2. Hardware Reference

Chapter 2 describes the hardware components and principal hardware subsystems of the RCM3000. Appendix A, "RabbitCore RCM3000 Specifications," provides complete physical and electrical specifications.

Figure 1 shows these Rabbit-based subsystems designed into the RCM3000.

Figure 1. RCM3000 Subsystems

2.1 RCM3000 Digital Inputs and Outputs

The RCM3000 has 40 parallel I/O lines grouped in seven 8-bit ports available on headers J1 and J2. The 37 bidirectional I/O lines are located on pins PA0-PA7, PD2-PD7, PE0-PE1, PE3-PE7, PF0-PF7, and PG0-PG7.

Figure 2 shows the RCM3000 RabbitCore series pinouts for headers J1 and J2.

Figure 2. RCM3000 Pinouts

Headers J1 and J2 are standard 2 × 34 headers with a nominal 2 mm pitch. An RJ-45 Ethernet jack is also included with the RCM3000 series.

The signals labeled PD2, PD3, PD6, and PD7 on header J1 (pins 29-32) and the pins that are not connected (pins 33-34 on header J1 and pin 33 on header J2) are reserved for future use on other models in the RCM3000 series.

Figure 3 shows the use of the Rabbit 3000 ports in the RCM3000 series RabbitCore modules.

Figure 3. Use of Rabbit 3000 Ports

The ports on the Rabbit 3000 microprocessor used in the RCM3000 Series are configurable, and so the factory defaults can be reconfigured. Table 1 lists the Rabbit 3000 factory defaults and the alternate configurations.

Table 1. RCM3000 Pinout Configurations 

Pin		Pin Name	Default Use	Alternate Use	Notes
Header J1	1	GND
	2	STATUS	Output (Status)	Output
	3-10	PA[7:0]	Parallel I/O	External data bus (ID0-ID7) Slave port data bus (SD0-SD7)
	11	PF3	Input/Output	QD2A
	12	PF2	Input/Output	QD2B
	13	PF1	Input/Output	QD1A CLKC
	14	PF0	Input/Output	QD1B CLKD
	15	PC0	Output	TXD	Serial Port D
	16	PC1	Input	RXD
	17	PC2	Output	TXC	Serial Port C
	18	PC3	Input	RXC
	19	PC4	Output	TXB	Serial Port B
	20	PC5	Input	RXB
	21	PC6	Output	TXA	Serial Port A (programming port)
	22	PC7	Input	RXA
	23	PG0	Input/Output	TCLKF	Serial Clock F output
	24	PG1	Input/Output	RCLKF	Serial Clock F input
	25	PG2	Output	TXF	Serial Port F
	26	PG3	Input	RXF
	27	PD4	Input/Output	ATXB
	28	PD5	Input/Output	ARXB
	29	PD2	Input/Output	TPOUT- *	Ethernet transmit port
	30	PD3	Input/Output	TPOUT+ *
	31	PD6	Input/Output	TPIN- *	Ethernet receive port
	32	PD7	Input/Output	TPIN+ *
	33-34 *	n.c.			Not connected
* Pins 29-34 are reserved for future RCM3000 series RabbitCore modules.
Header J2	1	/RES	Reset output	Reset input	Reset output from Reset Generator
	2	PB0	Input/Output	CLKB
	3	PB2	Input/Output	IA0 /SWR	External Address 0 Slave port write
	4	PB3	Input/Output	IA1 /SRD	External Address 1 Slave port read
	5	PB4	Input/Output	IA2 SA0	External Address 2 Slave port Address 0
	6	PB5	Input/Output	IA3 SA1	External Address 3 Slave port Address 1
	7	PB6	Input/Output	IA4	External Address 4
	8	PB7	Input/Output	IA5 /SLAVEATTN	External Address 5 Slave Attention
	9	PF4	Input/Output	AQD1B PWM0
	10	PF5	Input/Output	AQD1A PWM1
	11	PF6	Input/Output	AQD2B PWM2
	12	PF7	Input/Output	AQD2A PWM3
	13	PE7	Input/Output	I7 /SCS
	14	PE6	Input/Output	I6
	15	PE5	Input/Output	I5 INT1B
	16	PE4	Input/Output	I4 INT0B
	17	PE3	Input/Output	I3
	18	PE1	Input/Output	I1 INT1A	I/O Strobe 1 Interrupt 1A
	19	PE0	Input/Output	I0 INT0A	I/O Strobe 0 Interrupt 0A
Header J2	20	PG7	Input/Output	RXE	Serial Port E
	21	PG6	Input/Output	TXE
	22	PG5	Input/Output	RCLKE	Serial Clock E input
	23	PG4	Input/Output	TCLKE	Serial Clock E ouput
	24	/IOWR	Output		External write strobe
	25	/IORD	Input		External read strobe
	26-27	SMODE0, SMODE1	(0,0)--start executing at address zero (0,1)--cold boot from slave port (1,0)--cold boot from clocked Serial Port A SMODE0 =1, SMODE1 = 1 Cold boot from asynchronous Serial Port A at 2400 bps (programming cable connected)		Also connected to programming cable
	28	/RESET_IN	Input		Input to Reset Generator
	29	VRAM	Output		Maximum Current Draw 50 µA
	30	VBAT_EXT	3 V battery Input		Minimum battery voltage 2.8 V
	31	+3.3V	Input		3.15-3.45 V DC
	32	GND
	33	n.c.			Future option for +5 V input or +5 V output
	34	GND

