📄 introduction_to_embedded_systems.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html><head> <title></title> <link rel="stylesheet" media="screen" type="text/css" href="./style.css" /> <link rel="stylesheet" media="screen" type="text/css" href="./design.css" /> <link rel="stylesheet" media="print" type="text/css" href="./print.css" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /></head><body><a href=start.html>start</a></br><div class="toc"><div class="tocheader toctoggle" id="toc__header">Table of Contents</div><div id="toc__inside"><ul class="toc"><li class="clear"><ul class="toc"><li class="level2"><div class="li"><span class="li"><a href="#introduction_to_embedded_systems" class="toc">Introduction to Embedded Systems</a></span></div><ul class="toc"><li class="level3"><div class="li"><span class="li"><a href="#basic_concepts" class="toc">Basic Concepts</a></span></div></li><li class="level3"><div class="li"><span class="li"><a href="#overview_of_the_development_environment" class="toc">Overview of the Development Environment</a></span></div></li><li class="level3"><div class="li"><span class="li"><a href="#quick_start" class="toc">Quick Start</a></span></div></li></ul></li></ul></li></ul></div></div><h2><a name="introduction_to_embedded_systems" id="introduction_to_embedded_systems">Introduction to Embedded Systems</a></h2><div class="level2"></div><!-- SECTION [1-43] --><h3><a name="basic_concepts" id="basic_concepts">Basic Concepts</a></h3><div class="level3"><p>This course explores embedded system development on the BF533 STAMP. The STAMP as used in this course has uClinux as its resident operating system (<acronym title="Operating System">OS</acronym>). This is a stripped down Linux appropriate for embedded systems. Our particular version is for the Analog Devices ADSP-BF533 Blackfin. </p><p>The course is intended for those who are familiar with the C programming language, the Linux <acronym title="Operating System">OS</acronym>, and who have interest in learning about embedded systems development. The course is less appropriate for embedded systems gurus; although, the early portion of the course can serve to introduce the STAMP/uClinux target. </p><p>The course is organized as a hands on experience and the participants will: </p><ul><li class="level1"><div class="li">learn how to set up and configure the system</div></li><li class="level1"><div class="li">learn what resources are available</div></li><li class="level1"><div class="li">learn to use a selection of the available resources</div></li></ul></div><!-- SECTION [44-899] --><h3><a name="overview_of_the_development_environment" id="overview_of_the_development_environment">Overview of the Development Environment</a></h3><div class="level3"><p>The development environment consists of these elements </p><ul><li class="level1"><div class="li">the target hardware and its resident software</div></li><li class="level1"><div class="li">the development workstation</div></li><li class="level1"><div class="li">the interconnection between these two machines</div></li></ul><p>Let’s look at each of these elements, in turn, starting with the target. The target hardware for this course is the STAMP, a processor board with various resources. For our discussion at this point, we just mention a few: </p><ul><li class="level1"><div class="li">an Ethernet controller (with RJ45 Ethernet jack (female))</div></li><li class="level1"><div class="li">a serial port (with DB9 serial connector (female))</div></li><li class="level1"><div class="li">a resident <acronym title="Operating System">OS</acronym>, uClinux</div></li><li class="level1"><div class="li">a power jack and on board voltage regulator (7V-20V DC input)</div></li></ul><p>The second element of the development environment is the workstation. It is essentially a linux box which should have </p><ul><li class="level1"><div class="li">an available serial port</div></li><li class="level1"><div class="li">terminal emulator software (minicom is included in most Linux distributions)</div></li><li class="level1"><div class="li">an Ethernet card</div></li><li class="level1"><div class="li">a CD ROM reader</div></li></ul><p>This is, then, a rather typical Linux box. The CD ROM capability is needed to access the files which come on a CD shipped with the STAMP board. This contains the development tools, called tool chains. Note that it will be typical (but not necessary) that the workstation has an Intel derived CPU. In our case the target will be the Analog Devices Blackfin ADSP BF533 Processor, definitely not Intel. Hence, the toolchains comprise a cross compilation tool set. It is of particular interest that the target <acronym title="Operating System">OS</acronym> is Linux, as is that of the development workstation, despite the different CPU’s. Of course, the target <acronym title="Operating System">OS</acronym> is a very stripped down Linux. The virtue of the open source nature of Linux is apparent - it can be modified appropriately for its host. The third and last element of the development environment is the interconnection between the workstation and the target. There are potentially two such connections: </p><ul><li class="level1"><div class="li">the RS232 serial connection</div></li><li class="level1"><div class="li">the 10 Mbps Ethernet