RabbitCore RCM3900 User's Manual

Appendix A. RCM3900 Specifications

Appendix A provides the specifications for the RCM3900, and describes the conformal coating.

A.1 Electrical and Mechanical Characteristics

Figure A-1 shows the mechanical dimensions for the RCM3900.

Figure A-1. RCM3900 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 RCM3900 in all directions when the RCM3900 is incorporated into an assembly that includes other printed circuit boards. An "exclusion zone" of 0.16" (4 mm) is recommended below the RCM3900 when the RCM3900 is plugged into another assembly using the shortest connectors for header J1. Figure A-2 shows this "exclusion zone."

Figure A-2. RCM3900 "Exclusion Zone"

Table A-1 lists the electrical, mechanical, and environmental specifications for the RCM3900.

Table A-1. RabbitCore RCM3900 Specifications 

Parameter	RCM3900	RCM3910
Microprocessor	Low-EMI Rabbit® 3000 at 44.2 MHz
EMI Reduction	Spectrum spreader for reduced EMI (radiated emissions)
Ethernet Port	10/100Base-T, RJ-45, 3 LEDs
SRAM	512K program (fast SRAM) + 512K data
Flash Memory (program)	512K
Memory (data storage)	32MB (fixed NAND flash) + 128MB–1GB miniSD™ Card	128MB–1GB miniSD™ Card
LED Indicators	LINK/ACT (link/activity) FDX/COL (full-duplex/collisions) SPEED (on for 100Base-T Ethernet connection) CE/BSY (not used/user-programmable)
Backup Battery	Connection for user-supplied backup battery (to support RTC and data SRAM)
General-Purpose I/O	52 parallel digital I/0 lines: · 44 configurable I/O · 4 fixed inputs · 4 fixed outputs
Additional Inputs	Startup mode (2), reset in
Additional Outputs	Status, reset out
External 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	Five 3.3 V, CMOS-compatible ports (shared with I/O) all 5 configurable as asynchronous (with IrDA) 3 configurable as clocked serial (SPI) 2 configurable as SDLC/HDLC 1 asynchronous serial port dedicated for programming
Serial Rate	Maximum asynchronous baud rate = CLK/8
Slave Interface	A slave port allows the RCM3900/RCM3910 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 registers with 10-bit free-running counter and priority interrupts
Input Capture	2-channel input capture can be used to time input signals from various port pins
Quadrature Decoder	2-channel quadrature decoder accepts inputs from external incremental encoder modules
Power	3.15–3.45 V DC 325 mA @ 44.2 MHz, 3.3 V
Operating Temperature	-20°C to +85°C
Humidity	5% to 95%, noncondensing
Connectors	Two 2 × 17, 2 mm pitch One 2 × 5 for programming with 1.27 mm pitch One miniSD™ Card socket
Board Size	1.850" × 2.725" × 0.86" (47 mm × 69 mm × 22 mm)

A.1.1 Headers

The RCM3900 uses headers at J61 and J62 for physical connection to other boards. J61 and J62 are 2 ×  17 SMT headers with a 2 mm pin spacing. J1, the programming port, is a 2 ×  5 header with a 1.27 mm pin spacing.

Figure A-3 shows the layout of another board for the RCM3900 to be plugged into. These values are relative to the mounting hole.

Figure A-3. User Board Footprint for RCM3900

A.2 Bus Loading

You must pay careful attention to bus loading when designing an interface to the RCM3900. This section provides bus loading information for external devices.

Table A-2 lists the capacitance for the various RCM3900 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 RCM3900 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 RCM3900.

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. RCM3900 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 Rabbit's Technical Note 303, Conformal Coatings in the online document suite.

A.6 Jumper Configurations

Figure A-6 shows the header locations used to configure the various RCM3900 options via jumpers.

Figure A-6. Location of RCM3900 Configurable Positions

Table A-8 lists the configuration options.

Table A-8. RCM3900 Jumper Configurations

Header	Description	Pins Connected		Factory Default
JP1	Serial Flash Chip Enable Indicator	1–2		n.c.
JP2	ACT or PD1 Output on J61 pin 34	1–2	ACT	×
		2–3	PD1
JP3	LINK or PD0 Output on J61 pin 33	1–2	LINK	×
		2–3	PD0
JP4	ENET or PE0 Output on J62 pin 19	1–2	ENET
		2–3	PE0	×
JP5	NAND Flash Chip Enable	1–2	Reserved for future use
		2–3	PD1 controls NAND Flash	RCM3900 only
JP7	PD6 or TPI– Input on J61 pin 31	1–2	TPI–
		2–3	PD6	×
JP8	PD7 or TPI+ Input on J61 pin 32	1–2	TPI+
		2–3	PD7	×
JP9	PD2 or TPO– Output on J61 pin 29	1–2	TPO–	n.c.
		2–3	PD2
JP10	PD3 or TPO+ Output on J61 pin 30	1–2	TPO+
		2–3	PD3	×
JP11	Flash Memory Size	1–2	256K
		2–3	512K	×
JP12	Flash Memory Bank Select	1–2	Normal Mode	×
		2–3	Bank Mode
JP13	Data SRAM Size	1–2	256K
		2–3	512K	×
JP14	LED DS1 Display	1–2	FDX/COL displayed by LED DS1	×
		2–3	Optional ACT displayed by LED DS1

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