168 lines
9.5 KiB
HTML
168 lines
9.5 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html><head>
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<meta content="text/html; charset=ISO-8859-1" http-equiv="content-type">
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<title>ChibiOS/RT embedded RTOS homepage</title></head>
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<body>
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<table style="text-align: left; width: 100%;" border="0" cellpadding="2" cellspacing="2">
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<tbody>
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<tr align="center">
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<td colspan="2" rowspan="1">
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<h2>ChibiOS/RT embedded RTOS homepage</h2>
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</td>
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</tr>
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<tr>
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<td style="text-align: center; vertical-align: top; width: 150px;">Current
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Version 0.8.2<br>
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-<br>
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<a href="http://sourceforge.net/projects/chibios/" rel="me" target="_top">Project on SourceForge</a><br>
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<a href="html/index.html" target="_top" rel="me">Documentation</a><br>
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<a href="http://sourceforge.net/project/showfiles.php?group_id=205897" rel="me" target="_top">Downloads</a><br><a href="http://wiki.mechlab.net/doku.php?id=chibios:start" rel="me" target="_top">Wiki</a><br><a href="http://sourceforge.net/forum/?group_id=205897" rel="me" target="_top">Forum</a><br>
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<a href="http://sourceforge.net/users/gdisirio/" rel="me" target="_top">Contact me</a><br>
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-<br>
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<a href="#History">History</a><br>
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<a href="#Description">Description</a><br><a href="index.html#Current_ports">Current ports</a><br>
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<a href="#Design">Design</a><br><a href="#Performance_and_Size">Performance and Size</a><br>
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<a href="#Future">Future</a><br>
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-<br>
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<a href="#Credits">Credits</a><br>
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<br>
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<a href="http://sourceforge.net"><img src="http://sflogo.sourceforge.net/sflogo.php?group_id=205897&type=4" alt="SourceForge.net Logo" border="0" height="37" width="125"></a><br>
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<br>
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<a href="http://sourceforge.net/donate/index.php?group_id=205897"><img src="http://images.sourceforge.net/images/project-support.jpg" alt="Support This Project" border="0" height="32" width="88"></a><br><br>
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<!-- Inizio Codice Shinystat -->
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<script type="text/javascript" language="JavaScript" src="http://codice.shinystat.com/cgi-bin/getcod.cgi?USER=ChibiOS"></script>
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<noscript>
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<a href="http://www.shinystat.com/it" target="_top">
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<img src="http://www.shinystat.com/cgi-bin/shinystat.cgi?USER=ChibiOS" alt="Statistiche" border="0"></a>
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</noscript>
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<!-- Fine Codice Shinystat -->
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</td>
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<td style="text-align: justify; vertical-align: top;">
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<h3><a name="History"></a>History</h3>
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This RTOS is something I wrote back in 1990 for use on boards
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equipped
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with M68K processors, the development was made on an Atari ST. The OS
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worked well for its intended purpose, Internet was not
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widespread at that time so the system had a limited use.<br>
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Recently I decided to release this system, formerly known as <span style="font-style: italic;">mkRTOS</span>, as Free
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Software. I cleaned up the code, improved the documentation, made a
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port on a more modern architecture (ARM) and it is finally ready.<br>
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While ChibiOS/RT is a new product it is based on a proven system so the
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alpha/beta phases should not last long, the project was started as an
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alpha
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version mainly to be able to incorporate the feedback into the
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product easily.<br>
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<h3><a name="Description"></a>Description</h3>
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ChibiOS/RT is designed for embedded applications and it is meant to be
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linked with the application code. The design philosophy is to make it
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easy to use so I hope that all the APIs are meaningful, easy to
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understand and with the parameters you would expect from them.<br>The
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system offers threads, semaphores, mutexes, messages, events, virtual
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timers,
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queues, I/O channels with timeout capability and much more. The
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Priority Inheritance algorithm is implemented through the Mutexes
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mechaninsm, the implementation supports any number of threads and
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nested mutexes.<br>
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<h3><a name="Current_ports"></a>Current
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ports</h3>
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Currently the ChibiOS/RT is ported to the following architectures:<br>
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<ul>
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<li>ARM7TDMI-LPC214x, the port to other LPC2000 chips
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should be trivial. Both ARM and THUMB modes are supported.</li>
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<li>ARM7TDMI-AT91SAM7X256, this port also supports other Atmel
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chips: SAM7XC, SAM7S and the various sizes (128, 256, 512) with
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minimal changes.</li>
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<li>ARM Cortex-M3, ST Microelectronics STM32.</li>
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<li>Atmel AVR: AT90CAN128 and ATmega128 demos included.</li>
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<li>Texas Instruments MSP430, complete but untested.</li>
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<li>x86 as a Win32 process, this port allows to write
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your application on the PC without the need of a development
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board/simulator/emulator. Communication ports are simulated over
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sockets, you can telnet on the simulator ports for the debug. I am
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considering to create a similar simulator into a Linux process.</li>
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<li>M68K, this was the original target but it is
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currently removed from the source tree because currently I have no way
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to test it, my old Atari ST is long dead. It should be very easy to
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revive the port to the M68K or Coldfire CPUs.</li>
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</ul>
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In general the port is very easy on architectures that can handle well
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linked lists, the kernel is entirely reliant on lists so this
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is a
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very important efficiency factor. 16 and 32 bits architectures are
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always fine, 8 bit architectures should be evaluated case by case but
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are not ruled out, something like an H8 would not have problems. You
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could port it
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to a Z80/Z180 (I considered that too, and made tests using the SDCC
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compiler) but the
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resulting code is not much efficient because the instruction set is
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missing the indirect addressing for 16 bits values that is important
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for efficient linked lists traversal.
