blob: 53084f1b81598926f7fcbdb2008c955420538f3c [file] [log] [blame]
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<!-- This is broken by doc revisioning.
-->
<link rel="shortcut icon" href="../../../../../img/favicon.ico">
<title>ADC - Apache Mynewt</title>
<link href="../../../../../css/bootstrap-3.0.3.min.css" rel="stylesheet">
<link rel="stylesheet" href="../../../../../css/highlight.css">
<link href="../../../../../css/base.css" rel="stylesheet">
<link href="../../../../../css/custom.css" rel="stylesheet">
<link href="../../../../../css/v2.css" rel="stylesheet">
<link href="https://fonts.googleapis.com/css?family=Lato" rel="stylesheet">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css">
<!-- HTML5 shim and Respond.js IE8 support of HTML5 elements and media queries -->
<!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
<script src="https://oss.maxcdn.com/libs/respond.js/1.3.0/respond.min.js"></script>
<![endif]-->
<script>
(function(i, s, o, g, r, a, m) {
i["GoogleAnalyticsObject"] = r;
(i[r] =
i[r] ||
function() {
(i[r].q = i[r].q || []).push(arguments);
}),
(i[r].l = 1 * new Date());
(a = s.createElement(o)), (m = s.getElementsByTagName(o)[0]);
a.async = 1;
a.src = g;
m.parentNode.insertBefore(a, m);
})(window, document, "script", "//www.google-analytics.com/analytics.js", "ga");
ga("create", "UA-72162311-1", "auto");
ga("send", "pageview");
</script>
</head>
<body class="ADC">
<div class="container">
<div class="row v2-main-banner">
<a class="logo-cell" href="/">
<img class="logo" src="/img/logo.png">
</a>
<div class="tagline-cell">
<h4 class="tagline">An OS to build, deploy and securely manage billions of devices</h4>
</div>
<div class="news-cell">
<div class="well">
<h4>Latest News:</h4> <a href="/download">Apache Mynewt 1.11.0, Apache NimBLE 1.6.0 </a> released (September 7, 2023)
</div>
</div>
</div>
</div>
<nav id="navbar" class="navbar navbar-inverse affix-top" data-spy="affix" data-offset-top="150" role="navigation">
<div class="container">
<!-- Collapsed navigation -->
<div class="navbar-header">
<!-- Expander button -->
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
</div>
<!-- Expanded navigation -->
<div class="navbar-collapse collapse">
<!-- Main navigation -->
<ul class="nav navbar-nav navbar-right">
<li
class=""
>
<a href="/"><i class="fa fa-home" style="font-size: larger;"></i></a>
</li>
<li
class="important"
>
<a href="/quick-start/">Quick Start</a>
</li>
<li
class=""
>
<a href="/about/">About</a>
</li>
<li
class=""
>
<a href="/talks/">Talks</a>
</li>
<li
class="active"
>
<a href="/documentation/">Documentation</a>
</li>
<li
class=""
>
<a href="/download/">Download</a>
</li>
<li
class=""
>
<a href="/community/">Community</a>
</li>
<li
class=""
>
<a href="/events/">Events</a>
</li>
</ul>
</div>
</div>
</nav>
<div class="container">
<div class="row">
<div class="col-md-3 v2-sidebar sidebar-container"><div id="docSidebar" class="hidden-print" role="complementary">
<div class="top">
<div role="search">
<form id="rtd-search-form" class="wy-form" action="../../../../../search.html" method="get">
<div class="form-group">
<input type="text" name="q" class="form-control" placeholder="Search documentation" />
</div>
</form>
</div>
</div>
<ul class="toc-nav">
<li class="doc-version"><select class="form-control" onchange="if (this.value) window.location.href=this.value">
<option value="/latest">
Version: master
</option>
<option value="/v1_11_0/" >
Version: 1.11.0
</option>
<option value="/v1_10_0/" >
Version: 1.10.0
</option>
<option value="/v1_9_0/" >
Version: 1.9.0
</option>
<option value="/v1_8_0/" >
Version: 1.8.0
</option>
<option value="/v1_7_0/" >
Version: 1.7.0
</option>
