JMRI on a Raspberry Pi 2

[Sherman]

WARNING: This is a long post and concerns computer stuff so many people may find it boring!

So, I've been running JMRI on an old laptop running Windows XP for the WiThrottle feature. The problem is that the laptop is so old that
it doesn't have the option of WPA wireless which is what the new wireless router at home is running. I could just use a long Ethernet
cable from the laptop to the network switch (and in fact that is what I've been doing) but it is a hassle. It is time to retire the old
laptop but I don't want to give up JMRI and I don't have another spare computer to use. What to do? Aha! A Raspberry Pi could do the
trick! In case you haven't heard of it the Raspberry Pi is a $35 single board computer about the size of a credit card that runs various
operating systems but a version of Debian Linux called Raspian is what is recommended and what I decided to use.

Great news- a new version of the Raspberry Pi called the Raspberry Pi 2 is available. It has a faster four core processor rather than the
original single core processor and 1GB of RAM rather than the 512MB of the previous model. The best part? The price is still $35! Of
course $35 gets you a bare board without a case, power supply, keyboard, monitor or anything else. I decided to go for a "kit" which
included a power supply, a case, heat sinks, a USB Wifi dongle, an HDMI cable and an 8GB microSD card containing NOOBS (New Out of Box
Software) which enables you to install an operating system. The cost of all that is still only $69. The RPi2 uses a microSD card rather
than a disk drive for booting up. If you need or want more storage you can get a larger card or you can connect storage to one of the Pi
2's four USB ports. For running JMRI an 8GB card is more than sufficient (and cheap). MicroSD cards are available in different "classes"
with the higher numbers being faster. I use Class 10 cards.

When I received the RPi2 I connected it to one of our televisions via the included HDMI cable. I plugged the Wifi dongle into a USB port
and connected a USB keyboard (I have a couple laying around) and a USB mouse (ditto). I then inserted the microSD card and plugged in the
power supply to turn it on, there is no on/off switch. The RPi2 booted up using the NOOBS and then presented a menu of choices regarding
installing the OS. I chose the Raspian system and also chose the boot to GUI option. The RPi2 then went ahead and installed the OS and
set up the space on the microSD card. You should change the default password but even if you do if you choose the boot to GUI option it
will boot up to the graphical user interface without requiring the password. That isn't the most secure way to do it but since mine will
just be running JMRI it won't be an issue. I will also be running the RPi2 "headless", that is without a monitor attached (and in fact I
probably won't have a keyboard or mouse attached either). So there would be no way to exploit the system even with physical access to it.

Once the OS was installed, a process that takes about 10 minutes, I updated and upgraded the system. From the terminal type "sudo apt-get
upgrade" and hit enter. Some messages will appear and when the prompt returns type "sudo apt-get update". The update command might take
a few minutes to complete. This insures you have the latest version of Raspian and any included software. Since Java is already
installed the next step is to install JMRI. There are a few ways to go about getting JMRI and installing it but perhaps the easiest way
is to use a pre-written script available at https://github.com/proffalken/JMR-Pi which downloads and uncompresses JMRI, creates a JMRI
user and puts everything in the proper directory.

One issue that Raspberry Pi users run into is that JMRI requires a package called RXTXcomm. It is included with JMRI but the version
included does not work on the Raspberry Pi. That means you must install the package from scratch and then replace the file included with
JMRI with the one in the newly installed package. (A file named RXTXcomm.jar should be copied to the /opt/JMRI/lib folder.)
Once I had JMRI and the supporting packages installed I plugged in my Digitrax PR3 to the remaining USB port (remember I used one for
Wifi, one for the keyboard and one for the mouse). I then started JMRI and it opened at the "Preferences" window where I selected
"Digitrax" for the interface manufacturer and PR3 as the interface. From the drop-down menu I was able to select the USB port the PR3 was
plugged into. Finally I selected the Command Station I have (Zephyr). If you don't have your interface connected to the RPi2 and powered
up when you start JMRI you will get an error indicating the hardware wasn't found. Also you need an external power supply for the
interface because the RPi2 USB ports can only supply about 100mA of current.

