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| <li class="toctree-l3 current"><a class="current reference internal" href="#">Espressif ESP32</a><ul> |
| <li class="toctree-l4"><a class="reference internal" href="#toolchain">Toolchain</a><ul> |
| <li class="toctree-l5"><a class="reference internal" href="#building-from-source">Building from source</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l4"><a class="reference internal" href="#flashing">Flashing</a><ul> |
| <li class="toctree-l5"><a class="reference internal" href="#bootloader-and-partitions">Bootloader and partitions</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l4"><a class="reference internal" href="#peripheral-support">Peripheral Support</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="#memory-map">Memory Map</a><ul> |
| <li class="toctree-l5"><a class="reference internal" href="#address-mapping">Address Mapping</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="#embedded-memory">Embedded Memory</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="#boundary-address">Boundary Address</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="#external-memory">External Memory</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="#id1">Boundary Address</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="#linker-segments">Linker Segments</a></li> |
| </ul> |
| </li> |
| <li class="toctree-l4"><a class="reference internal" href="#bit-timers">64-bit Timers</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="#watchdog-timers">Watchdog Timers</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="#smp">SMP</a><ul> |
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| <li class="toctree-l4"><a class="reference internal" href="#using-qemu">Using QEMU</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="#things-to-do">Things to Do</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="#supported-boards">Supported Boards</a><ul> |
| <li class="toctree-l5"><a class="reference internal" href="boards/esp32-devkitc/index.html">ESP32 DevKitC</a></li> |
| <li class="toctree-l5"><a class="reference internal" href="boards/esp32-wrover-kit/index.html">ESP-WROVER-KIT</a></li> |
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| |
| <section id="espressif-esp32"> |
| <h1>Espressif ESP32<a class="headerlink" href="#espressif-esp32" title="Permalink to this heading"></a></h1> |
| <p>The ESP32 is a series of single and dual-core SoCs from Espressif |
| based on Harvard architecture Xtensa LX6 CPUs and with on-chip support |
| for Bluetooth and WiFi.</p> |
| <p>All embedded memory, external memory and peripherals are located on the |
| data bus and/or the instruction bus of these CPUs. With some minor |
| exceptions, the address mapping of two CPUs is symmetric, meaning they |
| use the same addresses to access the same memory. Multiple peripherals in |
| the system can access embedded memory via DMA.</p> |
| <p>On dual-core SoCs, the two CPUs are typically named “PRO_CPU” and “APP_CPU” |
| (for “protocol” and “application”), however for most purposes the |
| two CPUs are interchangeable.</p> |
| <section id="toolchain"> |
| <h2>Toolchain<a class="headerlink" href="#toolchain" title="Permalink to this heading"></a></h2> |
| <p>You can use the prebuilt <a class="reference external" href="https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/tools/idf-tools.html#xtensa-esp32-elf">toolchain</a> |
| for Xtensa architecture and <a class="reference external" href="https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/tools/idf-tools.html#openocd-esp32">OpenOCD</a> |
| for ESP32 by Espressif.</p> |
| <p>For flashing firmware, you will need to install <code class="docutils literal notranslate"><span class="pre">esptool.py</span></code> by running:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>$ pip install esptool |
| </pre></div> |
| </div> |
| <section id="building-from-source"> |
| <h3>Building from source<a class="headerlink" href="#building-from-source" title="Permalink to this heading"></a></h3> |
