Rabbit Semiconductor

Last updated
Rabbit Semiconductor Inc.
Industry microcontrollers
Founded1983
Headquarters,
Owner Digi International
Website www.digi.com/lp/rabbit

Rabbit Semiconductor is an American company which designs and sells the Rabbit family of microcontrollers and microcontroller modules. For development, it provides Dynamic C, a non-standard dialect of C with proprietary structures for multitasking.

Contents

Rabbit Semiconductor was purchased in 2006 by Digi International for $49 million. [1] [2] Before the purchase, Rabbit Semiconductor was a division of Z-World, Inc. Z-World developed and manufactured embedded controller products as well as embedded software development environments.

Microcontroller architecture

The Rabbit processor family shares many features with the Zilog Z80/Z180 processors. For example, the registers of a Rabbit 2000/3000 processor are almost the same as the registers of a Z80/Z180 processor. The Rabbit 4000 processor expands to include the use of 32-bit registers. The instruction set of Rabbit processors also closely resembles the instruction set of the Z80/Z180 family. While the opcodes of many instructions are the same between the Rabbit 2000/3000 processors and Z80/Z180 processors, the two families of processors are not binary compatible. As with the Z80/Z180 family, the Rabbit processors are CISC processors.

The Rabbit processor family has unique features. For example, the Z80/Z180 family disables interrupts once an interrupt is serviced by an interrupt service routine. However, the Rabbit processors permit interrupts to interrupt service routines according to priorities (a total of 4).

Rabbit Semiconductor claims that the instruction set of Rabbit processors is optimized for C code. [3]

Dynamic C

Perhaps the most notable feature of the Rabbit microcontroller is its development environment. Dynamic C, a product of Rabbit Semiconductor, has additions, deletions and inconsistencies compared to the ANSI-C standard.

The Dynamic C IDE comes with extensive open-source libraries and sample code released under the MPL license or ISC license. [4] [5]

Note
(Reference: Porting a Program to Dynamic C-Rabbit Semiconductor)

Dynamic C follows the ISO/ANSI C standard when feasible and desirable. Because the standard does not take into account the special needs of embedded systems, it is necessary to depart from the standard in some areas and desirable in others. The standard does not take into account important embedded systems issues such as read only memory and embedded assembly language. For this reason, practical compilers intended for embedded systems do not completely comply with the standard, but use it as a guide.

As an example of an addition, Dynamic C has a chaining mechanism to chain fragments of code from different subroutines to an arbitrary number of chains. This extension permits the use of not only initialized variables, but any arbitrary code to execute before a program starts execution in the main function.

As an example of a deletion, as of version 10.23 Dynamic C does not support block scope variables or bit fields. The development toolchain does not include a separate preprocessor and linker, which may complicate the process of porting existing programs to the compiler. As of version 10.64 block scope for variables is supported.

As an example of an inconsistency, Dynamic C implicitly treats all initialized global variables as if they were declared with the const qualifier. Furthermore, all const variables reside in flash memory. Earlier versions of Dynamic C did not check the use of the const keyword in parameters—it was possible to pass a const variable as a parameter to a function that did not expect it, potentially leading to attempts to write to flash memory. As of the latest version of Dynamic C, the compiler will produce an error when the user attempts to modify a const variable directly, and will produce a warning if the user discards the const qualifier when passing a parameter to a function.

Multitasking constructs

One noteworthy feature of Dynamic C is its inclusion of language constructs to simplify multitasking. These constructs, the costate statement and the slice statement, implement a form of cooperative and preemptive multitasking, respectively. As an example, consider the following program which flashes two LEDs with different frequencies:

voidmain(){while(1){// Create 2 costatements which will toggle our LEDs.costate{led1on();waitfor(DelayMs(100));led1off();waitfor(DelayMs(50));}costate{led2on();waitfor(DelayMs(200));led2off();waitfor(DelayMs(50));}}}

When this code is run, the first costatement will be executed, and the first LED will turn on. The costatement will then yield to the second statement while it waits for 100 milliseconds. The second costatement will execute in a similar manner. While both costatements are waiting for their time to elapse, the while loop will busy-wait, but this waiting time could potentially be used to perform other tasks. For more information, see the Dynamic C User's Manual.

See also

Related Research Articles

<span class="mw-page-title-main">Assembly language</span> Low-level programming language

In computer programming, assembly language, often referred to simply as assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported.

Forth is a procedural, concatenative, stack-oriented programming language and interactive integrated development environment designed by Charles H. "Chuck" Moore and first used by other programmers in 1970. Although not an acronym, the language's name in its early years was often spelled in all capital letters as FORTH. The FORTH-79 and FORTH-83 implementations, which were not written by Moore, became de facto standards, and an official technical standard of the language was published in 1994 as ANS Forth. A wide range of Forth derivatives existed before and after ANS Forth. The free and open-source software Gforth implementation is actively maintained, as are several commercially supported systems.

<span class="mw-page-title-main">Motorola 68000</span> Microprocessor

The Motorola 68000 is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector.

<span class="mw-page-title-main">Microcontroller</span> Small computer on a single integrated circuit

A microcontroller or microcontroller unit (MCU) is a small computer on a single integrated circuit. A microcontroller contains one or more CPUs along with memory and programmable input/output peripherals. Program memory in the form of NOR flash, OTP ROM or ferroelectric RAM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips.

<span class="mw-page-title-main">Zilog Z80</span> 8-bit microprocessor

The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975, before going on sale in July 1976. The processor is a software-compatible with the Intel 8080 but with several enhancements and at a lower price. Like the 8080, the Z80 was mainly aimed at embedded systems, but it became one of the most widely used CPUs in home computers of the late 1970s and early 1980s. The Zilog Z80 was also common in military applications, musical equipment, and coin-operated arcade games of the era, including Pac-Man.

