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Update the porting guide

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Gregory Nutt
2015-11-20 08:43:19 -06:00
parent 5ab7c50a23
commit e4d0255c14
1 changed files with 15 additions and 3 deletions
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Documentation/NuttxPortingGuide.html
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@@ -12,7 +12,7 @@
<h1><big><font color="#3c34ec">
<i>NuttX RTOS Porting Guide</i>
</font></big></h1>
<p>Last Updated: May 18, 2015</p>
<p>Last Updated: November 20, 2015</p>
</td>
</tr>
</table>
@@ -2340,6 +2340,14 @@ else
<dt><code>CONFIG_RTC</code>
<dd>Enables general support for a hardware RTC.
Specific architectures may require other specific settings.
<dt><code>CONFIG_RTC_EXTERNAL</code>
<dd>Most MCUs include RTC hardware built into the chip.
Other RTCs, <i>external</i> MCUs, may be provided as separate chips typically
interfacing with the MCU via a serial interface such as SPI or I2C.
These external RTCs differ from the builtin RTCs in that they cannot be initialized
until the operating system is fully booted and can support the required serial
communications. <code>CONFIG_RTC_EXTERNAL</code> will configure the operating
system so that it defers initialization of its time facilities.
<dt><code>CONFIG_RTC_DATETIME</code>
<dd>There are two general types of RTC: (1) A simple battery backed counter that keeps the time when power
is down, and (2) A full date / time RTC the provides the date and time information, often in BCD format.
@@ -2364,8 +2372,12 @@ else
</p>
<ul>
<li><code>up_rtc_initialize()</code>.
Initialize the hardware RTC per the selected configuration.
This function is called once during the OS initialization sequence
Initialize the builtin, MCU hardware RTC per the selected configuration.
This function is called once very early in the OS initialization sequence.
NOTE that initialization of external RTC hardware that depends on the
availability of OS resources (such as SPI or I2C) must be deferred
until the system has fully booted. Other, RTC-specific initialization
functions are used in that case.
</li>
<li><code>up_rtc_time()</code>.
Get the current time in seconds. This is similar to the standard <code>time()</code> function.