| <p>You can also build the toolchain yourself. The steps to |
| build the toolchain with crosstool-NG on Linux are as follows</p> |
| <div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>git<span class="w"> </span>clone<span class="w"> </span>https://github.com/espressif/crosstool-NG.git |
| <span class="gp">$ </span><span class="nb">cd</span><span class="w"> </span>crosstool-NG |
| <span class="gp">$ </span>git<span class="w"> </span>checkout<span class="w"> </span>esp-2021r1 |
| <span class="gp">$ </span>git<span class="w"> </span>submodule<span class="w"> </span>update<span class="w"> </span>--init |
| |
| <span class="gp">$ </span>./bootstrap<span class="w"> </span><span class="o">&&</span><span class="w"> </span>./configure<span class="w"> </span>--enable-local<span class="w"> </span><span class="o">&&</span><span class="w"> </span>make |
| |
| <span class="gp">$ </span>./ct-ng<span class="w"> </span>xtensa-esp32-elf |
| <span class="gp">$ </span>./ct-ng<span class="w"> </span>build |
| |
| <span class="gp">$ </span>chmod<span class="w"> </span>-R<span class="w"> </span>u+w<span class="w"> </span>builds/xtensa-esp32-elf |
| |
| <span class="gp">$ </span><span class="nb">export</span><span class="w"> </span><span class="nv">PATH</span><span class="o">=</span><span class="s2">"crosstool-NG/builds/xtensa-esp32-elf/bin:</span><span class="nv">$PATH</span><span class="s2">"</span> |
| </pre></div> |
| </div> |
| <p>These steps are given in the setup guide in |
| <a class="reference external" href="https://docs.espressif.com/projects/esp-idf/en/latest/get-started/linux-setup-scratch.html">ESP-IDF documentation</a>.</p> |
| </section> |
| </section> |
| <section id="flashing"> |
| <h2>Flashing<a class="headerlink" href="#flashing" title="Permalink to this heading"></a></h2> |
| <p>Firmware for ESP32 is flashed via the USB/UART interface using the <code class="docutils literal notranslate"><span class="pre">esptool.py</span></code> tool. |
| It’s a two step process where the first converts the ELF file into a ESP32-compatible binary |
| and the second flashes it to the board. These steps are included into the build system and you can |
| flash your NuttX firmware simply by running:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>$ make download ESPTOOL_PORT=<port> |
| </pre></div> |
| </div> |
| <p>where <code class="docutils literal notranslate"><span class="pre"><port></span></code> is typically <code class="docutils literal notranslate"><span class="pre">/dev/ttyUSB0</span></code> or similar. You can change the baudrate by passing <code class="docutils literal notranslate"><span class="pre">ESPTOOL_BAUD</span></code>.</p> |
| <section id="bootloader-and-partitions"> |
| <h3>Bootloader and partitions<a class="headerlink" href="#bootloader-and-partitions" title="Permalink to this heading"></a></h3> |
| <p>ESP32 requires a bootloader to be flashed as well as a set of FLASH partitions. This is only needed the first time |
| (or any time you which to modify either of these). An easy way is to use prebuilt binaries for NuttX from <a class="reference external" href="https://github.com/espressif/esp-nuttx-bootloader">here</a>. In there you will find instructions to rebuild these if necessary. |
| Once you downloaded both binaries, you can flash them by adding an <code class="docutils literal notranslate"><span class="pre">ESPTOOL_BINDIR</span></code> parameter, pointing to the directory where these binaries were downloaded:</p> |
| <div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>make<span class="w"> </span>download<span class="w"> </span><span class="nv">ESPTOOL_PORT</span><span class="o">=</span><port><span class="w"> </span><span class="nv">ESPTOOL_BINDIR</span><span class="o">=</span><dir> |
| </pre></div> |
| </div> |
| <div class="admonition note"> |
| <p class="admonition-title">Note</p> |
| <p>It is recommended that if this is the first time you are using the board with NuttX that you perform a complete |
| SPI FLASH erase.</p> |
