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<table class="head">
<tr>
<td class="head-ltitle">DS3231(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">DS3231(4)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">ds3231</code> — <span class="Nd">Extremely
Accurate i2c-integrated real-time clock (RTC)/TCXO/Crystal</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">device iic</code>
<br/>
<code class="Cd">device iicbus</code>
<br/>
<code class="Cd">device ds3231</code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">ds3231</code> is a low-cost, extremely
accurate I2C realtime clock (RTC) with an integrated temperature-compensated
crystal oscillator (TCXO) and crystal.</p>
<p class="Pp">The device incorporates a battery input and maintains accurate
timekeeping when main power to the device is interrupted.</p>
<p class="Pp">Access to <code class="Nm">ds3231</code> data is made with the
<a class="Xr">sysctl(8)</a> interface:</p>
<div class="Bd Pp Li">
<pre>dev.ds3231.0.%desc: Maxim DS3231 RTC
dev.ds3231.0.%driver: ds3231
dev.ds3231.0.%location: addr=0xd0
dev.ds3231.0.%pnpinfo: name=rtc compat=maxim,ds3231
dev.ds3231.0.%parent: iicbus1
dev.ds3231.0.temperature: 23.2C
dev.ds3231.0.temp_conv: 0
dev.ds3231.0.bbsqw: 0
dev.ds3231.0.sqw_freq: 8192
dev.ds3231.0.sqw_mode: interrupt
dev.ds3231.0.32khz_enable: 1</pre>
</div>
<dl class="Bl-tag">
<dt id="dev.ds3231._d.temperature"><var class="Va">dev.ds3231.%d.temperature</var></dt>
<dd>The read-only value of the current temperature read by the RTC.</dd>
<dt id="dev.ds3231._d.temp_conv"><var class="Va">dev.ds3231.%d.temp_conv</var></dt>
<dd>Start a new temperature conversion. When read as 1, a temperature
conversion is in progress. When read as 0 and then set to 1, a temperature
conversion is started. The temperature conversion runs automatically on
power up and once every 64 seconds afterward.</dd>
<dt id="dev.ds3231._d.bbsqw"><var class="Va">dev.ds3231.%d.bbsqw</var></dt>
<dd>If set to 1 and <var class="Va">dev.ds3231.%d.sqw_mode</var> is set to
square-wave, battery-backed square-wave output is enabled. If set to 0,
the SQW pin will be set to high impendance when the RTC is being powered
by battery.</dd>
<dt id="dev.ds3231._d.sqw_freq"><var class="Va">dev.ds3231.%d.sqw_freq</var></dt>
<dd>Select the frequency of the SQW pin when the square-wave output is enabled
on <var class="Va">dev.ds3231.%d.sqw_mode</var>. It can be set to 1, 1024,
4096, and 8192.</dd>
<dt id="dev.ds3231._d.sqw_mode"><var class="Va">dev.ds3231.%d.sqw_mode</var></dt>
<dd>Set the operation mode for the SQW pin. It can be set to 'interrupt'
(default) or 'square-wave'. In interrupt mode, the SQW pin is used to
generate interrupts for the RTC alarms. In square-wave mode, the SQW pin
drives a square-wave of <var class="Va">dev.ds3231.%d.sqw_freq</var>
frequency.</dd>
<dt id="dev.ds3231._d.32khz_enable"><var class="Va">dev.ds3231.%d.32khz_enable</var></dt>
<dd>Enable the 32kHz output.</dd>
</dl>
<p class="Pp">Please check the <code class="Nm">ds3231</code> datasheet for more
details.</p>
<p class="Pp">On a <a class="Xr">device.hints(5)</a> based system, such as
<code class="Li">MIPS</code>, these values are configurable for
<code class="Nm">ds3231</code>:</p>
<dl class="Bl-tag">
<dt id="hint.ds3231._d.at"><var class="Va">hint.ds3231.%d.at</var></dt>
<dd>The <a class="Xr">iicbus(4)</a> that the <code class="Nm">ds3231</code> is
connected to.</dd>
<dt id="hint.ds3231._d.addr"><var class="Va">hint.ds3231.%d.addr</var></dt>
<dd>The 8-bit i2c address of <code class="Nm">ds3231</code>. The default 8-bit
address for <code class="Nm">ds3231</code> is 0xd0.</dd>
</dl>
<p class="Pp">On a <a class="Xr">FDT(4)</a> based system the following
properties must be set:</p>
<dl class="Bl-tag">
<dt id="compatible"><var class="Va">compatible</var></dt>
<dd>Must always be set to "maxim,ds3231".</dd>
<dt id="reg"><var class="Va">reg</var></dt>
<dd>The 7-bit i2c address of <code class="Nm">ds3231</code>. The default 7-bit
address for <code class="Nm">ds3231</code> is 0x68.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">fdt(4)</a>, <a class="Xr">iic(4)</a>,
<a class="Xr">iicbus(4)</a>, <a class="Xr">sysctl(8)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">ds3231</code> driver first appeared in
<span class="Ux">FreeBSD 11.0</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">The <code class="Nm">ds3231</code> driver and this manual page
were written by <span class="An">Luiz Otavio O Souza</span>
<<a class="Mt" href="mailto:loos@FreeBSD.org">loos@FreeBSD.org</a>>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">December 10, 2024</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
