OK, so another piece of the control puzzle may be falling into place. I purchased two small 5v relays off eBay. These should allow me to use the outgoing signals from the Raspberry Pi to control things like power to switches, signals or other on-off devices. Since the relays totally isolate the Pi from whatever is being controlled, I don’t have to worry about too much voltage flowing back into the Pi and killing it. The biggest problem, and something I need to work out, is that these are really meant to be triggered at 5 volts where the Pi only puts out 3.3 volts. I have heard it will work, but only testing will tell.
I also bought a small breadboard, something that is amazing that I never had before, some connecting wires, and a Adafruit T-Cobler connector board. Oh, and a 16×2 HD44780 LED display that I want to use to have the Pi constantly output its status and network address.
Finally, since it falls into the same vein, kind of, I will be going to the Palmetto Open Source Software Conference next week in Columbia, SC. I am going for work due to Linux administration, web servers, and other open source software, but it will be good to SparkFun folks who are doing some Open Hardware demos. Puzzle me that one Batman!
Oh! And lastly, because I like cool links, a list of the top 10 things (so far) to hook up to your Raspberry Pi.
And now my little Raspberry Pi has wi-fi. This is the next step in moving towards a self contained JMRI unit. I chose the Edimax EW-7811Un USB wireless adapter because it is cheap and very small. So small that it doesn’t block the second USB port, doesn’t stick out very far, and doesn’t require extra power or place an heavy draw on the Pi.
All I did was power down the Pi, insert the little Edimax unit, reboot the Pi, and then go into a VNC session over the connected ethernet connection. I did it that way because I don’t have a monitor or keyboard directly connected, and the graphical setup for the wi-fi adapter is much easier than doing it from the command line.
You can see from the screenshot at left that the graphical wi-fi setup is dirt simple. Just launch it, have it scan for your SSID (or type it in yourself if it isn’t broadcast), select it and enter your wireless password. That’s it. Or, at least that is for supported devices that have the drivers built–in to the Raspbian operating system build. Again, that is one of the reasons I purchased this one – so I wouldn’t have to mess with finding driers. And at just $13, I wasn’t going to get anything any cheaper anyway.
So now I can take the Ethernet cord out, move my Pi anywhere in the house, and continue work on the project via wi-fi. Next will be a small external display to show some machine stats (cost of LED display ~$6.00 off eBay) and then work on the actual machine to track DCC interface.
Might as well add in here too that I went to a lecture put on by the South Carolina Historical Society this even. The first half was on railroad first of SC, such as The Best Friend. The second have was about historical resources available in the Library of Congress from an engineering survey and audit of all the railroads in the US done around 1920 or so. Good stuff, and great references for modeling. I am going to try to get in touch with the two speakers to not only get more information for my modeling of the Seaboard Air Line Railroad in this area, but also for further information and resources to add to my Charleston Rail site.
My Raspberry PI is now safe and sound in its new case. And it has a new 16 gig class 10 SD card! Oh, and heat sinks on the three main hot spots. Yes, I am having fun. The USB wifi adapter for it should be here Tuesday or Wednesday.
Well, thanks to the help of some instructions and code I found on line cleverly named “JMR-PI“, I now have JMRI up and running on my Raspberry Pi. Truth be told, it really didn’t take much effort on my part. All I had to do was follow the instructions Matthew Macdonald-Wallace put up on the GitHub repository. If I am able to make any additions to contributions to the project, I will also put them up online.
But, now that JMRI is up and operational, I need to work on the Pi to track interface, be it SPROG or Digtrax PR3 or whatever. No reason to delay and no time to waste.
Oh, also just a quick not that I did purchase a case for my Pi. I just can’t stand to have it sitting out all nekkid-like. I don’t know if this will be its permanent home, but it was cheap and also came with some heat sinks for the main chips.
I got it off eBay for less than $9 including the case, heat sinks, and shipping. Can’t beat that even if I don’t end up using it for anything more than initial protection and prototyping.
So after following a few pointers, I came across the Michael Blank’s SimpleDCC site. The cool thing about this is that he is using an Arduino as a DCC control unit without something like the SPROG as in interface. He is have the Arduino itself send out the DCC signal alone with a booster to power the trains. I need to study both his interface and the programming some more, a lot more, but it really does hold out the hope that I can either use just the Raspberry Pi with an Arduino, or even just the Pi all by itself, to be a complete JMRI/DCC controller.
Guess what I really need to do too is dig some more into the JRMI code and the Linux installation. I don’t know whether it would be easer and faster to use the Arduino hooked up to the Raspberry Pi to do the translation to DCC, or whether I should have the Pi do that also. Another consideration that starts to come in is the speed of that entire process. But then again, that is what experimenting is there to find out.