| <div class="highlight-console notranslate"><div class="highlight"><pre><span></span><span class="gp">$ </span>esptool.py<span class="w"> </span>erase_flash |
| </pre></div> |
| </div> |
| </div> |
| </section> |
| </section> |
| <section id="peripheral-support"> |
| <h2>Peripheral Support<a class="headerlink" href="#peripheral-support" title="Permalink to this heading"></a></h2> |
| <p>The following list indicates the state of peripherals’ support in NuttX:</p> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>Peripheral</p></th> |
| <th class="head"><p>Support</p></th> |
| <th class="head"><p>NOTES</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p>GPIO</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>UART</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>SPI</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>I2C</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>DMA</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Wifi</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Ethernet</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>SPIFLASH</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>SPIRAM</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Timers</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Watchdog</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>RTC</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>RNG</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>AES</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>eFuse</p></td> |
| <td><p>Yes</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>ADC</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Bluetooth</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>SDIO</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>SD/MMC</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>I2S</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>LED_PWM</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>RMT</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>MCPWM</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Pulse_CNT</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>SHA</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>RSA</p></td> |
| <td><p>No</p></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| </section> |
| <section id="memory-map"> |
| <h2>Memory Map<a class="headerlink" href="#memory-map" title="Permalink to this heading"></a></h2> |
| <section id="address-mapping"> |
| <h3>Address Mapping<a class="headerlink" href="#address-mapping" title="Permalink to this heading"></a></h3> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>BUS TYPE</p></th> |
| <th class="head"><p>START</p></th> |
| <th class="head"><p>LAST</p></th> |
| <th class="head"><p>DESCRIPTION</p></th> |
| <th class="head"><p>NOTES</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3F400000</p></td> |
| <td><p>0x3F7FFFFF</p></td> |
| <td><p>External Memory</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data</p></td> |
| <td><p>0x3F800000 |
| 0x3FC00000</p></td> |
| <td><p>0x3FBFFFFF |
| 0x3FEFFFFF</p></td> |
| <td><p>External Memory</p></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3FF00000</p></td> |
| <td><p>0x3FF7FFFF</p></td> |
| <td><p>Peripheral</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data</p></td> |
| <td><p>0x3FF80000</p></td> |
| <td><p>0x3FFFFFFF</p></td> |
| <td><p>Embedded Memory</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Instruction</p></td> |
| <td><p>0x40000000</p></td> |
| <td><p>0x400C1FFF</p></td> |
| <td><p>Embedded Memory</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Instruction</p></td> |
| <td><p>0x400C2000</p></td> |
| <td><p>0x40BFFFFF</p></td> |
| <td><p>External Memory</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>.</p></td> |
| <td><p>0x40C00000</p></td> |
| <td><p>0x4FFFFFFF</p></td> |
| <td></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data / Instruction</p></td> |
| <td><p>0x50000000</p></td> |
| <td><p>0x50001FFF</p></td> |
| <td><p>Embedded Memory</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>.</p></td> |
