Rabbit 2000 User manual

Rabbit 2000®Microprocessor
User’s Manual
019–0069 • 041018–M
®

Rabbit 2000 Microprocessor
Rabbit Semiconductor
2932 Spafford Street
Davis, California 95616-6800
USA
Telephone: [phone]
Fax: [phone]
www.rabbitsemiconductor.com
Rabbit 2000 Microprocessor User’s Manual
Part Number 019-0069 • 041018–M • Printed in U.S.A.
©1999–2004 Rabbit Semiconductor • All rights reserved.
Rabbit Semiconductor reserves the right to make changes and
improvements to its products without providing notice.
Trademarks
Rabbit and Rabbit 2000 are registered trademarks of Rabbit Semiconductor.
Dynamic C is a registered trademark of Z-World, Inc.

User’s Manual
TABLE OF CONTENTS
Chapter 1. Introduction 1
1.1 Features and Specifications ..................................................................................................................1
1.2 Summary of Rabbit Advantages...........................................................................................................5
Chapter 2. Rabbit Design Features 7
2.1 The Rabbit 8-bit Processor vs. 16-bit and 32-bit Processors................................................................8
2.2 Overview of On-Chip Peripherals ........................................................................................................8
2.2.1 Serial Ports ...................................................................................................................................8
2.2.2 System Clock ...............................................................................................................................8
2.2.3 Time/Date Oscillator ....................................................................................................................9
2.2.4 Parallel I/O ...................................................................................................................................9
2.2.5 Slave Port ...................................................................................................................................10
2.2.6 Timers ........................................................................................................................................10
2.3 Design Standards ................................................................................................................................12
2.3.1 Programming Port ......................................................................................................................12
2.3.2 Standard BIOS ...........................................................................................................................12
2.4 Dynamic C Support for the Rabbit ....................................................................................................12
Chapter 3. Details on Rabbit
Microprocessor Features 13
3.1 Processor Registers.............................................................................................................................13
3.2 Memory Mapping ...............................................................................................................................15
3.2.1 Extended Code Space .................................................................................................................18
3.2.2 Extending Data Memory ............................................................................................................19
3.2.3 Practical Memory Considerations ..............................................................................................21
3.3 Instruction Set Outline........................................................................................................................22
3.3.1 Load Immediate Data To a Register ..........................................................................................23
3.3.2 Load or Store Data from or to a Constant Address ....................................................................23
3.3.3 Load or Store Data Using an Index Register .............................................................................24
3.3.4 Register to Register Move ..........................................................................................................25
3.3.5 Register Exchanges ....................................................................................................................25
3.3.6 Push and Pop Instructions ..........................................................................................................26
3.3.7 16-bit Arithmetic and Logical Ops ............................................................................................26
3.3.8 Input/Output Instructions ...........................................................................................................29
3.4 How to Do It in Assembly Language—Tips and Tricks....................................................................31
3.4.1 Zero HL in 4 Clocks ...................................................................................................................31
3.4.2 Exchanges Not Directly Implemented .......................................................................................31
3.4.3 Manipulation of Boolean Variables ...........................................................................................31
3.4.4 Comparisons of Integers ............................................................................................................32
3.4.5 Atomic Moves from Memory to I/O Space ...............................................................................34
3.5 Interrupt Structure...............................................................................................................................35
3.5.1 Interrupt Priority ........................................................................................................................35
3.5.2 Multiple External Interrupting Devices .....................................................................................37
3.5.3 Privileged Instructions, Critical Sections and Semaphores .......................................................37
3.5.4 Critical Sections .........................................................................................................................38
3.5.5 Semaphores Using Bit B,(HL) ...................................................................................................38
3.5.6 Computed Long Calls and Jumps ..............................................................................................39