connection</div></li></ul><p>Let’s consider the serial connection. The workstation, running a terminal emulator (we later assume minicom), becomes the target’s terminal. When power is applied (or the STAMP reset button pressed) the STAMP boots into the ‘Bootloader’, essentially a system monitor with a set of commands to which it will respond. Among these commands, available before booting into uClinux, are: </p><ul><li class="level1"><div class="li">a command to upload a new uClinux image from the workstation to the target’s RAM</div></li><li class="level1"><div class="li">a command to write the RAM image into FLASH ROM</div></li><li class="level1"><div class="li">a command to boot the uClinux image in the FLASH ROM</div></li><li class="level1"><div class="li">an alternative command to boot an image in RAM</div></li></ul><p>At the completion of the boot/initialization of uClinux it presents a login prompt. In summary, the workstation can issue commands to the Bootloader and, once uClinux boots, the workstation becomes the Linux terminal. During or subsequent to the uClinux boot, the Ethernet capability is brought up. The appropriate work area on the workstation can be mounted via nfs, integrating that work area with the uClinux file hierarchy. </p></div><!-- SECTION [900-3882] --><h3><a name="quick_start" id="quick_start">Quick Start</a></h3><div class="level3"><p>Upon getting a system, many of us want to get it up and running immediately, despite not understanding all the relevant details. That is the purpose of this section. Here we intend to configure and deploy the three elements of our development system. Recall that these elements are </p><ul><li class="level1"><div class="li">the Linux workstation</div></li><li class="level1"><div class="li">the STAMP target</div></li><li class="level1"><div class="li">the interconnection of those machines -RS232 serial, Ethernet</div></li></ul><p>We’ll discuss these elements throughout this chapter and end up with a development environment that is ready for productive work. Note that there are relevant, useful (somewhat interrelated) web sites supporting this setup: </p><ul><li class="level1"><div class="li"><a href="http://www.uClinux.org/" class="urlextern" title="http://www.uClinux.org/" rel="nofollow">http://www.uClinux.org</a></div></li><li class="level1"><div class="li"><a href="http://blackfin.uClinux.org" class="urlextern" title="http://blackfin.uClinux.org" rel="nofollow">http://blackfin.uClinux.org</a></div></li></ul></div><h4><a name="connecting_the_hardware" id="connecting_the_hardware">Connecting the Hardware</a></h4><div class="level4"><p>1. Connect the serial port to your host computer from the STAMP board. </p><p>2. Connect the Ethernet cable to your local network from the STAMP board.</p><p>3. Start a terminal emulation program (Minicom or HyperTerminal) on your host computer. From the configuration menu set the serial port connection for: </p><ul><li class="level1"><div class="li">57600 baud </div></li><li class="level1"><div class="li">8 data bits</div></li><li class="level1"><div class="li">parity none </div></li><li class="level1"><div class="li">1 stop bit</div></li><li class="level1"><div class="li">h/w flow control off</div></li></ul><p>4. Connect the DC power input and power up the board. </p><p>5. After the STAMP board powers up you should see a U-Boot start-up screen on your terminal window. At this stage if you allow the boot timer to count down the board will load the uClinux kernel out of flash and boot the kernel and you will be brought to the command shell.</p><p>Troubleshooting: If you don’t see any text on the screen make sure that you have properly connected power to the board (the power LED should be on) and make sure a correct straight through serial cable is being used. If the screen text is corrupted, check the serial port connection baud rate settings.</p></div><h4><a name="installing_the_gnu_linux_toolchain" id="installing_the_gnu_linux_toolchain">Installing the GNU/Linux Toolchain</a></h4><div class="level4"><p>1. Install the binutils and GCC tools on your machine (as root): <br/></p><pre class="code">bash# rpm -ivh bfin-elf-3.4-beta.i386.rpm</pre><p> 2. In user mode export the path for the tools <br/></p><pre class="code">bash> export PATH=/opt/uClinux/bfin/bin:$PATH</pre><p> </p><p> The toolchain can also be compiled from source by executing the build script that is located in the scripts directory. Extract all of the files to a local directory as well as the build script and modify the script to point to your directory structure. After the script has executed, export the path to point to your new tool chain output directory.</p></div><h4><a name="installing_the_ucinux_kernel" id="installing_the_ucinux_kernel">Installing the uCinux Kernel</a></h4><div class="level4"><ol><li class="level1"><div class="li"> Copy the kernel source to your work directory</div></li><li class="level1"><div class="li"> Uncompress the kernel:<br/></div></li></ol><pre class="code">bunzip2 uClinux-dist.tar.bz2tar -xvf uClinux-dist.tar</pre><p> Now that the kernel is uncompressed in the work directory you are now ready to start building your own uClinux kernel for the Blackfin processor.</p></div><!-- SECTION [3883-] --></body></html>⌨️ 快捷键说明
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