791 lines
25 KiB
HTML
791 lines
25 KiB
HTML
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<title>Fomu: An FPGA in your USB Port</title>
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<meta name="description" content="A framework for easily creating beautiful presentations using HTML">
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<meta name="author" content="Sean "xobs" Cross">
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<![endif]-->
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<style>
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/*********************************************
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* ZOOM REVERSE TRANSITION (i.e. zoom out)
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*********************************************/
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.reveal .slides section[data-transition=zoomrev],
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</head>
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<body>
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<!-- Start of main presentation -->
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<div class="reveal">
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<div class="footer">
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<a class="url" href="https://p.xobs.io/td19/">p.xobs.io/td19</a>
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<span class="theme">Teardown 2019</span><span class="hashtag"> | #teardown</span><span class="twitter"> |
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@crowd_supply</span>
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</div>
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<div class="slides">
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<section>
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<h2>Fomu: an FPGA in your USB Port</h2>
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<img src="img/tomu-fomu-case-superwide.jpg">
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<p>
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Pre-order now on Crowd Supply! <a href="https://t.xobs.io/fomu">t.xobs.io/fomu</a>
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</p>
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</section>
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<section data-background-image="css/theme/teardown2019-title-bg-transparent.svg">
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<h1>Fomu: An FPGA in your USB Port</h1>
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<h4>A whirlwind introduction to Fomu; a workshop in three levels</h4>
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<p align="right">
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<small>Sean Cross - <a href="https://xobs.io/">https://xobs.io/</a> - @xobs</small>
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</p>
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</section>
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<section>
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<h2>Levels of Fomu</h2>
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<p>
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Fomu aims to be accessable on three levels:
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<ol>
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<li>Python / Interpreter</li>
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<li>RISC-V / C</li>
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<li>FPGA / HDL</li>
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</ol>
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</p>
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</section>
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<section>
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<h2>Workshop Outline</h2>
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<ol>
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<li>What do I need to get started?</li>
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<li>What is an FPGA, and what is Fomu?</li>
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<li>Working with Fomu using Python, RISC-V, and HDL</li>
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</ol>
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</section>
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<section>
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<section>
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<h2>What do I need to get started?</h2>
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<ol>
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<li>DFU utilities</li>
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<li>Serial console</li>
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<li>RISC-V toolchain</li>
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<li>Synthesis</li>
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<li>Place-and-Route</li>
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<li>Packer</li>
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<li>Python 3</li>
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</ol>
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</section>
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</section>
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<section>
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<section>
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<h2>What is an FPGA?</h2>
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<img data-src="img/ice40-lut.png" alt="SB_LUT4">
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<!--
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<p>
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An FPGA is a chip that executes logic.
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</p>
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<p>
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FPGAs are measured in resources called LUTs or LCs.
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</p>
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-->
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</section>
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<section>
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<h2>What is an FPGA?</h2>
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<table style="transform: scale(.80) translate(-15%)">
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<tr>
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<th></th>
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<th>0</th>
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<th>1</th>
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<th>2</th>
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<th>3</th>
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<th>4</th>
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<th>5</th>
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<th>6</th>
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<th>7</th>
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<th>8</th>
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<th>9</th>
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<th>10</th>
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<th>11</th>
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<th>12</th>
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<th>13</th>
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<th>14</th>
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<th>15</th>
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</tr>
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<tr>
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<td>IO0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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</tr>
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<tr>
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<td>IO1</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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<td>1</td>
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</tr>
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<tr>
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<td>IO2</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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<td>0</td>
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<td>0</td>
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<td>1</td>
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<td>1</td>
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</tr>
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<tr>
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<td>IO3</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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<td>0</td>
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<td>1</td>
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</tr>
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<tr>
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<td>O</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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<td>?</td>
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</tr>
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</table>
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</section>
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<section>
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<h2>What is an FPGA?</h2>
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<pre><code class="verilog" data-trim>
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module example (output reg [0:5] Q, input C);
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reg [0:8] counter;
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always @(posedge C)
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begin
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counter <= counter + 1'b1;
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Q = counter[7] ^ counter[5] | counter<<2;
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end
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endmodule
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</code></pre>
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<img class="fragment" data-src="img/verilog-synthesis.png" alt="Verilog Synthesis">
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</section>
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<section>
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<h2>About the ICE40UP5K</h2>
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<ol>
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<li>5280 4-input LUTs (LC)</li>
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<li>16 kilobytes BRAM</li>
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<li class="fragment highlight-blue">128 kilobytes "SPRAM"</li>
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<li>Current-limited 3-channel LED driver</li>
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<li>2x I2C and 2x SPI</li>
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<li>8 16-bit DSP units</li>
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<li class="fragment highlight-blue">Warmboot capability</li>
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<li class="fragment highlight-blue">Open toolchain</li>
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</ol>
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</section>
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<section>
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<h2>What is Fomu?</h2>
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<ul>
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<li>ICE40UP5K</li>
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<li>2MB QSPI flash memory</li>
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<li>Four edge-plated pads</li>
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<li>ESD protection</li>
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<li>USB implemented in HDL</li>
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<li class="fragment highlight-blue">Fits in your USB port</li>
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</ul>
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<!-- <p>
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Fomu is an FPGA that fits in your USB port. It has foru buttons, 2 MB of SPI flash, an RGB LED, and an ICE40UP5K with 5280 LCs. It also has 128 kB of dedicated RAM, not counting the block RAM.