I wanted a JMRI icon on the RPi desktop so I looked up how that is done. I'm not a Linux guru by any stretch so I generally have to look
up procedures and commands. It turns out a text file with four lines in it saved to the "Desktop" directory is all it takes to put the
icon there. I tested it by double-clicking on it and JMRI started. Cool. With JMRI running I started WiThrottle and set it to use a
fixed port. I just told it to use the port it was using when it started. Remember this number! Using a fixed port means you don't have
to check the WiThrottle window each time it starts to get the port number. That is important since I won't have a monitor attached to the
RPi to be able to check the port number.

Since I want to run the RPi headless I need a way to log in to it remotely so I can update it, and because I haven't written a script to
start JMRI on startup I also need to start JMRI. The solution turns out to be stunningly simple. I installed "xrdp". The "x" stands
for, well, "X", the windowing system used by Linux distributions. The "rdp" stands for "Remote Desktop Protocol". Once xrdp is installed
you need to know the IP address of the RPi. There are multiple ways to get that so I won't go into it here. Now from a Windows computer
you just run a program called "mstsc" which is included with Windows 7 and 8. I put a shortcut to it on my Windows desktop. When mstsc
runs you will see a window asking for the computer you want to log into. Enter the IP address of the RPi in that box and click "Connect".
It should find the RPi and the RPi desktop will appear on your Windows computer. You can now literally do anything on the RPi that you
can do while sitting at it with the exception of course of anything that requires you to actually touch the RPi. The even better news is
that there are RDP clients available for Android tablets and phones. I imagine that they are also available for Apple products but since
I don't use Apple computers or tablets I don't know. So you can log in to the RPi from a tablet if needed.

Time to move the RPi down to the basement and connect it to the layout. I shut down the RPi unplugged the HDMI cable and carried
everything downstairs. I have temporarily put the RPi on my desk in the basement. Eventually it will be mounted somewhere on the layout.
I plugged the PR3 into the Zephyr using a long LocoNet cable, turned on the power to the layout and Zephyr then powered up the RPi. Not
having a monitor connected to it I couldn't see what was happening but it appeared to boot up normally. I logged in to the RPi from a
cheap $39 Android tablet and there was the RPi desktop. I double tapped the JMRI icon and JMRI started, I guess actually I started
"DecoderPro". Once DecoderPro was up and running I started WiThrottle.

Now the moment of truth. I went through all this basically so I could use WiThrottle. So on my cheap tablet I started "Engine Driver"
which is a free app that connects to the JMRI WiThrottle. I entered the IP address and port number of the throttle (that's the number you
remembered from earlier) and tapped "Connect". The connect screen cleared and I was presented with the WiThrottle loco selection screen.
I entered the address of the loco that was on the track at the time and tapped "Aquire". That screen cleared and the operating screen
appeared. So far so good! Next I tapped the "Light" button on the tablet and the loco headlight came on. Sweet! I tapped "Forward" and
then used the slider to open the throttle and the loco began to move. I had full throttle, light and direction control wirelessly.
Excellent. After playing a bit and verifying WiThrottle was working well I left the RPi running, grabbed my cheat-sheet that lists all my
locos and their information such as DCC address numbers, decoder types, road name, road number and model and headed upstairs.

Upstairs I plopped down on my couch with my Windows 8 laptop, fired up mstsc and logged in to the RPi from my Windows machine. I opened
JMRI and entered my locos into the JMRI roster. It is nice being able to do that sitting on a comfy couch. After entering the locos I
grabbed my larger Galaxy Tab and headed back downstairs. I started Engine Driver on the Galaxy Tab, entered the IP and port number of the
Pi and connected to WiThrottle. Now all my locos appeared in a list and I just tapped one to select it. Engine Driver allows you to
control two locos at once so I aquired a second loco and began moving both of them around the layout. Everything worked as it should. I
now have three wireless throttles (my cheapo tablet, my better tablet and my Android phone) that work perfectly with WiThrottle in JMRI.
At this point I don't have any of my switches controlled by DCC or anything else other than the locos. If I did I am confident that the
setup I have going at this point would control them. Since I already had the PR3, tablets and phone and had a keyboard, mouse and TV I
could connect the RPi to for setup purposes the entire cost of the setup was the $69 that the RPi cost. Cheaper than buying a Digitrax
wireless connection point and wireless throttle.

