RabbitCore RCM3700 User's Manual

Appendix A. RCM3700 Specifications

Appendix A provides the specifications for the RCM3700, and describes the conformal coating.

A.1 Electrical and Mechanical Characteristics

Figure A-1 shows the mechanical dimensions for the RCM3700.

Figure A-1. RCM3700 Dimensions

NOTE	All measurements are in inches followed by millimeters enclosed in parentheses. All dimensions have a manufacturing tolerance of ±0.01" (0.2 mm).

It is recommended that you allow for an "exclusion zone" of 0.04" (1 mm) around the RCM3700 in all directions when the RCM3700 is incorporated into an assembly that includes other printed circuit boards. An "exclusion zone" of 0.16" (4 mm) is recommended below the RCM3700 when the RCM3700 is plugged into another assembly using the shortest connectors for header J1. Figure A-2 shows this "exclusion zone."

Figure A-2. RCM3700 "Exclusion Zone"

Table A-1 lists the electrical, mechanical, and environmental specifications for the RCM3700.

Table A-1. RabbitCore RCM3700 Specifications 

Parameter	RCM3700	RCM3710	RCM3720
Microprocessor	Low-EMI Rabbit 3000® at 22.1 MHz
Ethernet Port	10/100-compatible with 10Base-T interface, RJ-45, 2 LEDs
Flash Memory	512K	256K	512K
SRAM	512K	128K	256K
Serial Flash Memory	1Mbyte
Backup Battery	Connection for user-supplied backup battery (to support RTC and SRAM)
General-Purpose I/O	33 parallel digital I/0 lines: • 31 configurable I/O • 2 fixed outputs
Additional I/O	Reset
Auxiliary I/O Bus	Can be configured for 8 data lines and 5 address lines (shared with parallel I/O lines), plus I/O read/write
Serial Ports	Four 3.3 V CMOS-compatible ports configurable as: 4 asynchronous serial ports (with IrDA) or 3 clocked serial ports (SPI) plus 1 HDLC (with IrDA) or 1 clocked serial port (SPI) plus 2 HDLC serial ports (with IrDA)
Serial Rate	Maximum asynchronous baud rate = CLK/8
Slave Interface	A slave port allows the RCM3700 to be used as an intelligent peripheral device slaved to a master processor, which may either be another Rabbit 3000 or any other type of processor
Real-Time Clock	Yes
Timers	Ten 8-bit timers (6 cascadable, 3 reserved for internal peripherals), one 10-bit timer with 2 match registers
Watchdog/Supervisor	Yes
Pulse-Width Modulators	4 PWM output channels with 10-bit free-running counter and priority interrupts
Input Capture/ Quadrature Decoder	2-channel input capture can be used to time input signals from various port pins 1 quadrature decoder unit accepts inputs from external incremental encoder modules or 1 quadrature decoder unit shared with 2 PWM channels
Power	4.75–5.25 V DC 100 mA @ 22.1 MHz, 5 V; 78 mA @ 11.05 MHz, 5 V
Operating Temperature	–40°C to +70°C
Humidity	5% to 95%, noncondensing
Connectors	One 2 x 20, 0.1" pitch
Board Size	1.20" × 2.95" × 0.89" (30 mm × 75 mm × 23 mm)

A.1.1 Headers

The RCM3700 uses one header at J1 for physical connection to other boards. J1 is a 2 ×  20 SMT header with a 0.1" pin spacing.

Figure A-3 shows the layout of another board for the RCM3700 to be plugged into. These values are relative to the designated fiducial (reference point).

Figure A-3. User Board Footprint for RCM3700

A.2 Bus Loading

You must pay careful attention to bus loading when designing an interface to the RCM3700. This section provides bus loading information for external devices.

Table A-2 lists the capacitance for the various RCM3700 I/O ports.

Table A-2. Capacitance of Rabbit 3000 I/O Ports

I/O Ports	Input Capacitance (pF)	Output Capacitance (pF)
Parallel Ports A to G	12	14

Table A-3 lists the external capacitive bus loading for the various RCM3700 output ports. Be sure to add the loads for the devices you are using in your custom system and verify that they do not exceed the values in Table A-3.

Table A-3. External Capacitive Bus Loading -40°C to +85°C

Output Port	Clock Speed (MHz)	Maximum External Capacitive Loading (pF)
All I/O lines with clock doubler enabled	22.1	100

Figure A-4 shows a typical timing diagram for the Rabbit 3000 microprocessor external I/O read and write cycles.

Figure A-4. I/O Read and Write Cycles—No Extra Wait States

NOTE	/IOCSx can be programmed to be active low (default) or active high.

Table A-4 lists the delays in gross memory access time.

Table A-4. Data and Clock Delays VIN ±10%, Temp, -40°C–+85°C (maximum)

VIN	Clock to Address Output Delay (ns)			Data Setup Time Delay (ns)	Spectrum Spreader Delay (ns)
	30 pF	60 pF	90 pF		Normal no dbl/dbl	Strong no dbl/dbl
3.3 V	6	8	11	1	3/4.5	4.5/9

The measurements are taken at the 50% points under the following conditions.