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Unlike many other PCBs, Fomu does not have a separate USB controller chip. This means that any projects that want to use the USB port must include a USB softcore.
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</p> -->
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</section>
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<section>
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<h2>Fomu Block Design Diagram</h2>
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<img data-src="img/fomu-block-diagram.png" alt="Fomu block diagram">
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</section>
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<section>
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<h2>What is this PCB?</h2>
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<img data-src="img/tomu-fpga-evt-1-small.jpg" alt="Fomu EVT1">
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<h3>Fomu EVT1</h3>
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<!-- <p>
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This is Fomu EVT1. This is the original stretch prototype of Fomu. The schematics are the same, but much has changed:
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* Name changed from Tomu-FPGA to Fomu
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* Package changed from SG48 to WLCSP32
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Additionally, some patches were needed to get this PCB working:
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* SO-8 for SPI flash was too small
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* Crystal footprint was upside-down
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These are yours to take home with you!
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Differences between EVT1 and EVT3:
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* Silkscreen on Raspberry Pi header
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* Populate Raspberry Pi header
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* Add PMOD pins to touchpads
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* Swap PMODa pins for I3C
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</p> -->
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</section>
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<section>
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<h2>Misleading Datasheets</h2>
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<img data-src="img/xtal-datasheet-icon.jpg" alt="Footprint from Crystal">
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</section>
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<section>
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<h2>What modifications does it have?</h2>
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<ul>
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<li>Shorting out two zero-ohm resistors (R7, PU)</li>
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<li>Programming SPI flash</li>
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<li>Bending SPI flash pins inward (U4)</li>
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<li>Mounting crystal on its side (U7)</li>
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<li>Attaching power to crystal</li>
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</ul>
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</section>
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<section>
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<h2>Fomu SPI Flash Layout</h2>
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<img data-src="img/fomu-memory-layout.png" alt="Fomu memory layout">
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<!-- <ol>
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<li>Bootloader</li>
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<li>Recovery</li>
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<li>Magic constants</li>
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<li>Interpreters</li>
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<li>Updates</li>
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</ol> -->
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</section>
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</section>
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<section>
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<section>
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<h2>Working with Fomu</h2>
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</section>
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<section>
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<h2>FAT Bootloader</h2>
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<ul>
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<li>Presents itself as a USB disk</li>
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<li>Drag and drop files to program</li>
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<li>Multiple interpreter support</li>
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</ul>
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<div>
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<img data-src="img/under-construction.gif" class="fragment">
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</div>
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</section>
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<section>
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<h2>"fail safe" bootloader</h2>
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Device Firmware Update - <strong>DFU</strong>
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</section>
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<section>
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<h2>Updating Fomu</h2>
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<pre><code>$ dfu-util -l
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Found DFU: [1209:5bf0] name="Fomu DFU Bootloader v1.7.2"
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$ dfu-util -D evt-installable.dfu
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Download [========= ] 36% 38912 bytes
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Download done.