Locations R38-R43 allow the population of 0 W resistors (jumpers) that will be used to enable future options. These locations are currently unused.

2.1.1 Memory I/O Interface

The Rabbit 3000 address lines (A0-A19) and all the data lines (D0-D7) are routed internally to the onboard flash memory and SRAM chips. I/0 write (/IOWR) and I/0 read (/IORD) are available for interfacing to external devices.

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 PB3-PB7 can also be used as an external address bus.

When using the auxiliary I/O bus, you must add the following line at the beginning of your program.

#define PORTA_AUX_IO    // required to enable auxiliary I/O bus

The STATUS output has three different programmable functions:

1. It can be driven low on the first op code fetch cycle.

2. It can be driven low during an interrupt acknowledge cycle.

3. It can also serve as a general-purpose output.

2.1.2 Other Inputs and Outputs

Two status mode pins, SMODE0 and SMODE1, are available as inputs. The logic state of these two pins determines the startup procedure after a reset.

/RESET_IN is an external input used to reset the Rabbit 3000 microprocessor and the RabbitCore RCM3000 memory. /RES is an output from the reset circuitry that can be used to reset other peripheral devices.

2.2 Serial Communication

The RCM3000 Series board does not have an RS-232 or an RS-485 transceiver directly on the board. However, an RS-232 or RS-485 interface may be incorporated on the board the RCM3000 is mounted on. For example, the Prototyping Board has a standard RS-232 transceiver chip.

2.2.1 Serial Ports

There are six serial ports designated as Serial Ports A, B, C, D, E, and F. All six serial ports can operate in an asynchronous mode up to the baud rate of the system clock divided by 16. An asynchronous port can handle 7 or 8 data bits. A 9th bit address scheme, where an additional bit is sent to mark the first byte of a message, is also supported. Serial Ports A, B, C, and D can also be operated in the clocked serial mode. In this mode, a clock line synchronously clocks the data in or out. Either of the two communicating devices can supply the clock. When the Rabbit 3000 provides the clock, the baud rate can be up to 80% of the system clock frequency divided by 128, or 183,750 bps for a 29.4 MHz clock speed.

Serial Ports E and F can also be configured as SDLC/HDLC serial ports. The IRDA protocol is also supported in SDLC format by these two ports.

Serial Port A is available only on the programming port, and so is likely to be inconvenient to interface with.

2.2.2 Ethernet Port

Figure 4 shows the pinout for the RJ-45 Ethernet port (J4). Note that some Ethernet connectors are numbered in reverse to the order used here.

Figure 4. RJ-45 Ethernet Port Pinout

Two LEDs are placed next to the RJ-45 Ethernet jack, one to indicate an Ethernet link (LNK) and one to indicate Ethernet activity (ACT).

The Ethernet signals are also available on header J1.

The transformer/connector assembly ground is connected to the RCM3000 printed circuit board digital ground via a 0 W resistor, R31, as shown in Figure 5.

Figure 5. Isolation Resistor R31

The RJ-45 connector is shielded to minimize EMI effects to/from the Ethernet signals.

2.2.3 Programming Port

Serial Port A has special features that allow it to cold-boot the system after reset. Serial Port A is also the port that is used for software development under Dynamic C.

