This article needs additional citations for verification .(October 2008) |
Industry | microcontrollers |
---|---|
Founded | 1983 |
Headquarters | , |
Owner | Digi International |
Website | www |
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.
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.
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]
This article may be too technical for most readers to understand.(May 2024) |
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]
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.
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.
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.
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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.
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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.
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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.
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