Rabbit 2000 Microprocessor
Chapter 4. Rabbit Capabilities 41
4.1 Precisely Timed Output Pulses ..........................................................................................................41
4.1.1 Pulse Width Modulation to Reduce Relay Power .....................................................................43
4.2 Open-Drain Outputs Used for Key Scan............................................................................................44
4.3 Cold Boot ...........................................................................................................................................45
4.4 The Slave Port....................................................................................................................................46
4.4.1 Slave Rabbit As A Protocol UART ...........................................................................................47
Chapter 5. Pin Assignments and Functions 49
5.1 Package Schematic and Pinout...........................................................................................................49
5.2 Package Mechanical Dimensions.......................................................................................................50
5.3 Rabbit Pin Descriptions......................................................................................................................52
5.4 Bus Timing.........................................................................................................................................58
5.5 Description of Pins with Alternate Functions ....................................................................................59
5.6 DC Characteristics..............................................................................................................................61
5.6.1 5.0 Volts ....................................................................................................................................62
5.6.2 3.3 Volts ....................................................................................................................................63
5.7 I/O Buffer Sourcing and Sinking Limit..............................................................................................64
Chapter 6. Rabbit Internal I/O Registers 65
6.1 Default Values for all the Peripheral Control Registers.....................................................................65
Chapter 7. Miscellaneous I/O Functions 71
7.1 Processor Identification......................................................................................................................71
7.2 Rabbit Oscillators and Clocks............................................................................................................72
7.3 Clock Doubler....................................................................................................................................74
7.4 Controlling Power Consumption........................................................................................................76
7.5 Output Pins CLK, STATUS, /WDTOUT, /BUFEN..........................................................................77
7.6 Time/Date Clock (Real-Time Clock).................................................................................................78
7.7 Watchdog Timer.................................................................................................................................80
7.8 System Reset ......................................................................................................................................82
7.9 Rabbit Interrupt Structure...................................................................................................................84
7.9.1 External Interrupts .....................................................................................................................86
7.9.2 Interrupt Vectors: INT0 - EIR,0x00/INT1 - EIR,0x08 ..............................................................87
7.10 Bootstrap Operation .........................................................................................................................88
Chapter 8. Memory Mapping and Interface 91
8.1 Memory-Mapping Unit......................................................................................................................91
8.2 Memory Interface Unit.......................................................................................................................93
8.3 Memory Control Unit Registers.........................................................................................................94
8.3.1 Memory Bank Control Registers ...............................................................................................94
8.3.2 MMU Instruction/Data Register ................................................................................................95
8.3.3 Memory Timing Control Register .............................................................................................95
8.4 Allocation of Extended Code and Data..............................................................................................96
8.5 How Compiler Compiles to Memory.................................................................................................97
Chapter 9. Parallel Ports 99
9.1 Parallel Port A..................................................................................................................................100
9.2 Parallel Port B ..................................................................................................................................101
9.3 Parallel Port C ..................................................................................................................................102
9.4 Parallel Port D..................................................................................................................................103
9.5 Parallel Port E...................................................................................................................................106
Chapter 10. I/O Bank Control Registers 109

User’s Manual
Chapter 11. Timers 111
11.1 Timer A...........................................................................................................................................112
11.1.1 Timer A I/O Registers ............................................................................................................113
11.1.2 Practical Use of Timer A .......................................................................................................114
11.2 Timer B...........................................................................................................................................115
11.2.1 Using Timer B ........................................................................................................................117
Chapter 12. Rabbit Serial Ports 119
12.1 Serial Port Register Layout.............................................................................................................120
12.2 Serial Port Interrupt ........................................................................................................................123
12.3 Transmit Serial Data Timing ..........................................................................................................124
12.4 Receive Serial Data Timing............................................................................................................124
12.5 Clocked Serial Ports........................................................................................................................125
12.6 Clocked Serial Timing....................................................................................................................128
12.6.1 Clocked Serial Timing With Internal Clock ..........................................................................128
12.6.2 Clocked Serial Timing with External Clock ..........................................................................128
12.7 Serial Port Software Suggestions....................................................................................................129
12.7.1 Controlling an RS-485 Driver and Receiver ..........................................................................131
12.7.2 Transmitting Dummy Characters ...........................................................................................131
12.7.3 Transmitting and Detecting a Break ......................................................................................131
12.7.4 Using A Serial Port to Generate a Periodic Interrupt .............................................................131
12.7.5 Extra Stop Bits, Sending Parity, 9th Bit Communication Schemes .......................................132
12.7.6 Supporting 9th Bit Communication Protocols .......................................................................134
12.7.7 Rabbit-Only Master/Slave Protocol .......................................................................................135
12.7.8 Data Framing/Modbus ...........................................................................................................135
Chapter 13. Rabbit Slave Port 137
13.1 Hardware Design of Slave Port Interconnection ............................................................................143
13.2 Slave Port Registers........................................................................................................................143
13.3 Applications and Communications Protocols for Slaves................................................................145
13.3.1 Slave Applications .................................................................................................................145
13.3.2 Master-Slave Messaging Protocol .........................................................................................146
Chapter 14. Rabbit 2000 Clocks 149
14.1 Low-Power Design .........................................................................................................................150
14.2 Clock Spectrum Spreader Module..................................................................................................150
Chapter 15. AC Timing Specifications 151
15.1 Memory Access and I/O Read/Write Times...................................................................................154
15.2 Current Consumption......................................................................................................................162
Chapter 16. Rabbit BIOS and Virtual Driver 165
16.1 The BIOS........................................................................................................................................165
16.1.1 BIOS Services ........................................................................................................................165
16.1.2 BIOS Assumptions .................................................................................................................166
16.2 Virtual Driver..................................................................................................................................166
16.2.1 Periodic Interrupt ...................................................................................................................166
16.2.2 Watchdog Timer Support .......................................................................................................166
Chapter 17. Other Rabbit Software 169
17.1 Power Management Support...........................................................................................................169
17.2 Reading and Writing I/O Registers.................................................................................................170
17.2.1 Using Assembly Language ....................................................................................................170
17.2.2 Using Library Functions ........................................................................................................170
17.3 Shadow Registers............................................................................................................................171
17.3.1 Updating Shadow Registers ...................................................................................................171
17.3.2 Interrupt While Updating Registers .......................................................................................171
17.3.3 Write-only Registers Without Shadow Registers ..................................................................172
17.4 Timer and Clock Usage ..................................................................................................................172