| <td><p>0x50002000</p></td> |
| <td><p>0xFFFFFFFF</p></td> |
| <td></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| </tbody> |
| </table> |
| </section> |
| <section id="embedded-memory"> |
| <h3>Embedded Memory<a class="headerlink" href="#embedded-memory" title="Permalink to this heading"></a></h3> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>BUS TYPE</p></th> |
| <th class="head"><p>START</p></th> |
| <th class="head"><p>LAST</p></th> |
| <th class="head"><p>DESCRIPTION</p></th> |
| <th class="head"><p>NOTES</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3ff80000</p></td> |
| <td><p>0x3ff81fff</p></td> |
| <td><p>RTC FAST Memory</p></td> |
| <td><p>PRO_CPU Only</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>.</p></td> |
| <td><p>0x3ff82000</p></td> |
| <td><p>0x3ff8ffff</p></td> |
| <td></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3ff90000</p></td> |
| <td><p>0x3ff9ffff</p></td> |
| <td><p>Internal ROM 1</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>.</p></td> |
| <td><p>0x3ffa0000</p></td> |
| <td><p>0x3ffadfff</p></td> |
| <td></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3ffae000</p></td> |
| <td><p>0x3ffdffff</p></td> |
| <td><p>Internal SRAM 2</p></td> |
| <td><p>DMA</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data</p></td> |
| <td><p>0x3ffe0000</p></td> |
| <td><p>0x3fffffff</p></td> |
| <td><p>Internal SRAM 1</p></td> |
| <td><p>DMA</p></td> |
| </tr> |
| </tbody> |
| </table> |
| </section> |
| <section id="boundary-address"> |
| <h3>Boundary Address<a class="headerlink" href="#boundary-address" title="Permalink to this heading"></a></h3> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>BUS TYPE</p></th> |
| <th class="head"><p>START</p></th> |
| <th class="head"><p>LAST</p></th> |
| <th class="head"><p>DESCRIPTION</p></th> |
| <th class="head"><p>NOTES</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p>Instruction</p></td> |
| <td><p>0x40000000</p></td> |
| <td><p>0x40007fff</p></td> |
| <td><p>Internal ROM 0</p></td> |
| <td><p>Remap</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Instruction</p></td> |
| <td><p>0x40008000</p></td> |
| <td><p>0x4005ffff</p></td> |
| <td><p>Internal ROM 0</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>.</p></td> |
| <td><p>0x40060000</p></td> |
| <td><p>0x4006ffff</p></td> |
| <td></td> |
| <td><p>Reserved</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Instruction</p></td> |
| <td><p>0x40070000</p></td> |
| <td><p>0x4007ffff</p></td> |
| <td><p>Internal SRAM 0</p></td> |
| <td><p>Cache</p></td> |
| </tr> |
| <tr class="row-even"><td><p>Instruction</p></td> |
| <td><p>0x40080000</p></td> |
| <td><p>0x4009ffff</p></td> |
| <td><p>Internal SRAM 0</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-odd"><td><p>Instruction</p></td> |
| <td><p>0x400a0000</p></td> |
| <td><p>0x400affff</p></td> |
| <td><p>Internal SRAM 1</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Instruction</p></td> |
| <td><p>0x400b0000</p></td> |
| <td><p>0x400b7FFF</p></td> |
| <td><p>Internal SRAM 1</p></td> |
| <td><p>Remap</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Instruction</p></td> |
| <td><p>0x400b8000</p></td> |
| <td><p>0x400bffff</p></td> |
| <td><p>Internal SRAM 1</p></td> |
| <td></td> |
| </tr> |
| <tr class="row-even"><td><p>Instruction</p></td> |
| <td><p>0x400c0000</p></td> |
| <td><p>0x400c1FFF</p></td> |
| <td><p>RTC FAST Memory</p></td> |
| <td><p>PRO_CPU Only</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data / Instruction</p></td> |
| <td><p>0x50000000</p></td> |
| <td><p>0x50001fff</p></td> |
| <td><p>RTC SLOW Memory</p></td> |
| <td></td> |
| </tr> |
| </tbody> |
| </table> |
| </section> |
| <section id="external-memory"> |
| <h3>External Memory<a class="headerlink" href="#external-memory" title="Permalink to this heading"></a></h3> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>BUS TYPE</p></th> |
| <th class="head"><p>START</p></th> |
| <th class="head"><p>LAST</p></th> |
| <th class="head"><p>DESCRIPTION</p></th> |