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$ dfu-util -l
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Found DFU: [1209:5bf0] name="Fomu DFU Bootloader v1.8.1"
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$</code></pre>
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</section>
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</section>
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<section>
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<section>
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<h2>Python / Interpreted</h2>
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<ol>
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<li><strong>Goal:</strong> Multiple interpreters, auto-reload, USB disk interface</li>
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<li><strong>Now:</strong> MicroPython binary</li>
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</ol>
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</section>
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<section>
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<h2>Loading Programs onto Fomu</h2>
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<pre><code>
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$ dfu-util -l
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Found DFU: [1209:5bf0] name="Fomu DFU Bootloader v1.8.1"
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$ dfu-util -e # Boot current program
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$ dfu-util -D new-image.dfu # Load new program</code></pre>
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<h3 class="fragment">u<code>5b f0</code>mu</h3>
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</section>
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<section>
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<h2>Loading MicroPython</h2>
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<pre><code>$ dfu-util -D micropython-fomu.dfu</code></pre>
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</section>
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<section>
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<h2>Connecting via serial</h2>
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<pre class="fragment"><code>screen /dev/cu.usbserial*</code></pre>
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<pre class="fragment"><code>screen /dev/ttyACM*</code></pre>
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<pre class="fragment"><code>Tera Term</code></pre>
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<pre class="fragment"><code>MicroPython v1.10-296-g0a5a77a on 2019-06-18; fomu with vexriscv
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>>></code></pre>
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</section>
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<section>
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<h2>Interacting with Fomu</h2>
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<pre><code class="python" data-trim>
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>>> import fomu
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>>> rgb = fomu.rgb()
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>>> rgb.mode("error")
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>>>
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</code></pre>
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</section>
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<section>
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<h2>RGB LEDD reference</h2>
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<img data-src="img/ice40-ledd.png" alt="ICE40 LEDD registers">
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<pre class="fragment"><code class="python" data-trim>>>> rgb.write_raw(0b0001, 255)
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>>> rgb.write_raw(0b1010, 14)
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>>> rgb.write_raw(0b1011, 1)
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>>> </code></pre>
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</section>
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<section>
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<h2>Future Work</h2>
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<ul>
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<li>CircuitPython</li>
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<li>eLua</li>
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<li>Espurino?</li>
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</ul>
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</section>
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</section>
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<section>
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<section>
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<h2>RISC-V</h2>
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</section>
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<section>
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<h2>LiteX Model</h2>