Rabbit 2000 Microprocessor
Chapter 18. Rabbit Instructions 175
18.1 Load Immediate Data.....................................................................................................................178
18.2 Load & Store to Immediate Address..............................................................................................178
18.3 8-bit Indexed Load and Store.........................................................................................................178
18.4 16-bit Indexed Loads and Stores....................................................................................................178
18.5 16-bit Load and Store 20-bit Address ............................................................................................179
18.6 Register to Register Moves............................................................................................................179
18.7 Exchange Instructions ....................................................................................................................180
18.8 Stack Manipulation Instructions.....................................................................................................180
18.9 16-bit Arithmetic and Logical Ops.................................................................................................180
18.10 8-bit Arithmetic and Logical Ops.................................................................................................181
18.11 8-bit Bit Set, Reset and Test.........................................................................................................182
18.12 8-bit Increment and Decrement....................................................................................................182
18.13 8-bit Fast A register Operations...................................................................................................183
18.14 8-bit Shifts and Rotates ................................................................................................................183
18.15 Instruction Prefixes ......................................................................................................................184
18.16 Block Move Instructions..............................................................................................................184
18.17 Control Instructions - Jumps and Calls........................................................................................185
18.18 Miscellaneous Instructions...........................................................................................................185
18.19 Privileged Instructions..................................................................................................................186
Chapter 19. Differences Rabbit vs. Z80/Z180 Instructions 187
Chapter 20. Instructions in Alphabetical Order With Binary Encoding 189
Appendix A. 197
A.1 The Rabbit Programming Port ........................................................................................................197
A.2 Use of the Programming Port as a Diagnostic/Setup Port...............................................................198
A.3 Alternate Programming Port ...........................................................................................................198
A.4 Suggested Rabbit Crystal Frequencies............................................................................................199
Appendix B. 201
B.1 Rabbit 2000 Revisions.....................................................................................................................201
B.2 Discussion of Fixes and Improvements...........................................................................................203
B.2.1 Rabbit Internal I/O Registers ..................................................................................................204
B.2.2 Revision-Level ID Register ....................................................................................................205
B.2.3 Serial Port Changes .................................................................................................................207
B.2.4 Improved Battery-Backup Circuit .......................................................................................... 209
B.2.5 Added Support for Instruction/Data Split ...............................................................................211
B.2.6 Write Inhibit (/WE0) After Reset ...........................................................................................213
B.2.7 Chip Selects Inactive During Internal I/O ..............................................................................213
B.2.8 External Interrupt Input Bug Fix ............................................................................................213
B.2.9 IOI/IOE Prefix Bug Fix ..........................................................................................................213
B.2.10 DDCB/FDCB Instruction Page and Wait State Bug Fixes ...................................................214
B.2.11 LDIR/LDDR Instruction/Data Split Bug Fix ........................................................................214
B.2.12 Clock Spectrum Spreader Module ........................................................................................215
B.2.13 Early Memory Output-Enable Feature .................................................................................218
Notice to Users 219
Index 221