| <th class="head"><p>NOTES</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p>Data</p></td> |
| <td><p>0x3f400000</p></td> |
| <td><p>0x3f7fffff</p></td> |
| <td><p>External Flash</p></td> |
| <td><p>Read</p></td> |
| </tr> |
| <tr class="row-odd"><td><p>Data</p></td> |
| <td><p>0x3f800000</p></td> |
| <td><p>0x3fbfffff</p></td> |
| <td><p>External SRAM</p></td> |
| <td><p>Read and Write</p></td> |
| </tr> |
| </tbody> |
| </table> |
| </section> |
| <section id="id1"> |
| <h3>Boundary Address<a class="headerlink" href="#id1" title="Permalink to this heading"></a></h3> |
| <p>Instruction 0x400c2000 0x40bfffff 11512 KB External Flash Read</p> |
| </section> |
| <section id="linker-segments"> |
| <h3>Linker Segments<a class="headerlink" href="#linker-segments" title="Permalink to this heading"></a></h3> |
| <table class="docutils align-default"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>DESCRIPTION</p></th> |
| <th class="head"><p>START</p></th> |
| <th class="head"><p>END</p></th> |
| <th class="head"><p>ATTR</p></th> |
| <th class="head"><p>LINKER SEGMENT NAME</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><dl class="simple"> |
| <dt>FLASH mapped data:</dt><dd><ul class="simple"> |
| <li><p>.rodata</p></li> |
| <li><p>Constructors |
| /destructors</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x3f400010</p></td> |
| <td><p>0x3fc00010</p></td> |
| <td><p>R</p></td> |
| <td><p>drom0_0_seg</p></td> |
| </tr> |
| <tr class="row-odd"><td><dl class="simple"> |
| <dt>COMMON data RAM:</dt><dd><ul class="simple"> |
| <li><p>.bss/.data</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x3ffb0000</p></td> |
| <td><p>0x40000000</p></td> |
| <td><p>RW</p></td> |
| <td><p>dram0_0_seg (NOTE 1,2,3)</p></td> |
| </tr> |
| <tr class="row-even"><td><dl class="simple"> |
| <dt>IRAM for PRO cpu:</dt><dd><ul class="simple"> |
| <li><p>Interrupt Vectors</p></li> |
| <li><p>Low level |
| handlers</p></li> |
| <li><p>Xtensa/Espressif |
| libraries</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x40080000</p></td> |
| <td><p>0x400a0000</p></td> |
| <td><p>RX</p></td> |
| <td><p>iram0_0_seg</p></td> |
| </tr> |
| <tr class="row-odd"><td><dl class="simple"> |
| <dt>RTC fast memory:</dt><dd><ul class="simple"> |
| <li><p>.rtc.text |
| (unused?)</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x400c0000</p></td> |
| <td><p>0x400c2000</p></td> |
| <td><p>RWX</p></td> |
| <td><p>rtc_iram_seg (PRO_CPU only)</p></td> |
| </tr> |
| <tr class="row-even"><td><dl class="simple"> |
| <dt>FLASH:</dt><dd><ul class="simple"> |
| <li><p>.text</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x400d0018</p></td> |
| <td><p>0x40400018</p></td> |
| <td><p>RX</p></td> |
| <td><p>iram0_2_seg (actually FLASH)</p></td> |
| </tr> |
| <tr class="row-odd"><td><dl class="simple"> |
| <dt>RTC slow memory:</dt><dd><ul class="simple"> |
| <li><p>.rtc.data/rodata |
| (unused?)</p></li> |
| </ul> |
| </dd> |
| </dl> |
| </td> |
| <td><p>0x50000000</p></td> |
| <td><p>0x50001000</p></td> |
| <td><p>RW</p></td> |
| <td><p>rtc_slow_seg (NOTE 4)</p></td> |
| </tr> |
| </tbody> |
| </table> |
| <div class="admonition note"> |
| <p class="admonition-title">Note</p> |
| <ol class="arabic simple"> |
| <li><p>Linker script will reserve space at the beginning of the segment |
| for BT and at the end for trace memory.</p></li> |
| <li><p>Heap ends at the top of dram_0_seg.</p></li> |
| <li><p>Parts of this region is reserved for the ROM bootloader.</p></li> |
| <li><p>Linker script will reserve space at the beginning of the segment |
| for co-processor reserve memory and at the end for ULP coprocessor |
| reserve memory.</p></li> |
| </ol> |
| </div> |
| </section> |
| </section> |
| <section id="bit-timers"> |
| <h2>64-bit Timers<a class="headerlink" href="#bit-timers" title="Permalink to this heading"></a></h2> |
| <p>ESP32 has 4 generic timers of 64 bits (2 from Group 0 and 2 from Group 1). They’re |
| accessible as character drivers, the configuration along with a guidance on how |