<option value="/v1_6_0/" >
Version: 1.6.0
</option>
<option value="/v1_5_0/" >
Version: 1.5.0
</option>
<option value="/v1_4_0/" >
Version: 1.4.0
</option>
<option value="/v1_3_0/os/introduction" >
Version: 1.3.0
</option>
<option value="/v1_2_0/os/introduction" >
Version: 1.2.0
</option>
<option value="/v1_1_0/os/introduction" >
Version: 1.1.0
</option>
<option value="/v1_0_0/os/introduction" >
Version: 1.0.0
</option>
<option value="/v0_9_0/os/introduction" selected="selected" >
Version: 0.9.0
</option>
</select></li>
<li ><a href="../../../../introduction/">Mynewt Documentation</a>
<ul>
<li ><a href="../../../../get_started/get_started/">Basic Setup</a>
</li>
<li >
<a href="../../../../get_started/vocabulary/">Concepts</a>
</li>
<li ><a href="../../../../tutorials/tutorials/">Tutorials</a>
</li>
<li ><a href="../../../../os_user_guide/">OS User Guide</a>
<ul>
<li ><a href="../../../../core_os/mynewt_os/">OS Core</a>
</li>
<li ><a href="../../../../core_os/porting/port_os/">Porting to your Platform</a>
</li>
<li ><a href="../../../console/console/">Console</a>
</li>
<li ><a href="../../../shell/shell/">Shell</a>
</li>
<li ><a href="../../../bootloader/bootloader/">Bootloader</a>
</li>
<li><a href="
../../../fs/fs/fs/
">File System</a>
</li>
<li ><a href="../../hal/">Hardware Abstraction Layer</a>
<ul>
<li >
<a href="../../hal_architecture/">Architecture</a>
</li>
<li><a href="
../../hal_api/
">API</a>
<ul>
<li >
<a href="../../hal_api/">Summary</a>
</li>
<li class="active">
<a href="./">ADC</a>
</li>
<li >
<a href="../../hal_cputime/hal_cpu_timer/">CPU timer</a>
</li>
<li >
<a href="../../hal_dac/hal_dac/">DAC</a>
</li>
<li><a href="
../../hal_flash/hal_flash/
">Flash memory</a>
</li>
<li >
<a href="../../hal_gpio/hal_gpio/">GPIO</a>
</li>
<li >
<a href="../../hal_i2c/hal_i2c/">I2C</a>
</li>
<li >
<a href="../../hal_pwm/hal_pwm/">PWM</a>
</li>
<li >
<a href="../../hal_spi/hal_spi/">SPI</a>
</li>
<li >
<a href="../../hal_system/hal_sys/">System</a>
</li>
<li >
<a href="../../hal_uart/hal_uart/">UART</a>
</li>
</ul>
</li>
<li >
<a href="../../hal_in_libraries/">Using HAL</a>
</li>
<li >
<a href="../../hal_creation/">Creating HAL</a>
</li>
</ul>
</li>
<li ><a href="../../../testutil/testutil/">Test Utilities</a>
</li>
<li ><a href="../../../imgmgr/imgmgr/">Image Manager</a>
</li>
<li >
<a href="../../../baselibc/">Baselibc library</a>
</li>
<li ><a href="../../../elua/elua/">Embedded Lua</a>
</li>
<li ><a href="../../../json/json/">JSON</a>
</li>
<li ><a href="../../../stats/stats/">Stats</a>
</li>
<li ><a href="../../../logs/logs/">Logs</a>
</li>
</ul>
</li>
<li><a href="
../../../../../network/ble/ble_intro/
">BLE User Guide</a>
</li>
<li ><a href="../../../../../newt/newt_intro/">Newt Tool Guide</a>
</li>
<li ><a href="../../../../../newtmgr/overview/">Newt Manager Guide</a>
</li>
<li >
<a href="../../../../../known_issues/">Known Issues</a>
</li>
</ul>
</li>
<li><a href="
../../../../../faq/how_to_edit_docs/
">Appendix</a>
</li>
</ul>
</div></div>
<div class="col-md-9" role="main">
<div class="doc-header">
<div role="navigation" aria-label="breadcrumbs navigation">
<ul class="wy-breadcrumbs">
<li><a href="/documentation/">Docs</a></li>
<li>&raquo; <a href="os/modules/hal/hal_api/">API</a></li>
<li>&raquo; <a href="os/modules/hal/hal/">Hardware Abstraction Layer</a></li>
<li>&raquo; <a href="os/os_user_guide/">OS User Guide</a></li>
<li>&raquo; <a href="os/introduction/">Mynewt Documentation</a></li>
<li>&raquo; ADC</li>
</ul>
</div>
</div>
<div class="alert alert-warning">
<p>
Version 0.9.0 is not the most recent version of the Apache Mynewt
documentation. Click <a href="/latest">here</a> to read the latest
version.