User’s Manual 1
1. INTRODUCTION
Rabbit Semiconductor was formed expressly to design a a better microprocessor for use in
small and medium-scale controllers. The first product is the Rabbit 2000 microprocessor.
The Rabbit 2000 designers have had years of experience using Z80, Z180 and HD64180
microprocessors in small controllers. The Rabbit shares a similar architecture and a high
degree of compatibility with these microprocessors, but it is a vast improvement.
The Rabbit has been designed in close cooperation with Z-World, Inc., a long-time manu-
facturer of low-cost single-board computers. Z-World’s products are supported by an
innovative C-language development system (Dynamic C). Z-World is providing the soft-
ware development tools for the Rabbit.
The Rabbit 2000 is easy to use. Hardware and software interfaces are as uncluttered and
are as foolproof as possible. The Rabbit 2000 has outstanding computation speed for a
microprocessor with an 8-bit bus. This is because the Z80-derived instruction set is very
compact and the design of the memory interface allows maximum utilization of the mem-
ory bandwidth. The Rabbit races through instructions.
Traditional microprocessor hardware and software development is simplified for Rabbit
users. In-circuit emulators are not needed and will not be missed by the Rabbit developer.
Software development is accomplished by connecting a simple interface cable from a PC
serial port to the Rabbit-based target system.
1.1 Features and Specifications
•100-pin PQFP package. Operating voltage 2.7 V to 5 V. Clock speed to 30 MHz. All
specifications are given for both industrial and commercial temperature and voltage
ranges. Rabbit microprocessors cost under $10 in moderate quantities.
•Industrial specifications are for a voltage variation of 10% and a temperature range
from –40°C to +85°C. Commercial specifications are for a voltage variation of 5% and
a temperature range from 0°C to 70°C.
•1-megabyte code space allows C programs with up to 50,000+ lines of code. The
extended Z80-style instruction set is C-friendly, with short and fast instructions for
most common C operations.
•Four levels of interrupt priority make a fast interrupt response practical for critical
applications. The maximum time to the first instruction of an interrupt routine is about
1 µs at a clock speed of 25 MHz.

2Rabbit 2000 Microprocessor
•Access to I/O devices is accomplished by using memory access instructions with an I/O
prefix. Access to I/O devices is thus faster and easier compared to processors with a
restricted I/O instruction set.
•The hardware design rules are simple. Up to six static memory chips (such as RAM and
flash EPROM) connect directly to the microprocessor with no glue logic. Even larger
amounts of memory can be handled by using parallel I/O lines as high-order address
lines. The Rabbit runs with no wait states at 24 MHz with a memory having an access
time of 70 ns. There are two clocks per memory access. Most I/O devices may be con-
nected without glue logic.
The memory cycle is two clocks long. A clean memory and I/O cycle completely avoid
the possibility of tri-state fights. Peripheral I/O devices can usually be interfaced in a
glueless fashion using pins programmable as I/O chip selects, I/O read strobes or I/O
write strobe pins. A built-in clock doubler allows ½-frequency crystals to be used to
reduce radiated emissions.
•The Rabbit may be cold-booted via a serial port or the parallel access slave port. This
means that flash program memory may be soldered in unprogrammed, and can be
reprogrammed at any time without any assumption of an existing program or BIOS. A
Rabbit that is slaved to a master processor can operate entirely with volatile RAM,
depending on the master for a cold program boot.
•There are 40 parallel I/O lines (shared with serial ports). Some I/O lines are timer syn-
chronized, which permits precisely timed edges and pulses to be generated under com-
bined hardware and software control.
•There are four serial ports. All four serial ports can operate asynchronously in a variety
of customary operating modes; two of the ports can also be operated synchronously to
interface with serial I/O devices. The baud rates can be very high—1/32 the clock
speed for asynchronous operation, and 1/6 the clock speed externally or 1/4 the clock
speed internally in synchronous mode. In asynchronous mode, the Rabbit, like the
Z180, supports sending flagged bytes to mark the start of a message frame. The flagged
bytes have 9 data bits rather than 8 data bits; the extra bit is located after the first 8 bits,
where the stop bit is normally located, and marks the start of a message frame.
•A slave port allows the Rabbit to be used as an intelligent peripheral device slaved to a
master processor. The 8-bit slave port has six 8-bit registers, 3 for each direction of
communication. Independent strobes and interrupts are used to control the slave port in
both directions. Only a Rabbit and a RAM chip are needed to construct a complete
slave system if the clock and reset are shared with the master processor
•The built-in battery-backable time/date clock uses an external 32.768 kHz crystal. The
time/date clock can also be used to provide periodic interrupts every 488 µs. Typical
battery current consumption is 25 µA with the suggested battery circuit. An alternative
circuit provides means for substantially reducing this current.
•Numerous timers and counters (six all together) can be used to generate interrupts,
baud rate clocks, and timing for pulse generation.