| to run the example and the description of the application level interface |
| can be found <a class="reference internal" href="../../../components/drivers/character/timer.html"><span class="doc">here</span></a>.</p> |
| </section> |
| <section id="watchdog-timers"> |
| <h2>Watchdog Timers<a class="headerlink" href="#watchdog-timers" title="Permalink to this heading"></a></h2> |
| <p>ESP32 has 3 WDTs. 2 MWDTS from the Timers Module and 1 RWDT from the RTC Module |
| (Currently not supported yet). They’re accessible as character drivers, |
| The configuration along with a guidance on how to run the example and the description |
| of the application level interface can be found |
| <a class="reference internal" href="../../../components/drivers/character/watchdog.html"><span class="doc">here</span></a>.</p> |
| </section> |
| <section id="smp"> |
| <h2>SMP<a class="headerlink" href="#smp" title="Permalink to this heading"></a></h2> |
| <p>The ESP32 has 2 CPUs. Support is included for testing an SMP configuration. |
| That configuration is still not yet ready for usage but can be enabled with |
| the following configuration settings, |
| in <span class="menuselection">RTOS Features ‣ Tasks and Scheduling</span>, with:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>CONFIG_SPINLOCK=y |
| CONFIG_SMP=y |
| CONFIG_SMP_NCPUS=2 |
| </pre></div> |
| </div> |
| <p>Debug Tip: During debug session, OpenOCD may mysteriously switch from one |
| CPU to another. This behavior can be eliminated by uncommenting one of the |
| following in <code class="docutils literal notranslate"><span class="pre">scripts/esp32.cfg</span></code>:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span># Only configure the PRO CPU |
| #set ESP32_ONLYCPU 1 |
| # Only configure the APP CPU |
| #set ESP32_ONLYCPU 2 |
| </pre></div> |
| </div> |
| <section id="open-issues"> |
| <h3>Open Issues<a class="headerlink" href="#open-issues" title="Permalink to this heading"></a></h3> |
| <blockquote> |
| <div><ol class="arabic simple"> |
| <li><p>Cache Issues. I have not thought about this yet, but certainly caching is |
| an issue in an SMP system:</p> |
| <ul class="simple"> |
| <li><p>Cache coherency. Are there separate caches for each CPU? Or a single |
| shared cache? If the are separate then keep the caches coherent will |
| be an issue.</p></li> |
| <li><p>Caching MAY interfere with spinlocks as they are currently implemented. |
| Waiting on a cached copy of the spinlock may result in a hang or a |
| failure to wait.</p></li> |
| </ul> |
| </li> |
| <li><p>Assertions. On a fatal assertions, other CPUs need to be stopped.</p></li> |
| </ol> |
| </div></blockquote> |
| </section> |
| </section> |
| <section id="wifi"> |
| <h2>WiFi<a class="headerlink" href="#wifi" title="Permalink to this heading"></a></h2> |
| <p>A standard network interface will be configured and can be initialized such as:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>nsh> ifup wlan0 |
| nsh> wapi psk wlan0 mypasswd 3 |
| nsh> wapi essid wlan0 myssid 1 |
| nsh> renew wlan0 |
| </pre></div> |
| </div> |
| <p>In this case a connection to AP with SSID <code class="docutils literal notranslate"><span class="pre">myssid</span></code> is done, using <code class="docutils literal notranslate"><span class="pre">mypasswd</span></code> as |
| password. IP address is obtained via DHCP using <code class="docutils literal notranslate"><span class="pre">renew</span></code> command. You can check |
| the result by running <code class="docutils literal notranslate"><span class="pre">ifconfig</span></code> afterwards.</p> |
| <div class="admonition tip"> |
| <p class="admonition-title">Tip</p> |
| <p>Boards usually expose a <code class="docutils literal notranslate"><span class="pre">wapi</span></code> defconfig which enables WiFi</p> |
| </div> |
| </section> |
| <section id="wifi-softap"> |
| <h2>WiFi SoftAP<a class="headerlink" href="#wifi-softap" title="Permalink to this heading"></a></h2> |
| <p>It is possible to use ESP32 as an Access Point (SoftAP). Actually there are some |