</p>
</div>
<h1 id="hal_adc">hal_adc</h1>
<p>The hardware independent interface to Analog To Digital Controllers</p>
<h3 id="description">Description</h3>
<p>Analog to Digital converters (ADCs) read analog values (voltage) and convert
them to digital values to be used in your applications. For a description
of ADC, see <a href="https://en.wikipedia.org/wiki/Analog-to-digital_converter">wikipedia</a></p>
<h3 id="definition">Definition</h3>
<p><a href="https://github.com/apache/incubator-mynewt-larva/blob/master/hw/hal/include/hal/hal_adc.h">hal_adc.h</a></p>
<h3 id="hal_adcs-theory-of-operation">HAL_ADCs Theory Of Operation</h3>
<p>ADCs have different conversion rates, resolution (bits) and reference voltages.</p>
<p>The HAL_ADC has APIs to allow the application or library to query the capabilities
of a specific ADC.</p>
<table>
<thead>
<tr>
<th><strong>Method Name</strong></th>
<th>** Description **</th>
</tr>
</thead>
<tbody>
<tr>
<td>hal_adc_get_bits</td>
<td>gets the resolution of the ADC in bits. For example if the ADC is 10 bits, a read will return a value from 0 through 2^10 - 1 = 1023.</td>
</tr>
<tr>
<td>hal_adc_get_ref_mv</td>
<td>gets the underlying reference voltage for the ADC in millivolts. For example, if the ADC is 10 bits and the reference voltage is 5000 mV a ADC reading of 1023 corresponds to 5V; a ADC reading of 0 corresponds to 0 volts.</td>
</tr>
</tbody>
</table>
<p>Given this information, the application or library could convert any reading
to millivolts. Since this is a common operation, the HAL_ADC API has a helper
function to perform this function: <code>hal_adc_to_mv()</code>.</p>
<p>The current HAL_ADC API provides a blocking read command to initiate an ADC
conversion, and return the result of that conversion. Conversion time is
hardware dependent, but this is not an instantaneous operation. Libraries
can use the <a href="../../hal_cputime/hal_cpu_timer/">hal_cputime</a> APIs to
time conversions if that is relevant to the application.</p>
<p>Future HAL_ADC APIs will include periodic ADC conversion, non-blocking ADC
conversion and direct-to-memory DMA conversion. </p>
<div class="row">
<ul class="nav nav-pills" style="margin-bottom: 10px">
<li>
</li>
<li class="pull-right">
</li>
</ul>
</div>
<footer class="row">
<div class="col-xs-12">
<p class="copyright">Apache Mynewt (incubating) is available under Apache License, version 2.0.</p>
</div>
<div class="col-xs-12">
<div class="logos">
<a href="https://www.apache.org/">
<img src="/img/asf_logo_wide_small.png" alt="Apache" title="Apache">
</a>
<p>
Copyright © 2015-2021 The Apache Software Foundation.<br>
<small class="footnote">
Apache Mynewt, Mynewt, Apache, the Apache feather logo, and the Apache Mynewt
project logo are either registered trademarks or trademarks of the Apache
Software Foundation in the United States and other countries.
</small>
</p>
<a href="">
<img src="https://www.countit.com/images/add_to_slack.png" alt="Slack Icon" title="Join our Slack Community" />
</a>
</div>
</div>
<a href="https://www.apache.org/licenses/">
<button class="button-footer-asf">
License
</button>
</a>
<a href="https://www.apache.org/foundation/sponsorship.html">
<button class="button-footer-asf">
Sponsorship
</button>
</a>
<a href="https://www.apache.org/foundation/thanks.html">
<button class="button-footer-asf">
Thanks
</button>
</a>
<a href="https://www.apache.org/security/">
<button class="button-footer-asf">
Security
</button>
</a>
<a href="https://apache.org/events/current-event">
<button class="button-footer-asf">
ASF Events
</button>
</a>
</footer>
</div>
</div>
</div>
<script src="../../../../../js/jquery-1.10.2.min.js"></script>
<script src="../../../../../js/bootstrap-3.0.3.min.js"></script>
<script src="../../../../../js/highlight.pack.js"></script>
<script src="../../../../../js/base.js"></script>
<script src="../../../../../js/custom.js"></script>
<script src="search/main.js"></script>
</body>
</html>