User’s Manual 3
•The built-in main clock oscillator uses an external crystal or more usually a ceramic
resonator. Typical resonator frequencies are in the range of 1.8 MHz to 29.5 MHz.
Since precision timing is available from the separate 32.768 kHz oscillator, a low-cost
ceramic resonator with ½ percent error is generally satisfactory. The clock can be dou-
bled or divided by 8 to modify speed and power dynamically. The I/O clock, which
clocks the serial ports, is divided separately so as not to affect baud rates and timers
when the processor clock is divided or multiplied. For ultra low power operation, the
processor clock can be driven from the separate 32.768 kHz oscillator and the main
oscillator can be powered down. This allows the processor to operate at approximately
100 µA and still execute instructions at the rate of approximately 10,000 instructions
per second. This is a powerful alternative to sleep modes of operation used by other
processors. The current is approximately 65 mA at 25 MHz and 5 V. The current is pro-
portional to voltage and clock speed—at 3.3 V and 7.68 MHz the current would be 13
mA, and at 1 MHz the current is reduced to less than 2 mA. Flash memory with auto-
matic power down (from AMD) should be used for operation at the lowest power.
•The excellent floating-point performance is due to a tightly coded library and powerful
processing capability. For example, a 25 MHz clock takes 14 µs for a floating add,
13 µs for a multiply, and 40 µs for a square root. In comparison, a 386EX processor
running with an 8-bit bus at 25 MHz and using Borland C is about 10 times slower.
•There is a built-in watchdog timer.
•The standard 10-pin programming port eliminates the need for in-circuit emulators. A
very simple 10 pin connector can be used to download and debug software using
Z-World’s Dynamic C and a simple connection to a PC serial port. The incremental cost
of the programming port is extremely small.

4Rabbit 2000 Microprocessor
Figure 1-1 shows a block diagram of the Rabbit.
Figure 1-1. Block Diagram of the Rabbit Microprocessor
CPU
External Interface
Data
Buffer
Memory
Management/
Control
Address
Buffer
Memory Chip
Interface
Parallel
Port A
Parallel
Port B
Parallel
Port C
Parallel
Port D
Glo al
Control
Main
Oscillator
Parallel
Port E
Timer A
Timer B
Serial Port A
Asynch
Serial
Synch
Serial
Asynch
Bootstrap
Synch
Bootstrap
Real-Time
Clock
Serial Port B
Asynchronous
Serial
Synchronous
Serial
32.768 kHz
Oscillator
Watchdog
Timer
Asynchronous
Serial
Serial Port C
Periodic
Interrupts
Asynchronous
Serial
Serial Port D
External I/O
Chip Interface
Slave Port
Slave Interface
External
Interrupts
/RESET
/IOWR
/IORD /BUFEN
SMODE0
SMODE1
STATUS
/WDTOUT
CLK
DATA BUS
(8 its)
D0D7
A0A19
XTALB1
XTALB2
XTALA1
XTALA2
I0I7
INT0A, INT1A
INT0B, INT1B
/CS0, /CS1, /CS2
/OE0, /OE1
/WE0, /WE1
PA0PA7
PB0PB7
PC0PC7
PD0PD7
PE0PE7
TXA, RXA, CLKA,
ATXA, ARXA
TXB, RXB, CLKB,
ATXB, ARXB
TXC, RXC
TXD, RXD
SD0SD7,
SA0SA1,
/SCS, /SRD, /SWR,
/SLAVEATTN
ADDRESS BUS
(8 its)
Bootstrap Interface