http://armpit.sourceforge.net/
A Scheme Interpreter for ARM Microcontrollers
ARMPIT SCHEME is an interpreter for the Scheme language
(lexically-scoped dialect of Lisp) that
runs on RISC microcontrollers with ARM core. It
is based on the description in the
Revised^5
Report on the Algorithmic Language Scheme (r5rs),
with some extensions (for I/O) and some omissions (to fit within MCU
memory).
It is further designed to support multitasking and multiprocessing.
Armpit Scheme is expected to be well suited to educational settings,
including student projects in
courses on control and
instrumentation, or capstone design courses where microcontrollers are
needed.
It is meant to enrich the spectrum of interpreted languages available
for MCUs (eg. BASIC and FORTH)
and can be an alternative to MCU-based bytecode interpreters (eg. for
Scheme or Java) and to compiled
languages (eg. C).
The name "Armpit" was selected for this project because it includes
"ARM" (as in ARM core MCU) and "pit" (as in kernel, noyau, the core of
an Operating System (OS)). Armpit Scheme, once loaded, governs the
operation of the MCU, and is "Scheme to the metal"
in the sense of running without any other OS. It may be thought of as
turning the MCU into a rudimentary Scheme machine.
The screenshot below shows the system running on a NewMicros Tiny2106
board. Minicom is used to communicate with the board which reads,
evaluates and prints the result of
the entered expressions.
The number in front of the "armpit>" prompt indicates the number of
bytes of heap space that
remain available.
Figure 1: Sample Interaction with Armpit Scheme
The latest development snapshot of Armpit Scheme is 00.0215
and
the current stable version is 00.0160.
Both are distributed under the MIT License and are
beta releases with both known bugs and unknown bugs.
The source code, and pre-assembled (ready-to-upload) Intel Hex and
binary image files,
can be downloaded from the armpit project summary
page
or the download
site at SourceForge.
Alternatively, you can view and download the
source code from
your web browser.
The system is documented in several web pages:
- Documentation for Armpit Scheme Snapshot 00.0215:
- Documentation for Armpit Scheme Snapshot 00.0186:
- Documentation for Armpit Scheme Snapshot 00.0171:
- Documentation for Armpit Scheme Version 00.0160:
- Documentation for prior
snapshots and versions of Armpit Scheme.
- How
To: upload, communicate with and re-assemble Armpit Scheme, and
some additional notes.
It is designed to run on the following boards:
Table 1: Armpit Scheme Development MCU Board Specifications
(*) USB is not implemented in the Armpit Scheme core for these 4 MCUs.
On-board LCDs / OLEDs are programmed from within user space (not in the
core).
The BeagleBoard has 256MB of Flash but only 32MB are used for Armpit
Scheme user files (the file Flash
is shadowed by 32MB of SDRAM).
External links of potential interest include:
- Discussions on the potential of Scheme/Lisp for Microcontrollers:
A brief essay on embedded
lisps and schemes by Matt Knox. A colorful project on wearable lisp and
unsorted discussions or comments about the potential for Lisp/Scheme to
run on MCUs (1),
(2), (3), (4),
(5),
(6)
(search for LISP or Scheme in those pages). A Scheme byte-code
interpreter that runs on PIC MCUs (named BIT and PICBIT
by Danny Dube and Marc Feeley of the
University of Montreal. The
LegoScheme project at Indiana University. XS LISP for
the LEGO RCX by Taiichi Yuasa.
- Implementations of Scheme/Lisp on the metal, in assembly or
small: The movitz
project that targets Lisp "on the metal" (x86). Dream scheme
written in PPC/x86 assembly language by David Joseph Stith. A scheme
in forth by Mark Probst. TinyScheme by
Dimitrios Souflis and Jonathan S. Shapiro (with versions for ARM
processors). pocket
scheme (for PDAs) by Ben Goetter. Hedgehog embedded
LISP by Lars Wirzenius and Kenneth Oksanen.
- Other interesting functional language systems running on the
metal: The Python-on-a-Chip
project where the PyMite VM is implemented on microcontrollers. The eLua project where Lua
is implemented on microcontrollers. The lispm
project where LISP is implemented in an FPGA.
- Multiprocessing Scheme systems: Termite
Scheme, a distributed scheme using Erlang-like communication (paper).
Kali Scheme, a
distributed implementation based on Scheme48, that is undergoing a revival. The
Tube, a system for Flexible Distributed Programming using Mobile
Code, in scheme.
- Web Sites Discussing Scheme in Action, Research and Education:
The website of schemers.org. A bibliography of scheme research.
A list of schools
that use Scheme in their curricula (from Schemers Inc.).
- Online Books on Scheme:
Teach Yourself Scheme in Fixnum Days by Dorai Sitaram. The Scheme Programming Language
by R. Kent Dybvig. Structure
and Interpretation of Computer Programs by Harold Abelson, Gerald
Jay Sussman and Julie Sussman. How to
Design Programs by Matthias Felleisen, Robert B. Findler, Matthew
Flatt and Shriram Krishnamurthi.
Acknowledgment and Disclaimer
Armpit Scheme is presently developed at the
Fischell Department of Bioengineering
of the A.J. Clark School of Engineering at the University of Maryland
at College Park.
Part of its development (until 02/07)
was based upon work supported by the National Science Foundation under
Grant
No. 0134424. Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s) and do not
necessarily
reflect the views of the Department, School, University or of the
National Science Foundation.
Last updated December 28, 2009
bioe-hubert-at-sourceforge.net
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