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| <section id="led-support"> |
| <h1>LED Support<a class="headerlink" href="#led-support" title="Permalink to this heading"></a></h1> |
| <p>A board architecture may or may not have LEDs. If the board does |
| have LEDs, then most architectures provide similar LED support |
| that is enabled when <code class="docutils literal notranslate"><span class="pre">CONFIG_ARCH_LEDS</span></code> is selected in the NuttX |
| configuration file. This LED support is part of |
| architecture-specific logic and is not managed by the core NuttX |
| logic. However, the support provided by each architecture is |
| sufficiently similar that it can be documented here.</p> |
| <section id="header-files"> |
| <h2>Header Files<a class="headerlink" href="#header-files" title="Permalink to this heading"></a></h2> |
| <p>LED-related definitions are provided in two header files:</p> |
| <ul class="simple"> |
| <li><p>LED definitions are provided for each board in the <code class="docutils literal notranslate"><span class="pre">board.h</span></code> |
| that resides in the <code class="docutils literal notranslate"><span class="pre"><board-name>/include/board.h</span></code> file |
| (which is also linked to <code class="docutils literal notranslate"><span class="pre">include/arch/board/board.h</span></code> when |
| the RTOS is configured). Those definitions are discussed |
| <a class="reference external" href="#leddefinitions">below</a>.</p></li> |
| <li><p>The board-specific logic provides unique instances of the LED |
| interfaces. This is because the implementation of LED support |
| may be very different on different boards. Prototypes for these |
| board-specific implementations are, however, provided in |
| architecture-common header files. That header file is usually |
| at <code class="docutils literal notranslate"><span class="pre"><arch-name>/src/common/up_internal.h</span></code>, but could be at |
| other locations in particular architectures. These prototypes |
| are discussed <a class="reference external" href="#ledapis">below</a>.</p></li> |
| </ul> |
| </section> |
| <section id="led-definitions"> |
| <h2>LED Definitions<a class="headerlink" href="#led-definitions" title="Permalink to this heading"></a></h2> |
| <p>The implementation of LED support is very specific to a board |
| architecture. Some boards have several LEDS, others have only one |
| or two. Some have none. Others LED matrices and show alphanumeric |
| data, etc. The NuttX logic does not refer to specific LEDS, |
| rather, it refers to an event to be shown on the LEDS in whatever |
| manner is appropriate for the board; the way that this event is |
| presented depends upon the hardware available on the board.</p> |
| <p>The model used by NuttX is that the board can show 8 events |
| defined as follows in <code class="docutils literal notranslate"><span class="pre"><board-name>/include/board.h</span></code>:</p> |
| <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#define LED_STARTED ??</span> |
| <span class="cp">#define LED_HEAPALLOCATE ??</span> |
| <span class="cp">#define LED_IRQSENABLED ??</span> |
| <span class="cp">#define LED_STACKCREATED ??</span> |
| <span class="cp">#define LED_INIRQ ??</span> |
| <span class="cp">#define LED_SIGNAL ??</span> |
| <span class="cp">#define LED_ASSERTION ??</span> |
| <span class="cp">#define LED_PANIC ??</span> |
| </pre></div> |
| </div> |
| <p>The specific value assigned to each pre-processor variable can be |
| whatever makes the implementation easiest for the board logic. The |
| <em>meaning</em> associated with each definition is as follows:</p> |
| <ul class="simple"> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_STARTED</span></code> is the value that describes the setting of the |
| LEDs when the LED logic is first initialized. This LED value is |
| set but never cleared.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_HEAPALLOCATE</span></code> indicates that the NuttX heap has been |
| configured. This is an important place in the boot sequence |
| because if the memory is configured wrong, it will probably |
| crash leaving this LED setting. This LED value is set but never |
| cleared.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_IRQSENABLED</span></code> indicates that interrupts have been |
| enabled. Again, during bring-up (or if there are hardware |
| problems), it is very likely that the system may crash just |
| when interrupts are enabled, leaving this setting on the LEDs. |
| This LED value is set but never cleared.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_STACKCREATED</span></code> is set each time a new stack is created. |
| If set, it means that the system attempted to start at least |
| one new thread. This LED value is set but never cleared.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_INIRQ</span></code> is set and cleared on entry and exit from each |
| interrupt. If interrupts are working okay, this LED will have a |
| dull glow.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_SIGNAL</span></code> is set and cleared on entry and exit from a |
| signal handler. Signal handlers are tricky so this is |
| especially useful during bring-up or a new architecture.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_ASSERTION</span></code> is set if an assertion occurs.</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">LED_PANIC</span></code> will blink at around 1Hz if the system panics and |
| hangs.</p></li> |
| </ul> |
| </section> |
| <section id="common-led-interfaces"> |
| <h2>Common LED interfaces<a class="headerlink" href="#common-led-interfaces" title="Permalink to this heading"></a></h2> |
| <p>The <code class="docutils literal notranslate"><span class="pre">include/nuttx/board.h</span></code> includes the following declarations:</p> |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.board_autoled_initialize"> |
| <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">board_autoled_initialize</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">void</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.board_autoled_initialize" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Called early in power-up initialization to initialize the LED hardware.</p> |
| <div class="admonition note"> |
| <p class="admonition-title">Note</p> |
| <p>In most architectures, |
| <code class="docutils literal notranslate"><span class="pre">board_autoled_initialize()</span></code> is called from board-specific |
| initialization logic. But there are a few architectures |
| where this initialization function is still called from |
| common chip architecture logic. This interface is not, |
| however, a common board interface in any event.</p> |
| </div> |
| <div class="admonition warning"> |
| <p class="admonition-title">Warning</p> |
| <p>This interface name will eventually be removed; |
| do not use it in new board ports. New implementations should |
| not use the naming convention for common board interfaces, |
| but should instead use the naming conventions for |
| microprocessor-specific interfaces or the board-specific |
| interfaces (such as <code class="docutils literal notranslate"><span class="pre">stm32_led_initialize()</span></code>).</p> |
| </div> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.board_autoled_on"> |
| <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">board_autoled_on</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">led</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.board_autoled_on" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Called to instantiate the LED |
| presentation of the event. The <code class="docutils literal notranslate"><span class="pre">led</span></code> argument is one of the |
| definitions provided in <code class="docutils literal notranslate"><span class="pre"><board-name>/include/board.h</span></code>.</p> |
| </dd></dl> |
| |
| <dl class="c function"> |
| <dt class="sig sig-object c" id="c.board_autoled_off"> |
| <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">board_autoled_off</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">led</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.board_autoled_off" title="Permalink to this definition"></a><br /></dt> |
| <dd><p>Called to terminate the LED |
| presentation of the event. The <code class="docutils literal notranslate"><span class="pre">led</span></code> argument is one of the |
| definitions provided in <code class="docutils literal notranslate"><span class="pre"><board-name>/include/board.h</span></code>. Note |
| that only <code class="docutils literal notranslate"><span class="pre">LED_INIRQ</span></code>, <code class="docutils literal notranslate"><span class="pre">LED_SIGNAL</span></code>, <code class="docutils literal notranslate"><span class="pre">LED_ASSERTION</span></code>, and |
| <code class="docutils literal notranslate"><span class="pre">LED_PANIC</span></code> indications are terminated.</p> |
| </dd></dl> |
| |
| </section> |
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