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<h3><a name="Design"></a>Design</h3>
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The system was designed to be stable and avoid trouble as much as
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possible so some rules were set:<br>
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<ul>
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<li>No arrays or tables, I don't like to have to
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configure limits
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for data structures, only use lists or other dynamic data structures.
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See
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the <a href="http://chibios.sourceforge.net/html/index.html" target="_top" rel="me">Documentation</a> and
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the demos.</li>
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<li>No memory allocation inside the kernel, an allocator
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can be
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troublesome for RT applications. All the data structures are declared
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in the application code and not allocated from a shared system heap.
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This does not prevent the application code to use an allocator if
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needed, it is just the kernel that does not require it.</li>
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<li>No weird macros in the user code, everything should
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look
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and feel like normal C code with a normal main() function. I don't like
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to bring someone else weird programming habits in my code and I think
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this is true for everybody.</li>
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<li>Encapsulate all the things that need changes while
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porting
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the OS to new architectures in few template files, fill the code into
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the templates and the port is done.</li></ul><h3><a name="Performance_and_Size"></a>Performance and Size</h3>ChibiOS/RT
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has a wide set of APIs but all the subsystems can be included or
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removed from the memory image by editing the kernel configuration file
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chconf.h. On ARM processors, the kernel size starts at just
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1.5KiB depending on the included subsystems and the choosen
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compiler optimizations.<br>As reference, a kernel configured with...<br><ul><li>System startup code</li><li>Chip initialization code</li><li>Multithreading APIs</li><li>Virtual Timer APIs</li><li>Semaphore APIs</li><li>System time + Sleep API</li><li>Suspend/Resume APIs</li><li>Small main() program with flashing LEDs demo and 3 threads</li></ul>...just takes 2.11KiB of program space when compiled using THUMB code and space optimizations. Note that this is quite a <span style="font-weight: bold;">typical configuration</span>
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not a minimal one. A kernel configured with all the options and
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optimized for speed takes about 6KiB. See the documentation about the
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many available subsystems.<br><br>About performance, on a 48MHz LPC
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ARM7 processor the kernel is capable of context switch time ranging
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from 3 to 6 microseconds depending on the code type (ARM/THUMB) and the
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choosen compiler/kernel optimizations. In the distribution is included
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a spreadsheet with the exact values and the various space/time trade
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offs.<br>The context switch time is *measured* using 2 threads
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exchanging messages and doing *real* work, it is not a calculated peak
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value. See the demo code, it includes the benchmark.
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<h3><a name="Future"></a>Future</h3>
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Expect:<br><ul>
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<li>Documentation improvements.</li>
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<li>Ports to more architectures/boards when I am able to
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put my hands on new hardware/tools.</li>
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<li>More demos.</li>
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<li>Creation of new subsystems.</li>
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<li>Integration with
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existing other free projects like: TCP/IP stacks, File Systems etc.</li>
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</ul>
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<h3><a name="Credits"></a>Credits</h3>
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ChibiOS/RT was created using:<br>
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<ul>
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<li>7-Zip, <a href="http://7-zip.org" target="_top">http://7-zip.org</a></li>
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<li>GCC and GNU binutils, <a href="http://gcc.gnu.org" target="_top">http://gcc.gnu.org</a></li>
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<li>Doxigen, <a href="http://www.doxygen.org" target="_top">http://www.doxygen.org</a></li>
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<li>Inkscape, <a href="http://www.inkscape.org" target="_top">http://www.inkscape.org</a></li>
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<li>MinGW, <a href="http://mingw.org" target="_top">http://mingw.org</a></li>
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<li>NVU, <a href="http://www.nvu.com/" target="_top">http://www.nvu.com</a></li>
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<li>YAGARTO, <a href="http://www.yagarto.de" target="_top">http://www.yagarto.de</a></li>
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</ul>
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</td>
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</tr>
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</tbody>
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</table>
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</body></html> |