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<ol class="chapter"><li class="affix"><a href="../index.html">Introduction</a></li><li class="affix"><a href="../background/index.html">Background</a></li><li class="affix"><a href="../requirements/index.html">Requirements</a></li><li><a href="../hardware/index.html"><strong aria-hidden="true">1.</strong> Meet your hardware</a></li><li><a href="../setup/index.html"><strong aria-hidden="true">2.</strong> Development environment setup</a></li><li><ol class="section"><li><a href="../setup/LINUX.html"><strong aria-hidden="true">2.1.</strong> Linux</a></li><li><a href="../setup/WINDOWS.html"><strong aria-hidden="true">2.2.</strong> Windows</a></li><li><a href="../setup/MACOS.html"><strong aria-hidden="true">2.3.</strong> macOS</a></li><li><a href="../setup/VERIFY.html"><strong aria-hidden="true">2.4.</strong> Verify the installation</a></li></ol></li><li><a href="../getting-started/00.00.README.html"><strong aria-hidden="true">3.</strong> Getting started</a></li><li><ol class="section"><li><a href="../getting-started/01.00.BUILD.html"><strong aria-hidden="true">3.1.</strong> Building</a></li><li><a href="../getting-started/02.00.FLASH.html"><strong aria-hidden="true">3.2.</strong> Flashing</a></li><li><a href="../getting-started/03.00.DEBUG.html"><strong aria-hidden="true">3.3.</strong> Debugging</a></li><li><a href="../getting-started/04.00.SOLUTION.html"><strong aria-hidden="true">3.4.</strong> Solution</a></li></ol></li><li><a href="../hello-world/00.00.README.html"><strong aria-hidden="true">4.</strong> Hello world</a></li><li><ol class="section"><li><a href="../hello-world/01.00.SEMIHOSTING.html"><strong aria-hidden="true">4.1.</strong> Semihosting</a></li><li><a href="../hello-world/02.00.UART.html"><strong aria-hidden="true">4.2.</strong> Serial communication</a></li><li><ol class="section"><li><a href="../hello-world/02.01.NIX.html"><strong aria-hidden="true">4.2.1.</strong> *nix</a></li><li><a href="../hello-world/02.02.WINDOWS.html"><strong aria-hidden="true">4.2.2.</strong> Windows</a></li></ol></li><li><a href="../hello-world/03.00.LED.html"><strong aria-hidden="true">4.3.</strong> GPIO and LEDs</a></li><li><ol class="section"><li><a href="../hello-world/03.01.SOLUTION.html"><strong aria-hidden="true">4.3.1.</strong> Solution</a></li></ol></li></ol></li><li><a href="../choice/00.00.README.html"><strong aria-hidden="true">5.</strong> Choose Your Own Adventure</a></li><li><a href="../microbit/00.00.README.html"><strong aria-hidden="true">6.</strong> micro:bit HAL basics</a></li><li><ol class="section"><li><a href="../microbit/01.00.BUTTONS.html"><strong aria-hidden="true">6.1.</strong> Buttons</a></li><li><a href="../microbit/02.00.DELAY.html"><strong aria-hidden="true">6.2.</strong> Delays</a></li><li><a href="../microbit/03.00.DISPLAY.html"><strong aria-hidden="true">6.3.</strong> Display</a></li></ol></li><li><a href="../serial/00.00.README.html"><strong aria-hidden="true">7.</strong> Serial UART - Blocking</a></li><li><ol class="section"><li><a href="../serial/01.00.ECHO.html" class="active"><strong aria-hidden="true">7.1.</strong> Echo Server</a></li><li><ol class="section"><li><a href="../serial/01.01.THEORY.html"><strong aria-hidden="true">7.1.1.</strong> Theory</a></li><li><a href="../serial/01.02.ECHO.html"><strong aria-hidden="true">7.1.2.</strong> Solution</a></li></ol></li><li><a href="../serial/02.00.html"><strong aria-hidden="true">7.2.</strong> Exercises</a></li><li><ol class="section"><li><a href="../serial/02.01.html"><strong aria-hidden="true">7.2.1.</strong> Reverse echo</a></li><li><ol class="section"><li><a href="../serial/02.01.SOLUTION.html"><strong aria-hidden="true">7.2.1.1.</strong> Solution</a></li></ol></li><li><a href="../serial/02.02.html"><strong aria-hidden="true">7.2.2.</strong> Countdown</a></li><li><ol class="section"><li><a href="../serial/02.02.SOLUTION.html"><strong aria-hidden="true">7.2.2.1.</strong> Solution</a></li></ol></li><li><a href="../serial/02.04.html"><strong aria-hidden="true">7.2.3.</strong> Quiz</a></li><li><ol class="section"><li><a href="../serial/02.04.SOLUTION.html"><strong aria-hidden="true">7.2.3.1.