCM2200 resources, the demonstration hardware (LEDs and switches) on the Prototyping Board may be disconnected. This is done by cutting the traces below the silk-screen outline of header JP1 on the bottom side of the Prototyping Board. Figure B-3 shows the four places where cuts should be made. Cut the traces between the rows as shown. An exacto knife would work nicely to cut the traces. Alternatively, a small standard screwdriver may be carefully and forcefully used to wipe through the PCB traces.

Figure B-3. Where to Cut Traces to Permanently Disable
Demonstration Hardware on Prototyping Board

The power LED (PWR) and the RESET switch remain connected. Jumpers across the appropriate pins on header JP1 can be used to reconnect specific demonstration hardware later if needed.

Table B-2. Prototyping Board Jumper Settings

Header JP1
Pins	Description
1-2	PE1 to LED DS2
3-4	PE7 to LED DS3
5-6	PB2 to Switch S2
7-8	PB3 to Switch S3

Note that the pinout at location JP1 on the bottom side of the Prototyping Board (shown in Figure B-3) is a mirror image of the top-side pinout.

The Prototyping Board provides the user with RCM2200 connection points brought out conveniently to labeled points at headers J7 and J8 on the Prototyping Board. Small to medium circuits can be prototyped using point-to-point wiring with 20 to 30 AWG wire between the prototyping area and the holes at locations J7 and J8. The holes are spaced at 0.1" (2.5 mm), and 40-pin headers or sockets may be installed at J7 and J8. The pinouts for locations J7 and J8, which correspond to headers J1 and J2, are shown in Figure B-4.

Figure B-4. RCM2200 Prototyping Board Pinout
(Top View)

The small holes are also provided for surface-mounted components that may be installed to the right of the prototyping area.

There is a 2.4" × 4" through-hole prototyping space available on the Prototyping Board. VCC and GND traces run along the edge of the Prototyping Board for easy access. A GND pad is also provided at the lower right for alligator clips or probes.

Figure B-5. VCC and GND Traces Along Edge of Prototyping Board

B.3.1 Adding Other Components

There is room on the Prototyping Board for a user-supplied RS-232 transceiver chip at location U2 and a 10-pin header for serial interfacing to external devices at location J6. A Maxim MAX232 transceiver is recommended. When adding the MAX232 transceiver at position U2, you must also add 100 nF charge storage capacitors at positions C3-C7 as shown in Figure B-6.

Figure B-6. Location for User-Supplied RS-232 Transceiver
and Charge Storage Capacitors on Back Side of Prototyping Board

NOTE	The board that is supplied with the DeviceMate Development Kit already has the RS-232 chip and the storage capacitors installed, and is called the DeviceMate Demonstration Board.

There are two sets of pads that can be used for surface mount prototyping SOIC devices. The silk screen layout separates the rows into six 16-pin devices (three on each side). However, there are pads between the silk screen layouts giving the user two 52-pin (2× 26) SOIC layouts with 50 mil pin spacing. There are six sets of pads that can be used for 3- to 6-pin SOT23 packages. There are also 60 sets of 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.

There is also a space above the space for the RS-232 transceiver that can accommodate a large surface-mounted SOIC component.

B.3.2 Attach Modules to Prototyping Board

Turn the RCM2200 module so that the Ethernet connector end of the module extends to the right, as shown in Figure B-7 below. Align the module headers J4 and J5 into sockets J1 and J2 (the MASTER slots) on the Prototyping Board. Press the module's pins firmly into the Prototyping Board headers.

Figure B-7. Install the RCM2200 on the Prototyping Board

NOTE

It is important that you line up the pins of the module headers exactly with the corresponding pins on the Prototyping Board. The header pins may become bent or damaged if the pin alignment is offset, and the module will not work. Permanent electrical damage to the module may also result if a misaligned module is powered up.

With the RCM2200 plugged into the MASTER slots, it has full access to the RS-232 transceiver, and can act as the "master" relative to another RabbitCore RCM2200 or RCM2300 plugged into the SLAVE slots, which acts as the "slave."

This master/slave relationship is not used in the DeviceMate Development Kit where the "target" RCM2300 is plugged into the MASTER slots, and the RCM2200, which is used as the DeviceMate hardware platform, is plugged into the SLAVE slots. The special Demonstration Board serves only as a means to connect the two RabbitCore modules together to demonstrate the DeviceMate software features in Dynamic C Premier.