A caveat- to those not familiar with Linux and used to the Plug and Play world of Windows or Macs getting everything to run on a Raspberry
Pi can be a bit of a challenge. The RPi uses an ARM7 processor and Raspian is an optimized (modified) version of Debian Linux so
everything that runs on Debian won't necessarily run on an RPi. That was the issue with the RXTXcomm package. But if you have some Linux
experience or are a patient, methodical person you should be able to get this up and running pretty quickly.

--Sherman

[pbechard]

Sherman - great write up, thank you. I've thought about the RPi2 for JMRI and WiThrottle, but it's too far down the priority list. This gives me a pretty good idea of the effort involved.

[TwinDad]

Awesome writeup, Sherman. I am seriously considering doing this for the layout control computer for my new layout. Even though I'll have a perfectly good Mac Mini sitting in the room right underneath the layout. Just for the fun of it.

One point, though. I'm pretty sure if you set both the WiThrottle server and app to "automatic" configuration, you don't have to worry about using a fixed port number. The server will advertise the service and the app will find it.

[mr_mike_m]

Thanks for testing this out for me Sherman!
This is exactly what I want to include with my portable power box for T-TRAK set ups.

[conrailandrew]

Awesome!!! I've been wanting to do this very thing, but always had a bit of trepidation about getting into it. This might be the tipping point to get me moving on it!
Thank you!!!
Andrew

[Sherman]

...One point, though. I'm pretty sure if you set both the WiThrottle server and app to "automatic" configuration, you don't have to worry about using a fixed port number. The server will advertise the service and the app will find it.

TD,
You are probably right about that. I have a Windows network in the house and none of the Windows computers can "see" the RPi2 though the RPi2 can see all the Windows machines. I wasn't sure if that would affect the WiThrottle server so I went with the fixed port. (I also set up the RPi2 with a fixed IP address for the same reason.) I actually didn't bother to test it. Maybe something for the future.


--Sherman

[TwinDad]

TD,
You are probably right about that. I have a Windows network in the house and none of the Windows computers can "see" the RPi2 though the RPi2 can see all the Windows machines. I wasn't sure if that would affect the WiThrottle server so I went with the fixed port. (I also set up the RPi2 with a fixed IP address for the same reason.) I actually didn't bother to test it. Maybe something for the future.


--Sherman

Well, there's nothing wrong with using a fixed port, either. If it ain't broke...

[Sherman]

Thanks for the kind words everyone! I think the RPi2 has great potential for use in model railroading.

1- Running JMRI as in the OP.
2- There is a port to plug in a camera and it can easily run a webserver. Remote operation anyone?
3- Connect it to a screen and program a fast clock.
4- Automate things on the layout. I'm considering writing a script to turn on layout lights and other features.
5- The RPi2 has GPIO (General Purpose Input Output) pins. That means it can receive feedback or sense things on the layout and can be programmed to respond. (Signal control?)
6- It has a pretty decent audio system. Plug in external speakers and add sound to the layout.
7- It can be connected to an Arduino to take advantage of the even more numerous GPIO pins on the Arduino and to control it via scripts or Java programs.

There are probably tons more things that could be useful on a layout or in the train room. Plus it is so cheap (1/2 the price of a DC locomotive or about 2 box cars) that one might use multiple RPi2s each one devoted to one specific task.

--Sherman

[mr_mike_m]

Kicking myself now for not picking up RPi and an Arduino at my local Radio Shack when they were blowing everything out the door at 50% off.

[mrbmac]

Nice write up Sherman. I actually have a couple of RPis laying around. I will have to give this a go once I get my NCE USB adapter.

It's actually possible to run your whole DCC system through an arduino and an RPi. there is a whole community dedicated to getting this working.

One question, woudl you be able to have the WiThrottle app do all the aux fucntions like loco sounds and all that? Also, would it be able to control turnouts that are on DCC? It would be nice to do all this just from the WiThrottle app and not need to have a screen for JMRI.