</strong> Solution</a></li></ol></li></ol></li></ol></li><li><a href="../display/00.00.README.html"><strong aria-hidden="true">8.</strong> LED display</a></li><li><ol class="section"><li><a href="../display/01.00.THEORY.html"><strong aria-hidden="true">8.1.</strong> Theory</a></li><li><a href="../display/02.00.PROBLEM.html"><strong aria-hidden="true">8.2.</strong> Problem</a></li><li><ol class="section"><li><a href="../display/02.01.LAYOUT.html"><strong aria-hidden="true">8.2.1.</strong> Layout</a></li><li><a href="../display/02.02.DELAY.html"><strong aria-hidden="true">8.2.2.</strong> Delays</a></li><li><a href="../display/02.03.MULT.html"><strong aria-hidden="true">8.2.3.</strong> Multiplexing</a></li></ol></li><li><a href="../display/03.00.SOLUTION.html"><strong aria-hidden="true">8.3.</strong> Solution</a></li><li><ol class="section"><li><a href="../display/03.01.LAYOUT.html"><strong aria-hidden="true">8.3.1.</strong> Layout</a></li><li><a href="../display/03.02.MULT.html"><strong aria-hidden="true">8.3.2.</strong> Multiplexing</a></li><li><a href="../display/03.03.FULL.html"><strong aria-hidden="true">8.3.3.</strong> Full Solution</a></li></ol></li></ol></li><li><a href="../sensors/00.00.README.html"><strong aria-hidden="true">9.</strong> WIP - Sensors and I²C</a></li><li><a href="../nb/00.00.README.html"><strong aria-hidden="true">10.</strong> WIP - Non-blocking</a></li><li><a href="../nb/00.00.README.html"><strong aria-hidden="true">11.</strong> WIP - Interrupts</a></li><li><a href="../rtfm/00.00.README.html"><strong aria-hidden="true">12.</strong> WIP - Real time</a></li><li><a href="../hal/00.00.README.html"><strong aria-hidden="true">13.</strong> WIP - Creating a HAL</a></li><li class="affix"><a href="../appendix/explore.html">Explore</a></li><li class="affix"><a href="../appendix/gdb.html">GDB cheatsheet</a></li><li class="affix"><a href="../appendix/troubleshooting.html">General troubleshooting</a></li></ol>
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<h1 class="menu-title">MicroRust</h1>
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<main>
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<a class="header" href="#echo-server" id="echo-server"><h1>Echo Server</h1></a>
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<p>An echo server, is probably the simplest server we could make.
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It should receive a message, and echo it back to the sender.</p>
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<p>We earlier said that minicom/PuTTY would transmit any keystrokes we send,
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and display and data received,
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so the end result should be the familiar experience of typing and seeing the letters typed appear as expected.</p>
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<a class="header" href="#flow" id="flow"><h2>Flow</h2></a>
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<ol>
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<li>The character <code>a</code> is typed</li>
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<li>minicom/PuTTY encodes the <code>a</code> character's unicode code point (<code>097</code> in decimal) as a word in a serial frame</li>
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<li>The frame is transmitted to the micro:bit over USB</li>
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<li>The micro:bit software decodes the frame to get the word</li>
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<li>The microbit software re-encodes the word to get a (new but identical) frame</li>
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<li>The frame is transmitted to the computer over USB</li>
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<li>minicom/PuTTY decodes the frame's word as a unicode code point</li>
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<li>The letter <code>a</code> is displayed</li>
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