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| <div class="section" id="mynewt-faq-syntax-semantics-configuration"> |
| <h1>Mynewt FAQ - Syntax, Semantics, Configuration<a class="headerlink" href="#mynewt-faq-syntax-semantics-configuration" title="Permalink to this headline">¶</a></h1> |
| <div class="contents local topic" id="contents"> |
| <ul class="simple"> |
| <li><p><a class="reference internal" href="#floating-point-in-mynewt" id="id1">Floating Point in Mynewt</a></p></li> |
| <li><p><a class="reference internal" href="#ending-the-delay-of-a-task-blocking-a-call-early" id="id2">Ending the Delay of a Task Blocking a Call Early</a></p></li> |
| <li><p><a class="reference internal" href="#random-function-device" id="id3">Random Function / Device</a></p></li> |
| <li><p><a class="reference internal" href="#setting-serial-and-mfghash" id="id4">Setting <code class="docutils literal notranslate"><span class="pre">serial</span></code> and <code class="docutils literal notranslate"><span class="pre">mfghash</span></code></a></p></li> |
| <li><p><a class="reference internal" href="#leading-zeros-format-in-printf" id="id5">Leading Zeros Format in <code class="docutils literal notranslate"><span class="pre">printf</span></code></a></p></li> |
| <li><p><a class="reference internal" href="#mynewt-equivalent-of-unix-sleep-3" id="id6">Mynewt Equivalent of UNIX <code class="docutils literal notranslate"><span class="pre">sleep(3)</span></code></a></p></li> |
| <li><p><a class="reference internal" href="#alternatives-to-cmsis-nvic-c" id="id7">Alternatives to <code class="docutils literal notranslate"><span class="pre">cmsis_nvic.c</span></code></a></p></li> |
| </ul> |
| </div> |
| <div class="section" id="floating-point-in-mynewt"> |
| <h2><a class="toc-backref" href="#id1">Floating Point in Mynewt</a><a class="headerlink" href="#floating-point-in-mynewt" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: I am trying to print floating point in Mynewt using <code class="docutils literal notranslate"><span class="pre">console_printf("%f",</span> <span class="pre">floating_var)</span></code> but I am unable to do so. |
| How do I resolve the issue? I’m aware Mynewt uses baselibc - does it even support floating point?</p> |
| <p><strong>A</strong>: Baselibc does support floating point formatting, but it is not enabled |
| by default. To enable it, set the following syscfg setting to 1 in your |
| target: <code class="docutils literal notranslate"><span class="pre">FLOAT_USER</span></code></p> |
| <p>However, baselibc’s float printf support is a bit limited. In particular, it |
| ignores precision specifiers and always prints three digits after the |
| decimal point.</p> |
| </div> |
| <div class="section" id="ending-the-delay-of-a-task-blocking-a-call-early"> |
| <h2><a class="toc-backref" href="#id2">Ending the Delay of a Task Blocking a Call Early</a><a class="headerlink" href="#ending-the-delay-of-a-task-blocking-a-call-early" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: I have a task which is blocking on a call to <code class="docutils literal notranslate"><span class="pre">os_time_delay()</span></code>. What is the recommended way to end the delay |
| early in an ISR (e.g. button press)?</p> |
| <p><strong>A</strong>: The best way would be to use a semaphore. Initialize the semaphore with a count of 0 (<code class="docutils literal notranslate"><span class="pre">os_sem_init()</span></code>), then |
| block on the semaphore with the maximum delay you want to wait for (<code class="docutils literal notranslate"><span class="pre">os_sem_pend()</span></code>). The button press event would |
| wake the first task up early by calling <code class="docutils literal notranslate"><span class="pre">os_sem_release()</span></code>.</p> |
| </div> |
| <div class="section" id="random-function-device"> |
| <h2><a class="toc-backref" href="#id3">Random Function / Device</a><a class="headerlink" href="#random-function-device" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: Does Mynewt have a random function or random device?</p> |
| <p><strong>A</strong>: <code class="docutils literal notranslate"><span class="pre">baselibc</span></code> has <code class="docutils literal notranslate"><span class="pre">rand()</span></code>, and <code class="docutils literal notranslate"><span class="pre">crypto/tinycrypt</span></code> has <code class="docutils literal notranslate"><span class="pre">hmac-prng</span></code>.</p> |