The RabbitCore RCM3000 Series has a 10-pin program header labeled J3. The Rabbit 3000 startup-mode pins (SMODE0, SMODE1) are presented to the programming port so that an externally connected device can force the RCM3000 to start up in an external bootstrap mode. The Rabbit 3000 Microprocessor User's Manual provides more information related to the bootstrap mode.

The programming port is used to start the RabbitCore RCM3000 in a mode where it will download a program from the port and then execute the program. The programming port transmits information to and from a PC while a program is being debugged in-circuit.

The RabbitCore RCM3000 can be reset from the programming port via the /RESET_IN line.

The Rabbit 3000 status pin is also presented to the programming port. The status pin is an output that can be used to send a general digital signal.

The clock line for Serial Port A is presented to the programming port, which makes synchronous serial communication possible.

2.2.3.1 Alternate Uses of the Programming Port

The programming port may also be used as an application port with the DIAG connector on the programming cable.

All three clocked Serial Port A signals are available as

• a synchronous serial port

• an asynchronous serial port, with the clock line usable as a general CMOS input

• two general CMOS inputs and one general CMOS output.

Two startup mode pins, SMODE0 and SMODE1, are available as general CMOS inputs after they are read during the initial boot-up. The logic state of these two pins is very important in determining the startup procedure after a reset.

/RES_IN is an external input used to reset the Rabbit 3000 microprocessor.

The status pin may also be used as a general CMOS output.

See Appendix E, "Programming Cable," for more information.

2.3 Other Hardware

2.3.1 Clock Doubler

The RCM3000 takes advantage of the Rabbit 3000 microprocessor's internal clock doubler. A built-in clock doubler allows half-frequency crystals to be used to reduce radiated emissions. The 29.4 MHz frequency specified for the RCM3000 is generated using a 14.7456 MHz crystal. The clock doubler will not work for crystals with a frequency above 52.8384 MHz.

The clock doubler may be disabled if 29.4 MHz clock speeds are not required. Disabling the Rabbit 3000 microprocessor's internal clock doubler will reduce power consumption and further reduce radiated emissions. The clock doubler is disabled with a simple change to the BIOS as described below.

Open the BIOS source code file, RABBITBIOS.C in the BIOS directory. Change the line #define CLOCK_DOUBLED 1 // set to 1 to double clock if // Rabbit 2000: crystal <= 12.9024 MHz, // Rabbit 3000: crystal <= 52.8384 MHz, // or to 0 to always disable clock doubler to read as follows. #define CLOCK_DOUBLED 0 Save the change using File > Save.

2.3.2 Spectrum Spreader

The Rabbit 3000 features a spectrum spreader, which helps to mitigate EMI problems. By default, the spectrum spreader is on automatically, but it may also be turned off or set to a stronger setting. The means for doing so is through a simple change to the following BIOS line in a way that is similar to the clock doubler described above.

#define ENABLE_SPREADER 1  // Set to 0 to disable spectrum spreader.

#define SPREADER_SETTING 0 // 0 = normal spreading, 1 = strong spreading

NOTE	The strong spectrum-spreading setting is not recommended since it may limit the maximum clock speed or the maximum baud rate.

2.4 Memory

2.4.1 SRAM

The RCM3000 is designed to accept 128K to 512K of SRAM packaged in a 32-pin TSOP or sTSOP case.

2.4.2 Flash EPROM

The RCM3000 is also designed to accept 256K to 512K of flash EPROM packaged in a 32-pin TSOP or sTSOP case.

NOTE	Z-World recommends that any customer applications should not be constrained by the sector size of the flash EPROM since it may be necessary to change the sector size in the future.

Writing to arbitrary flash memory addresses at run time is also discouraged. Instead, define a "user block" area to store persistent data. The functions writeUserBlock and readUserBlock are provided for this.

A Flash Memory Bank Select jumper configuration option based on 0 W surface-mounted resistors exists at header JP1 on the RCM3000 Series RabbitCore modules. This option, used in conjunction with some configuration macros, allows Dynamic C to compile two different co-resident programs for the upper and lower halves of the 256K flash in such a way that both programs start at logical address 0000. This is useful for applications that require a resident download manager and a separate downloaded program. See Application Note 218, Implementing a Serial Download Manager for a 256K Flash, for details.

2.4.3 Dynamic C BIOS Source Files

The Dynamic C BIOS source files handle different standard RAM and flash EPROM sizes automatically.