• T = -40°C to 85°C, V = V_DD ±10%

• Internal clock to nonloaded CLK pin delay £ 1 ns @ 85°C/3.0 V

The clock to address output delays are similar, and apply to the following delays.

• T_adr, the clock to address delay

• T_CSx, the clock to memory chip select delay

• T_IOCSx, the clock to I/O chip select delay

• T_IORD, the clock to I/O read strobe delay

• T_IOWR, the clock to I/O write strobe delay

• T_BUFEN, the clock to I/O buffer enable delay

The data setup time delays are similar for both T_setup and T_hold.

When the spectrum spreader is enabled with the clock doubler, every other clock cycle is shortened (sometimes lengthened) by a maximum amount given in the table above. The shortening takes place by shortening the high part of the clock. If the doubler is not enabled, then every clock is shortened during the low part of the clock period. The maximum shortening for a pair of clocks combined is shown in the table.

Technical Note TN227, Interfacing External I/O with Rabbit 2000/3000 Designs, contains suggestions for interfacing I/O devices to the Rabbit 3000 microprocessors.

A.3 Rabbit 3000 DC Characteristics

Table A-5. Rabbit 3000 Absolute Maximum Ratings

Symbol	Parameter	Maximum Rating
TA	Operating Temperature	-55° to +85°C
TS	Storage Temperature	-65° to +150°C
	Maximum Input Voltage: Oscillator Buffer Input 5-V-tolerant I/O	VDD + 0.5 V 5.5 V
VDD	Maximum Operating Voltage	3.6 V

Stresses beyond those listed in Table A-5 may cause permanent damage. The ratings are stress ratings only, and functional operation of the Rabbit 3000 chip at these or any other conditions beyond those indicated in this section is not implied. Exposure to the absolute maximum rating conditions for extended periods may affect the reliability of the Rabbit 3000 chip.

Table A-6 outlines the DC characteristics for the Rabbit 3000 at 3.3 V over the recommended operating temperature range from T_A = –55°C to +85°C, V_DD = 3.0 V to 3.6 V.

Table A-6. 3.3 Volt DC Characteristics

Symbol	Parameter	Test Conditions	Min	Typ	Max	Units
VDD	Supply Voltage		3.0	3.3	3.6	V
VIH	High-Level Input Voltage		2.0			V
VIL	Low-Level Input Voltage				0.8	V
VOH	High-Level Output Voltage	IOH = 6.8 mA, VDD = VDD (min)	0.7 x VDD			V
VOL	Low-Level Output Voltage	IOL = 6.8 mA, VDD = VDD (min)			0.4	V
IIH	High-Level Input Current (absolute worst case, all buffers)	VIN = VDD, VDD = VDD (max)			10	µA
IIL	Low-Level Input Current (absolute worst case, all buffers)	VIN = VSS, VDD = VDD (max)	-10			µA
IOZ	High-Impedance State Output Current (absolute worst case, all buffers)	VIN = VDD or VSS, VDD = VDD (max), no pull-up	-10		10	µA

A.4 I/O Buffer Sourcing and Sinking Limit

Unless otherwise specified, the Rabbit I/O buffers are capable of sourcing and sinking 6.8 mA of current per pin at full AC switching speed. Full AC switching assumes a 22.1 MHz CPU clock and capacitive loading on address and data lines of less than 100 pF per pin. The absolute maximum operating voltage on all I/O is 5.5 V.

Table A-7 shows the AC and DC output drive limits of the parallel I/O buffers when the Rabbit 3000 is used in the RCM3700.

Table A-7. I/O Buffer Sourcing and Sinking Capability

Pin Name	Output Drive (Full AC Switching) Sourcing/Sinking Limits (mA)
	Sourcing	Sinking
All data, address, and I/O lines with clock doubler enabled	6.8	6.8

Under certain conditions, you can exceed the limits outlined in Table A-7. See the Rabbit 3000 Microprocessor User's Manual for additional information.

A.5 Conformal Coating

The areas around the 32 kHz real-time clock crystal oscillator have had the Dow Corning silicone-based 1-2620 conformal coating applied. The conformally coated area is shown in Figure A-5. The conformal coating protects these high-impedance circuits from the effects of moisture and contaminants over time.

Figure A-5. RCM3700 Areas Receiving Conformal Coating

Any components in the conformally coated area may be replaced using standard soldering procedures for surface-mounted components. A new conformal coating should then be applied to offer continuing protection against the effects of moisture and contaminants.

NOTE	For more information on conformal coatings, refer to Technical Note 303, Conformal Coatings.

A.6 Jumper Configurations

Figure A-6 shows the header locations used to configure the various RCM3700 options via jumpers.

Figure A-6. Location of RCM3700 Configurable Positions

Table A-8 lists the configuration options.

Table A-8. RCM3700 Jumper Configurations

Header	Description	Pins Connected		Factory Default
JP1	Flash Memory Bank Select	1–2	Normal Mode	×
		2–3	Bank Mode
JP2	SRAM Size	1–2	128K–256K	RCM3710 RCM3720
		2–3	512K	RCM3700
JP3	Flash Memory Size	1–2	256K	RCM3710
		2–3	512K	RCM3700 RCM3720

NOTE	The jumper connections are made using 0 W surface-mounted resistors.