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172 lines
8.0 KiB
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172 lines
8.0 KiB
Plaintext
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<meta name="generator" content="HTML Tidy for HTML5 for Apple macOS version 5.8.0">
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<title>JMRI Hardware Setup Support - Raspberry Pi GPIO</title>
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<meta name="author" content="Paul Bender">
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<meta name="keywords" content="Raspberry Pi GPIO Configuration Information for JMRI">
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<h1>Hardware Setup Support: Raspberry Pi via GPIO</h1>
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<p>The <a href="https://www.raspberrypi.org/" target="_blank">Raspberry Pi</a> is a family of
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inexpensive credit card size single board computers that have many applications in embedded
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electronics. This page describes the use of the Raspberry Pi's GPIO pins under JMRI. Since
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the Raspberry Pi runs Linux natively, other connections are also possible using either a
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<a href="../USBtoSerial.shtml">USB connection</a> or via the Raspberry Pi's built in serial
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ports.</p>
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<img src="images/Pi2ModB1GB_-comp.jpg" alt=
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"Raspberry Pi2 model B (courtesy www.raspberrypi.org" width="528" height="300" class=
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"floatRight" title="Pi2 model B (© www.raspberrypi.org)"> <a id="hardware"></a>
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<p class="noted">See <a href="https://www.jmri.org/install/Raspbian.shtml">here for information</a>
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on how to install JMRI on a Raspberry Pi under the Raspian operating system. This must be
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done before using Raspberry Pi GPIO pins with JMRI objects.</p>
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<h2>Supported Hardware</h2>
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<p>Theoretically, any Raspberry Pi supported by <a href="https://pi4j.com/" target=
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"_blank">Pi4J</a> is supported by JMRI.<br>
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JMRI support has been tested with the Models B, B+, 2B, and 3. There's also a <a href=
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"https://www.jmri.org/install/Raspbian.shtml">JMRI install help page for the Pi</a>.</p>
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<h2 id="connecting">Connecting</h2>
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<p>Underlying support for the Raspberry Pi's GPIO connections is provided using the <a href=
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"https://pi4j.com/">Pi4J library for Java</a>.</p>
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<p><strong>Version 1.0 of the Pi4J Library, used with JMRI version 4.5.4 and earlier,
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<em>require that applications using GPIO pins be run as root (or using
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<code>sudo</code></em></strong>).</p>
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<p><strong>Starting with version 4.5.5, JMRI uses version 1.1 of the Pi4J Library. Version
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1.1 of the Pi4J library, <em>when used in conjunction with Raspbian Jessie (and later
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releases)</em> allow the user to access the GPIO pins without running as root. For
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compatability reasons, and to allow possible use of PWM outputs, JMRI has choosen not to
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enable this mode by default.</strong>
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</p>
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<p><strong><em>In order to enable use of the GPIO pins by a non-root user, the user must set
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the <code>WIRINGPI_GPIOMEM</code> environment variable as follows:</em></strong>
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</p>
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<p><code>export WIRINGPI_GPIOMEM=1</code>
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</p>
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<p><strong>This environment varialbe must be set prior to executing JMRI</strong>
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</p>
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.
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<p>For more information, please see the relavent portions of <a href=
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"http://www.savagehomeautomation.com/projects/pi4j-now-supports-non-privileged-access-no-more-rootsudo.html"
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target="_blank">the pi4j web page</a>.</p>
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<h3>Pi4j 1.1 and Raspbian Stretch</h3>
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<p>It has been brought to our attention that the linux kernel used in Raspbian Stretch and
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Pi4j version 1.1 have a slight incompatability. This incompatability is caused by Pi4J's
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interface with the hardware is doesn't recognize the CPU reported by the kernel. This section
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describes how to determine if you are experiencing this issue and how to correct the problem
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on your Raspberry Pi.</p>
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<h4>Determining if the incompatability is a problem</h4>
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<p>If the incompatability is an issue, JMRI will crash when attempting to create a Raspberry
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Pi connection and the following error message will appear in the console log:</p>
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<pre style="font-family: monospace;">
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Unable to determine hardware version. I see: Hardware : BCM2835
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,
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- expecting BCM2708 or BCM2709.
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If this is a genuine Raspberry Pi then please report this
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to projects@drogon.net. If this is not a Raspberry Pi then you
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are on your own as wiringPi is designed to support the
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Raspberry Pi ONLY.
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</pre>
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<h4>How to correct for this issue</h4>
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<p>To correct for this issue, there are two steps you need to complete. First, you need to
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install a recent version of the wiringPi library, whic Pi4J uses to talk to the Raspberry
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Pi's hardware. You can do this by running the following command in a terminal:</p>
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<p><code>sudo apt-get install wiringpi</code>
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</p>
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<p>Second, we need to configure Pi4j to use the library you just installed instead of the one
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that is included with Pi4j. To tell JMRI to use Pi4j in this mode, we are going need to run
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the following command in a terminal as the user who starts the JMRI application(s):</p>
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<p><code>echo "default_options=\"-Dpi4j.linking=dynamic\"" > ~/.jmri/jmri.conf</code>
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</p>
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<p>After completing these steps, JMRI will be able to configure and use Raspberry Pi hardware
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normally.</p>
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<h3>Wiring</h3>
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<p>JMRI currently supports inputs (Sensors) and outputs (Turnouts) via the Raspberry Pi's
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GPIO pins.</p>
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<h4>Input/Output pin addressing</h4>
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<p>JMRI currently uses the default Pi4J pin numbering. The Pin numbers may differ on each
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model Pi. Generally speaking, Broadcom GPIO pins 0 to 7 may be referenced by those pin
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numbers in JMRI. This is not guaranteed to be the case. Higher pin numbers are available, but
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may not correspond to the Broadcom pin numberings. Please refer to the <a href=
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"https://pi4j.com/">Pi4J website</a> for model specific pin numbering information.</p>
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<h3>Settings</h3>
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<ol>
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<li>Make sure you have the latest version of JMRI installed, then go to the Preferences
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panel of a JMRI-based program. This opens automatically the first time a program is run, or
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you can select it from the "Edit" menu</li>
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<li>Select "Raspberry Pi Foundation" from the System Manufacturer selection box.</li>
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<li>Select "Raspberry Pi GPIO" from the System Connection selection box. <!--
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<li> The "Connection Prefix" is used to help JMRI communicate
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separately with multiple "connections" to layout hardware. Each
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"connection" must have a unique identifier, which is specified as
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the "Connection Prefix". By default, the first Pi connection is
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given a prefix of "P", and additional Pi networks are given
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prefixes like "P1", "P2", ... Most users should be able to use the
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default "Connection Prefix" value provided by the JMRI tools.
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<li>When a JMRI tool is configured for more than one connection,
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each connection gets a menu item on the main JMRI tool window. To
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help users differentiate between their different connections, each
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connection has a "Connection Name", which is used as the name of
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the associated menu item on the main JMRI tool window. Users may
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change the "Connection Name" for any connection to suit their needs.
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--></li>
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<li>Click "Save". You'll be asked if it's OK for the program to quit, click "Yes".</li>
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<li>Restart the program. You should be up and running.</li>
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</ol>
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<h2 id="documentation">Documentation</h2>
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<h3>JMRI Help</h3>
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<p><a href="https://www.jmri.org/install/Raspbian.shtml">JMRI installation on Pi/Raspbian</a>.</p>
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<h3>Third Party info</h3>
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<p>The <a href="https://pi4j.com/" target="_blank">Pi4J website</a> provides model specific
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Java I/O information.</p>
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