[Sherman]

One question, woudl you be able to have the WiThrottle app do all the aux fucntions like loco sounds and all that? Also, would it be able to control turnouts that are on DCC? It would be nice to do all this just from the WiThrottle app and not need to have a screen for JMRI.

mrbmac,

Engine Driver has all the buttons that you find on a throttle so you can control all the loco functions. I don't have a monitor connected to the RPi2 and I can control any loco feature via the Engine Driver software through WiThrottle. If I have to reboot the RPi2 for any reason I log into it from a different computer or tablet and do it that way. No need for a screen, keyboard or mouse on the RPi2 except for during the initial set up of the operating system and downloading the "xrdp" software. Once that is done no screen is necessary.

I don't have turnouts controlled by DCC so I haven't even looked at the possibility of doing that via the WiThrottle server but I don't see a "switch" button on Engine Driver so perhaps you would have to control switches from the JMRI console?

--Sherman

[TwinDad]

Nice write up Sherman. I actually have a couple of RPis laying around. I will have to give this a go once I get my NCE USB adapter.

It's actually possible to run your whole DCC system through an arduino and an RPi. there is a whole community dedicated to getting this working.

One question, woudl you be able to have the WiThrottle app do all the aux fucntions like loco sounds and all that? Also, would it be able to control turnouts that are on DCC? It would be nice to do all this just from the WiThrottle app and not need to have a screen for JMRI.

WiThrottle can control turnouts and routes that are defined in JMRI. It also has the same function buttons as a regular throttle, so you can control the lights and sounds that are assigned to throttle buttons.

I don't know if it has ... shall we call them "soft controls" ... that could be assigned to special functions within JMRI, but you could define an internal "turnout" in JMRI that triggers Logix or whatever to do just about anything.

It would be nice if WiThrottle included a browser screen to access JMRI panels from within the app.

[mrbmac]

Well thats pretty cool then. Essentially WiThrottle could replace my PowerCab. I guess I would still need to plug it in though to provide power to the buss.... but I would much rather use an iPhone.

[LarryDG]

Thanks for this write up Sherman! I am utterly new tow to Linux, Rasberry Pi2 and following your steps has helped out a lot!

I was wondering if you could elaborate more on this part:

One issue that Raspberry Pi users run into is that JMRI requires a package called RXTXcomm. It is included with JMRI but the version
included does not work on the Raspberry Pi. That means you must install the package from scratch and then replace the file included with
JMRI with the one in the newly installed package. (A file named RXTXcomm.jar should be copied to the /opt/JMRI/lib folder.)

I found the RXTXcomm.jar file, but not sure where to unpack it to. Do I just open it in the folder that I found it in (mentioned above).

Thanks for any further info!Sincerely,

LarryDG

[TwinDad]

I came back across this thread while setting up a Raspberry Pi Zero W for my club, and since it is both (a) very good and (b) linked to from the official JMRI website, I thought I'd add a few updates.

In the intervening three years since @Sherman made the original post, updates to both JMRI and Raspbian OS have made this process SIGNIFICANTLY easier.

With the current version of Raspbian ("Stretch") and the most recent versions of JMRI (certainly 4.14, most likely any 4.x release), the install boils down to this:

1) Install Raspbian (or NOOBS) OS onto the Raspberry Pi. This is now a nearly fully automated process about as easy as installing Windows, maybe easier.
2) Open a browser, go to the jmri.org website, and download the Linux version of the current release of JMRI
3) Double click the Zip file and use the archive tool that pops up to extract JMRI to your favored location (I usually just put it on the desktop).
4) Inside the JMRI folder, double click DecoderPro or PanelPro to launch the application.

Yes, it is now as easy to put JMRI on a Pi as it is to put it on a Windows or Mac machine. There are a few important points to note:

* There is no need to use a special script or anything to install JMRI. Just download the Zip file directly from jmri.org and extract it as-is.
* There is no need to update or replace RXTXcomm. JMRI has moved to a different package that does not require any updates to work on the Pi.