<span class="mw-page-title-main">MCS-51</span> Single chip microcontroller series by Intel

The Intel MCS-51 is a single chip microcontroller (MCU) series developed by Intel in 1980 for use in embedded systems. The architect of the Intel MCS-51 instruction set was John H. Wharton. Intel's original versions were popular in the 1980s and early 1990s, and enhanced binary compatible derivatives remain popular today. It is a complex instruction set computer, but also has some of the features of RISC architectures, such as a large register set and register windows, and has separate memory spaces for program instructions and data.

<span class="mw-page-title-main">Zilog</span> American manufacturer of microprocessors

Zilog, Inc. is an American manufacturer of microprocessors and 8-bit and 16-bit microcontrollers. It is also a supplier of application-specific embedded system-on-chip (SoC) products.

<span class="mw-page-title-main">Bank switching</span> A technique to increase the amount of usable memory

Bank switching is a technique used in computer design to increase the amount of usable memory beyond the amount directly addressable by the processor instructions. It can be used to configure a system differently at different times; for example, a ROM required to start a system from diskette could be switched out when no longer needed. In video game systems, bank switching allowed larger games to be developed for play on existing consoles.

<span class="mw-page-title-main">Hitachi HD64180</span> Microprocessor

The HD64180 is a Z80-based embedded microprocessor developed by Hitachi with an integrated memory management unit (MMU) and on-chip peripherals. It appeared in 1985. The Hitachi HD64180 "Super Z80" was later licensed to Zilog and sold by them as the Z64180 and with some enhancements as the Zilog Z180.

A barrel processor is a CPU that switches between threads of execution on every cycle. This CPU design technique is also known as "interleaved" or "fine-grained" temporal multithreading. Unlike simultaneous multithreading in modern superscalar architectures, it generally does not allow execution of multiple instructions in one cycle.

<span class="mw-page-title-main">Cypress PSoC</span> Type of integrated circuit

PSoC is a family of microcontroller integrated circuits by Cypress Semiconductor. These chips include a CPU core and mixed-signal arrays of configurable integrated analog and digital peripherals.

RS08 is a family of 8-bit microcontrollers by NXP Semiconductors. Originally released by Freescale in 2006, the RS08 architecture is a reduced-resource version of the Freescale MC68HCS08 central processing unit (CPU), a member of the 6800 microprocessor family. It has been implemented in several microcontroller devices for embedded systems.

<span class="mw-page-title-main">Rabbit 2000</span>

The Rabbit 2000 is a high-performance 8-bit microcontroller designed by Rabbit Semiconductor for embedded system applications. Rabbit Semiconductor has been bought by Digi International, which is since selling the Rabbit microcontrollers and hardware based on them. The instruction set is based on the original Z80 microprocessor, but with some additions of new instructions as well as deletions of some instructions. Among the Z80 instructions missing in the Rabbit, cpir is particularly notable, since it allows for much more efficient implementations of some often-used standard C functions such as strlen, strnlen and memchr. According to the Rabbit documentation, it executes its instructions 5 times faster than the original Z80 microprocessor, that is, similarly to the Zilog eZ80.

TLCS is a prefix applied to microcontrollers made by Toshiba. The product line includes multiple families of CISC and RISC architectures. Individual components generally have a part number beginning with "TMP". E.g. the TMP8048AP is a member of the TLCS-48 family.

The Small Device C Compiler (SDCC) is a free-software, partially retargetable C compiler for 8-bit microcontrollers. It is distributed under the GNU General Public License. The package also contains an assembler, linker, simulator and debugger. As of March 2007, SDCC is the only open-source C compiler for Intel 8051-compatible microcontrollers. In 2011 the compiler was downloaded on average more than 200 times per day.

A modified Harvard architecture is a variation of the Harvard computer architecture that, unlike the pure Harvard architecture, allows memory that contains instructions to be accessed as data. Most modern computers that are documented as Harvard architecture are, in fact, modified Harvard architecture.

The 9S08 is an 8-bit microcontroller (µC) family originally produced by Motorola, later by Freescale Semiconductor, and currently by NXP, descended from the Motorola 6800 microprocessor. It is a CISC microcontroller. A slightly extended variant of the 68HC08, it shares upward compatibility with the aging 68HC05 microcontrollers, and is found in almost any type of embedded systems. The larger members offer up to 128 KiB of flash, and 8 KiB of RAM via a simple memory management unit (MMU) which allows bank-switching 16 KiB of the address space and an address/data register pair which allows data fetches from any address. The paging scheme used allows for a theoretical maximum of 4 MB of flash.

In computer programming, a constant is a value that is not altered by the program during normal execution. When associated with an identifier, a constant is said to be "named," although the terms "constant" and "named constant" are often used interchangeably. This is contrasted with a variable, which is an identifier with a value that can be changed during normal execution. To simplify, constants' values remains, while the values of variables varies, both hence their names. where as the constant variable of variation is the number that results two variables.

RL78 Family is a 16-bit CPU core for embedded microcontrollers of Renesas Electronics introduced in 2010.

References

  1. Digi International Acquires Rabbit Semiconductor Archived 2009-02-13 at the Wayback Machine
  2. "Control Engineering | Digi purchases Rabbit Semiconductor for $49 million". Control Engineering. 2005-06-07. Retrieved 2022-07-06.
  3. "Rabbit | Digi International". www.digi.com.
  4. Jean J. Labrosse. "Embedded Software: Know It All". 2007. p. 246.
  5. "Dynamic C 10: for Rabbit-based embedded systems".