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<img data-src="img/litex-design.png" alt="LiteX Design">
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</section>
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<section>
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<h2>Wishbone Bridge</h2>
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<img data-src="img/wishbone-usb-debug-bridge.png" alt="Wishbone bridge">
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</section>
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<section>
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<h2>CPU is Optional</h2>
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<ul>
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<li>Multiple CPUs available</li>
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<li>
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<ul>
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<li>VexRiscv</li>
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<li>picorv32</li>
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|
<li>lm32</li>
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<li>...</li>
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</ul>
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</li>
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<li>Also works just fine with no CPU</li>
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</ul>
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</section>
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<section>
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<h2>CSR Access</h2>
|
|
<pre><code class="cpp">#define CSR_VERSION_MAJOR_ADDR 0xe0007000
|
|
#define CSR_VERSION_MAJOR_SIZE 1
|
|
#define CSR_VERSION_MINOR_ADDR 0xe0007004
|
|
#define CSR_VERSION_MINOR_SIZE 1
|
|
#define CSR_VERSION_REVISION_ADDR 0xe0007008
|
|
#define CSR_VERSION_REVISION_SIZE 1
|
|
#define CSR_VERSION_GITREV_ADDR 0xe000700c
|
|
#define CSR_VERSION_GITREV_SIZE 4
|
|
#define CSR_VERSION_GITEXTRA_ADDR 0xe000701c
|
|
#define CSR_VERSION_GITEXTRA_SIZE 2
|
|
</code></pre>
|
|
Excerpt from <code>csr.h</code>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Reading CPU Version</h2>
|
|
<pre><code class="sh">$ wishbone-tool --pid 0x5bf0 0xe0007000
|
|
Value at e0007000: 00000001
|
|
$ wishbone-tool --pid 0x5bf0 0xe0007004
|
|
Value at e0007004: 00000008
|
|
$ wishbone-tool --pid 0x5bf0 0xe0007008
|
|
Value at e0007008: 00000001</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Interacting with LEDD directly</h2>
|
|
<img data-src="img/ice40-ledd.png" alt="ICE40 LEDD registers">
|
|
<pre class="fragment"><code class="cpp">#define CSR_RGB_DAT_ADDR 0xe0006800L
|
|
#define CSR_RGB_ADDR_ADDR 0xe0006804L</code></pre>
|
|
<pre class="fragment"><code>$ wishbone-tool --pid 0x5bf0 0xe0006804 1
|
|
$ wishbone-tool --pid 0x5bf0 0xe0006800 0xff</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Writing RISC-V Code</h2>
|
|
<pre><code>$ make
|
|
CC ./src/main.c main.o
|
|
CC ./src/rgb.c rgb.o
|
|
CC ./src/time.c time.o
|
|
AS ./src/crt0-vexriscv.S crt0-vexriscv.o
|
|
LD riscv-blink.elf
|
|
OBJCOPY riscv-blink.bin
|
|
IHEX riscv-blink.ihex
|
|
$ </code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Modifying RISC-V Code</h2>
|
|
<pre><code class="diff">--- a/riscv-blink/src/main.c
|
|
+++ b/riscv-blink/src/main.c
|
|
@@ -38,6 +38,7 @@ void isr(void) {
|
|
void main(void) {
|
|
rgb_init();
|
|
irq_setie(0);
|
|
+ rgb_write((100000/64000)-1, LEDDBR);
|
|
int i = 0;
|
|
while (1) {
|
|
i++;</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Other RISC-V Programs</h2>
|
|
riscv-usb-cdcacm: echo characters back after adding 1
|
|
</section>
|
|
</section>
|
|
|
|
<section>
|
|
<section>
|
|
<h2>Hardware Description Language</h2>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Yosys and NextPNR</h2>
|
|
<ul>
|
|
<li>Timing Driven!</li>
|
|
</ul>
|
|
<pre><code>Max frequency for clock 'clk12': 24.63 MHz (PASS at 12.00 MHz)
|
|
Max frequency for clock 'clk48_1': 60.66 MHz (PASS at 48.00 MHz)
|
|
Max frequency for clock 'clkraw': 228.05 MHz (PASS at 48.00 MHz)</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Blinking an LED</h2>
|
|
<pre><code>$ make FOMU_REV=evt
|
|
...
|
|
20 warnings, 0 errors
|
|
PACK blink.bin
|
|
Built 'blink' for Fomu evt1
|
|
$ dfu-util -D blink.bin</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>LiteX and MiGen</h2>
|
|
<ol>
|
|
<li>Define hardware in Python</li>
|
|
<li>Evaluate Python to produce netlist</li>
|
|
<li>Synthesize netlist to FPGA</li>
|
|
</ol>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>lxbuildenv.py</h2>
|
|
<ol>
|
|
<li>Python environment using native interpreter</li>
|
|
<li>Very stable, good for hardware projects</li>
|
|
<li>Should work with system Python</li>
|
|
<li>Runs on Linux, Windows, Raspberry Pi</li>
|
|
</ol>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Why do we need a CPU?</h2>
|
|
<img data-src="img/litex-design.png" alt="LiteX Design">
|
|
</section>
|
|
|
|
<section>
|
|
<h2>What if we remove the CPU?</h2>
|
|
<ul>
|
|
<li>Workshop project has no CPU</li>
|
|