Also, for remote desktop access, this is now (better) integrated into Raspbian out-of-the box. Just open Preferences->Raspberry PI Configuration, go to the Interfaces tab and click "Enable" next to "VNC". For folks who like to use terminal shells, you might also enable "SSH", but Raspbian will really want you to change your password if you do. Again, there is no longer a need to install any other packages or (in this case) even open a terminal.

Sherman's instructions were great, and/but I'm really happy that both the Raspbian and JMRI teams have (independently) made changes in the intervening years to make this process as smooth and easy as installing a "retail" application on a "retail" operating system. We live in good times, my friends.

[TwinDad]

Incidentally, if you are fond of the Digitrax LNWI or MRC Prodigy WiFi devices but really wish you could connect more than four (or eight) phones at a time without buying multiple devices...

You can quite easily set up a Raspberry Pi 3B+ or Zero W as its own Wirelesss Access Point (WAP) running JMRI's WiThrottle server and host as many as 254* phones at a time. And with a little bit more work you can set it up as a bridge so your phones will still have internet access while connected.

There's a very straightforward tutorial on the Raspberry Pi website for setting up Access Point mode, and once that's done, you just run JMRI and it works**!


* I can't vouch for the performance with that many client phones, but I do expect it to easily handle more phones than the LNWI.

** Also note while in stand-alone AP mode, the Pi itself won't have internet access, so you'd have to turn off AP mode and reconnect to the "house" wifi as a client to update software and such things. This process is not as well documented as the AP mode setup, but it isn't terribly hard. I believe (but haven't tested) that if set up in bridge mode, this isn't an issue, as the Pi would still have internet access while also being an AP.

[pbender]

* I can't vouch for the performance with that many client phones, but I do expect it to easily handle more phones than the LNWI.

The biggest issue with using the Pi as an access point is one of power. Especially in a noisy (at 2.4GHz ) environment, the Pi as an access point doesn’t work as well as a dedicated access point. At home the Pi by itself is generally ok, but if I want it at a show, I take one of my old house routers with me and just connect a Pi to it via Ethernet ( this won’t work for a Pi Zero obviously).

I suspect the LNWI has similar issues, but you don’t have the option to connect it to an external access point.

[TwinDad]

The biggest issue with using the Pi as an access point is one of power. Especially in a noisy (at 2.4GHz ) environment, the Pi as an access point doesn’t work as well as a dedicated access point. At home the Pi by itself is generally ok, but if I want it at a show, I take one of my old house routers with me and just connect a Pi to it via Ethernet ( this won’t work for a Pi Zero obviously).

I suspect the LNWI has similar issues, but you don’t have the option to connect it to an external access point.

Fair point. I wouldn't expect the range to be all that great. My club is interested in the "wow" factor of using "cool stuff" like the Pi and the Arduino when they do demonstrations at the library and at things like the local university Engineering Day. These spaces can still be fairly noisy, but the size of the layout and the required range are much smaller. For the bigger convention layouts my recommendation was (like you) to use a traditional router.

I haven't actually tried it out in these "public but small" environments though. We have a couple of events coming up soon that will be the first run. I plan to have one of my older routers in the go bag as a backup.

One thing that can help is that the 3B+ supports the (somewhat) less crowded 5GHz band...

[Heiko]

Incidentally, if you are fond of the Digitrax LNWI or MRC Prodigy WiFi devices but really wish you could connect more than four (or eight) phones at a time without buying multiple devices...

You can quite easily set up a Raspberry Pi 3B+ or Zero W as its own Wirelesss Access Point (WAP) running JMRI's WiThrottle server and host as many as 254* phones at a time.

This is made even easier by Steve Todd, who prepares an SD card image with everything already setup: https://mstevetodd.com/rpi

I haven't tried it, since I don't have a leftover Pi but I'm using an old Netbook for the task, but everyone I've read seems happy
Heiko

[TwinDad]

This is made even easier by Steve Todd, who prepares an SD card image with everything already setup: https://mstevetodd.com/rpi

I haven't tried it, since I don't have a leftover Pi but I'm using an old Netbook for the task, but everyone I've read seems happy
Heiko

I'm going to have to try this out some time. Looks like a really convenient setup.