| </div> |
| <div class="section" id="setting-serial-and-mfghash"> |
| <h2><a class="toc-backref" href="#id4">Setting <code class="docutils literal notranslate"><span class="pre">serial</span></code> and <code class="docutils literal notranslate"><span class="pre">mfghash</span></code></a><a class="headerlink" href="#setting-serial-and-mfghash" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: What is <code class="docutils literal notranslate"><span class="pre">mfghash</span></code>? How do I set <code class="docutils literal notranslate"><span class="pre">serial</span></code> and <code class="docutils literal notranslate"><span class="pre">mfghash</span></code> (currently blank in my app)?</p> |
| <p><strong>A</strong>: <code class="docutils literal notranslate"><span class="pre">mfghash</span></code> is computed if you’re using <code class="docutils literal notranslate"><span class="pre">newt</span> <span class="pre">mfg</span></code> to construct your flash image, and it identifies the build of |
| your bootloader. <code class="docutils literal notranslate"><span class="pre">newt</span> <span class="pre">mfg</span></code> bundles togetherthe bootloader, target image, and other data you’d want to bundle when creating |
| an image to burn to flash. See the <code class="docutils literal notranslate"><span class="pre">newt</span> <span class="pre">mfg</span></code> <span class="xref std std-doc">documentation</span> for the construction |
| side of things and <code class="docutils literal notranslate"><span class="pre">apache-mynewt-core/sys/mfg/src/mfg.c</span></code> for the firmware side. <code class="docutils literal notranslate"><span class="pre">serial</span></code> was intended to be used if you |
| want to have your own naming scheme per device when building products; i.e. you want something other than the mcu serial |
| number, or if you don’t have serial number available.</p> |
| </div> |
| <div class="section" id="leading-zeros-format-in-printf"> |
| <h2><a class="toc-backref" href="#id5">Leading Zeros Format in <code class="docutils literal notranslate"><span class="pre">printf</span></code></a><a class="headerlink" href="#leading-zeros-format-in-printf" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: Is there a way to make printf and console_printf honor the leading zeros format? As in:</p> |
| <p><code class="docutils literal notranslate"><span class="pre">console_printf("%.2d",</span> <span class="pre">5);</span></code></p> |
| <p>outputting “05” instead of as for me now: “2d” ?</p> |
| <p><strong>A</strong>: <code class="docutils literal notranslate"><span class="pre">console_printf("%02d",</span> <span class="pre">5);</span></code></p> |
| </div> |
| <div class="section" id="mynewt-equivalent-of-unix-sleep-3"> |
| <h2><a class="toc-backref" href="#id6">Mynewt Equivalent of UNIX <code class="docutils literal notranslate"><span class="pre">sleep(3)</span></code></a><a class="headerlink" href="#mynewt-equivalent-of-unix-sleep-3" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: Is there an equivalent to the UNIX sleep(3)?</p> |
| <p><strong>A</strong>: <code class="docutils literal notranslate"><span class="pre">os_time_delay(OS_TICKS_PER_SEC</span> <span class="pre">*</span> <span class="pre">secs)</span></code></p> |
| </div> |
| <div class="section" id="alternatives-to-cmsis-nvic-c"> |
| <h2><a class="toc-backref" href="#id7">Alternatives to <code class="docutils literal notranslate"><span class="pre">cmsis_nvic.c</span></code></a><a class="headerlink" href="#alternatives-to-cmsis-nvic-c" title="Permalink to this headline">¶</a></h2> |
| <p><strong>Q</strong>: What do I use instead of the full version of <code class="docutils literal notranslate"><span class="pre">cmsis_nvic.c</span></code> (i.e. for setting and getting IRQ priorities)?</p> |
| <p><strong>A</strong>: Those functions are in the <code class="docutils literal notranslate"><span class="pre">core_cmx.h</span></code> files in <code class="docutils literal notranslate"><span class="pre">hw/cmsis-core</span></code>.</p> |
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