| boards with a <code class="docutils literal notranslate"><span class="pre">sta_softap</span></code> which enables this support.</p> |
| <p>If you are using this board config profile you can run these commands to be able |
| to connect your smartphone or laptop to your board:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>nsh> ifup wlan1 |
| nsh> dhcpd_start wlan1 |
| nsh> wapi psk wlan0 mypasswd 1 |
| nsh> wapi essid wlan1 nuttxap 1 |
| </pre></div> |
| </div> |
| <p>In this case, you are creating the access point <code class="docutils literal notranslate"><span class="pre">nuttxapp</span></code> in your board and to |
| connect to it on your smartphone you will be required to type the password <code class="docutils literal notranslate"><span class="pre">mypasswd</span></code>. |
| The <code class="docutils literal notranslate"><span class="pre">dhcpd_start</span></code> is necessary to let your board to associate an IP to your smartphone.</p> |
| </section> |
| <section id="bluetooth"> |
| <h2>Bluetooth<a class="headerlink" href="#bluetooth" title="Permalink to this heading"></a></h2> |
| <p>Bluetooth is not currently supported.</p> |
| </section> |
| <section id="using-qemu"> |
| <h2>Using QEMU<a class="headerlink" href="#using-qemu" title="Permalink to this heading"></a></h2> |
| <p>First follow the instructions <a class="reference external" href="https://github.com/espressif/qemu/wiki">here</a> to build QEMU. |
| Enable the ESP32_QEMU_IMAGE config found in “Board Selection -> ESP32 binary image for QEMU”. |
| Download the bootloader and the partition table from <a class="reference external" href="https://github.com/espressif/esp-nuttx-bootloader/releases">https://github.com/espressif/esp-nuttx-bootloader/releases</a> |
| and place them in a directory, say ../esp-bins. |
| Build and generate the QEMU image: <cite>make ESPTOOL_BINDIR=../esp-bins</cite> |
| A new image “esp32_qemu_image.bin” will be created. It can be run as:</p> |
| <div class="highlight-none notranslate"><div class="highlight"><pre><span></span>~/PATH_TO_QEMU/qemu/build/xtensa-softmmu/qemu-system-xtensa -nographic \ |
| -machine esp32 \ |
| -drive file=esp32_qemu_image.bin,if=mtd,format=raw |
| </pre></div> |
| </div> |
| </section> |
| <section id="things-to-do"> |
| <h2>Things to Do<a class="headerlink" href="#things-to-do" title="Permalink to this heading"></a></h2> |
| <ol class="arabic"> |
| <li><p>Lazy co-processor save logic supported by Xtensa. That logic works like this:</p> |
| <ol class="loweralpha simple"> |
| <li><p>CPENABLE is set to zero on each context switch, disabling all co- |
| processors.</p></li> |
| <li><p>If/when the task attempts to use the disabled co-processor, an |
| exception occurs</p></li> |
| <li><p>The co-processor exception handler re-enables the co-processor.</p></li> |
| </ol> |
| <p>Instead, the NuttX logic saves and restores CPENABLE on each context |
| switch. This has disadvantages in that (1) co-processor context will |
| be saved and restored even if the co-processor was never used, and (2) |
| tasks must explicitly enable and disable co-processors.</p> |
| </li> |
| <li><p>Currently the Xtensa port copies register state save information from |
| the stack into the TCB. A more efficient alternative would be to just |
| save a pointer to a register state save area in the TCB. This would |
| add some complexity to signal handling and also to up_initialstate(). |
| But the performance improvement might be worth the effort.</p></li> |
| <li><p>See SMP-related issues above</p></li> |
| </ol> |
| </section> |
| <section id="supported-boards"> |
| <h2>Supported Boards<a class="headerlink" href="#supported-boards" title="Permalink to this heading"></a></h2> |
| <div class="toctree-wrapper compound"> |
| <ul> |
| <li class="toctree-l1"><a class="reference internal" href="boards/esp32-devkitc/index.html">ESP32 DevKitC</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="boards/esp32-wrover-kit/index.html">ESP-WROVER-KIT</a></li> |
| </ul> |
| </div> |
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