<li>DummyUsb module automatically enumerates</li>
|
|
<li>Wishbone Debug Bridge still accessible</li>
|
|
</ul>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Build Workshop Module</h2>
|
|
<pre><code>$ python3 workshop.py --placer heap
|
|
...
|
|
5 warnings, 0 errors
|
|
$ </code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Load onto Fomu</h2>
|
|
<pre><code>$ dfu-util -D build/gateware/top.bin
|
|
Download [=========================] 100% 104090 bytes
|
|
Download done.
|
|
$ </code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Write a value to RAM</h2>
|
|
<pre><code>$ wishbone-tool --pid 0x5bf0 0x10000000
|
|
Value at 10000000: 0baf801e
|
|
$ wishbone-tool --pid 0x5bf0 0x10000000 0x12345678
|
|
$ wishbone-tool --pid 0x5bf0 0x10000000
|
|
Value at 10000000: 12345678
|
|
$ </code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Adding Hardware</h2>
|
|
<img data-src="img/ice40-rgb.jpg" alt="Schematic of RGB block">
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Technology Library Reference</h2>
|
|
<pre><code class="verilog">// Verilog Instantiation
|
|
SB_RGBA_DRV RGBA_DRIVER (
|
|
.CURREN(ENABLE_CURR),
|
|
.RGBLEDEN(ENABLE_RGBDRV),
|
|
.RGB0PWM(RGB0),
|
|
.RGB1PWM(RGB1),
|
|
.RGB2PWM(RGB2),
|
|
.RGB0(LED0),
|
|
.RGB1(LED1),
|
|
.RGB2(LED2)
|
|
);
|
|
defparam RGBA_DRIVER.CURRENT_MODE = "0b0";
|
|
defparam RGBA_DRIVER.RGB0_CURRENT = "0b111111";
|
|
defparam RGBA_DRIVER.RGB1_CURRENT = "0b111111" ;
|
|
defparam RGBA_DRIVER.RGB2_CURRENT = "0b111111";</code></pre>
|
|
<p>SBTICETechnologyLibrary201504.pdf page 147</p>
|
|
</section>
|
|
<section>
|
|
<h2>RGB Block</h2>
|
|
<pre><code class="python" style="font-size: 18px; line-height: 22px">class FomuRGB(Module, AutoCSR):
|
|
def __init__(self, pads):
|
|
self.output = CSRStorage(3)
|
|
self.specials += Instance("SB_RGBA_DRV",
|
|
i_CURREN = 0b1,
|
|
i_RGBLEDEN = 0b1,
|
|
i_RGB0PWM = self.output.storage[0],
|
|
i_RGB1PWM = self.output.storage[1],
|
|
i_RGB2PWM = self.output.storage[2],
|
|
o_RGB0 = pads.r,
|
|
o_RGB1 = pads.g,
|
|
o_RGB2 = pads.b,
|
|
p_CURRENT_MODE = "0b1",
|
|
p_RGB0_CURRENT = "0b000011",
|
|
p_RGB1_CURRENT = "0b000011",
|
|
p_RGB2_CURRENT = "0b000011",
|
|
)</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Instantiating FomuRGB</h2>
|
|
<pre><code class="diff">@@ -55,6 +75,10 @@ class BaseSoC(SoCCore):
|
|
with_ctrl=False,
|
|
**kwargs)
|
|
|
|
+ # Add the LED driver block
|
|
+ led_pads = platform.request("rgb_led")
|
|
+ self.submodules.rgb = FomuRGB(led_pads)
|
|
+
|
|
# UP5K has single port RAM....
|
|
# Use this as CPU RAM.
|
|
spram_size = 128*1024</code></pre>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>Interacting with the CSR</h2>
|
|
<pre><code>csr_register,rgb_output,0xe0006800,1,rw</code></pre>
|
|
<p>From <code>test/csr.csv</code></p>
|
|
</section>
|
|
|
|
<section>
|
|
<h2>VexRiscv</h2>
|
|
</section>
|
|
</section>
|
|
</div>
|
|
</div> <!-- class="reveal" -->
|
|
<!-- End of main presentation -->
|
|
|
|
<!-- Start of configuration section -->
|
|
<script src="lib/js/head.min.js"></script>
|
|
<script src="js/reveal.js"></script>
|
|
|
|
<script>
|
|
var presenter = !!Reveal.getQueryHash().s;
|
|
|
|
// More info https://github.com/hakimel/reveal.js#configuration
|
|
Reveal.initialize({
|
|
controls: presenter ? false : true,
|
|
progress: true,
|
|
history: true,
|
|
center: true,
|
|
controlsTutorial: presenter ? false : true,
|
|
|
|
slideNumber: presenter ? null : 'c/t',
|
|
|
|
// The "normal" size of the presentation, aspect ratio will be preserved
|
|
// when the presentation is scaled to fit different resolutions. Can be
|
|
// specified using percentage units.
|
|
width: 960,
|
|
height: 700,
|
|
|
|
// Factor of the display size that should remain empty around the content
|
|
margin: 0.1,
|
|
|
|
multiplex: {
|
|
url: 'https://p.xobs.io/',
|
|
id: 'cbd6556886c2825d',
|
|
secret: Reveal.getQueryHash().s || null
|
|
},
|
|
|
|
// Bounds for smallest/largest possible scale to apply to content
|
|
minScale: 0.02,
|
|
maxScale: 5.5,
|
|
|
|
transition: 'slide', // none/fade/slide/convex/concave/zoom
|
|
|
|
// More info https://github.com/hakimel/reveal.js#dependencies
|
|
dependencies: [
|
|
{ src: 'lib/js/classList.js', condition: function () { return !document.body.classList; } },
|
|
{ src: 'plugin/markdown/marked.js', condition: function () { return !!document.querySelector('[data-markdown]'); } },
|
|
{ src: 'plugin/markdown/markdown.js', condition: function () { return !!document.querySelector('[data-markdown]'); } },
|
|
{ src: 'plugin/highlight/highlight.js', async: true, callback: function () { hljs.initHighlightingOnLoad(); } },
|
|
{ src: 'plugin/search/search.js', async: true },
|
|
{ src: 'plugin/zoom-js/zoom.js', async: true },
|
|
{ src: 'plugin/notes/notes.js', async: true },
|
|
|
|
{ src: 'lib/js/socket.io.js', async: true },
|
|
{
|
|
src: presenter ?
|
|
'plugin/multiplex/master.js' :
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'plugin/multiplex/client.js', async: true
|
|
},
|
|
]
|
|
});
|
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</script>
|
|
</body>
|
|
|
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</html> |