is leJOS right for me

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is leJOS right for me

Postby capple » Tue Aug 05, 2014 4:29 pm

My son and i have been working a project with our "NXT" and now I may want to jump it to the EV3. The NXT robot was a slave to our Win7 PC. On this PC we have a Python script that is connected to both the NXT and a Minecraft server. Both played well with python. The Minecraft parts are from some Raspberry Pi stuff we have done with Minecraft. We created a CraftBukkit on the PC and RaspberryJuiced into the game to monitor and manipulate the game. The NXT/Minecraft stuff we have so far is proof of concept and the project is growing faster then the development. Original scope of the project was to have "Steve" push buttons in the Minecraft world. My Python scripts would monitor these button and command the NXT robot to move. Then we tested using the NXT color sensor to change the Minecraft world. Sense red->change block in Minecraft Red..You get the picture. All these functions are working well.

Now to why we want to go with the EV3.

With color sensing and Minecraft world manipulation we are thinking about abandoning the buttons in Minecraft and have the robot follow "Steve's" movements. To better sync "Steve" and the robot knowing the direction of the robot N,S,E,W would be required to keep them traveling in the same direction. We then are going to cover the table top with a grid of colored squares so we can map the environment in Minecraft.

Hardware I have today
NXT 1.0 home Parts no electronics
NXT 2.0 Home complete
EV3 Home

Will be getting from My sons school this week
NXT Education + expansion
EV3 Education **** The reason I'm looking at direction sensing

We hope to have the project to demo at the end of the month "Aug 27" at his open house. The school has asked us to bring our robots to the Open house because they are also hosting a STEM night.

I have worked in Eclipse before on some Android stuff in the past. I believe this is where leJOS works. I'm looking for a little direction so not to waste a lot of time if leJOS is the solution then I will dive in. I seen here at lejos forums a thread stating python 2.7 is now supported. This is why I'm here. I have not found any EV3-Python developed python libraries yet for PC controlled EV3's. Seem the work is on running Linux on the EV3 and python on brick.

I look forward in chatting more on this if this is the right place for me and sharing the end project too.
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Re: is leJOS right for me

Postby gloomyandy » Tue Aug 05, 2014 5:07 pm

Hi,
it is not easy to answer your questions but I'll have a go at providing some more information that may help you make up your mind
* leJOS is primarily a Java system for the EV3
* It seems that some people have used the leJOS system to provide a way to use Python on a PC to control the EV3, however this is not something that is directly supported by the leJOS team, so you really need to talk to the folks that have worked on this.
* To use leJOS you need to create a bootable sdcard and insert this into your EV3, if you remove the card then the EV3 goes back to running the standard Lego software (so you can reasonably easy try out leJOS).
* leJOS on the EV3 is a fairly complex system (certainly compared with the Lego software) and particularly at this relatively early stage. To use it you really need to be happy with Java and Eclipse. Having some Linux knowledge will also help.

Not sure if the above helps, but it is my best shot.

Andy
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Re: is leJOS right for me

Postby capple » Tue Aug 05, 2014 6:13 pm

Thank you for your reply. It is always nice to have research confirmed with live advice. I found what you talked about others used leJOS to support python. Since it looks as if I'm stuck on python I will be visiting the others you mention for further details. With software I'm a jack of all master of none. Done projects in VBA, Java, Python, C++. My career has me programming Allen Bradly or Rockwell PLC5, SLC500, and CLX5000 ladder logic. Its all the same but very different.
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Re: is leJOS right for me

Postby skoehler » Wed Aug 06, 2014 1:41 pm

It should be mentioned that we occasionally change the interface between the kernel modules and userspace programs. This means whatever python code might be out there to interface with the Lego kernel modules might not work with the leJOS kernel modules. This is an unfortunate situation, but I have the impression that the Lego kernel modules are strongly tailored to the needs of the Lego virtual machine and thus their interfaces are often not very general or flexible.
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Re: is leJOS right for me

Postby gloomyandy » Wed Aug 06, 2014 1:46 pm

Hi Sven,
the python stuff posted on the forum does not talk directly to the Lego modules, instead it uses a leJOS program that runs as a network server and the python code talks to that to read sensors, move motors etc.

Andy
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Re: is leJOS right for me

Postby skoehler » Wed Aug 06, 2014 1:59 pm

I should have clarified that I was talking about Python code running on the EV3 itself.
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Re: is leJOS right for me

Postby capple » Mon Aug 11, 2014 2:22 am

I found the Minecraft api's folder the came with Minecraft Pi edition has java folder with java API's. I have installed eclipse and was testing the EV3, Eclipse, and Minecraft. I have not figured out the Minecraft parts yet. But with some struggle got the EV3 and Eclipse to play together. Through filtering through multiple threads found my firewall was blocking the USB connection as well as I have to set up the EV3control GUI. No tutorials have guided a newbie through this process. Tested a hello world program and got it working but it downloads and runs on the brick. I am now looking for some guidance to run the code on PC so if I get the Minecraft Java working I can intermingle the two.

Thanks for your help thus far
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Re: is leJOS right for me

Postby gloomyandy » Mon Aug 11, 2014 9:16 am

Have you looked at the leJOS blog?
http://lejosnews.wordpress.com/
it has a number of posts on using the leJOS remote API from various systems to control the EV3.

Andy
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Re: is leJOS right for me

Postby capple » Thu Aug 14, 2014 6:14 am

I been back and forth to were this project is going. Python/Java/Python/Java... I'm not solid in either. I spent some time away from the EV3 to focus on my Minecraft hurdles. Seem I could get the data I wanted in Python so even my NXT-Python was hitting dead ends. Fighting through that I opened the Minecraft plugin source code to see why. You never guest the source is all in Java. Poking around there I found how to get my data I needed trough the Java plugin out to my Python. BUT wait I still realy want to run the EV3 and Gyro. Now EV3 Python seems dead but EV3 java is not and I can now easily hook into Minecraft with Java. Can you point me to some sample code using java and EV3. I been up long hours and can only find a few clips writing to the LCD. I will need remote Motor control, Color sensor monitor, and Gyro angle. I'm going to bed now walking away.
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Re: is leJOS right for me

Postby capple » Thu Aug 14, 2014 1:20 pm

Well being persistent I did get some data and motor movement but only using on brick programs. I'm going to now have to dig deep into Bluetooth control of all functions from a program running on the PC.
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Re: is leJOS right for me

Postby gloomyandy » Thu Aug 14, 2014 3:34 pm

Are you sure you want to do this via Bluetooth? WiFi is usually a better option. Even if you use Bluetooth, I would recommend that you simply create a Bluetooth PAN and use that to allow the use of the TCP/IP, RMI based remote interface rather than the older LCP/Bluetooth interface (which is really intended for allowing the EV3 to talk to an NXT).

Did you read the blog posts I pointed you at earlier that contains a lot of remote access examples. You should also look at the source of the EV3 control program. Finally rather than trying to use "Remote control" from a PC based program, you may want to create a program that runs on the EV3 and that talks to your PC based program using TCP/IP, this allows much greater flexibility than simple remote control and allows the EV3 to perform things which may need fast response times (like object detection), locally. Remember that you have access to all of the leJOS source code (for instance the EV3Control program is here: https://sourceforge.net/p/lejos/ev3/ci/ ... ev3/tools/), so there is a lot of example code.
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Re: is leJOS right for me

Postby capple » Thu Aug 14, 2014 6:12 pm

I looked through the blog but that was back when I was unsure where I was going. Not that I'm sure yet but will again revisit. You been a great support and I thank you for being so patient with me. The brick running program dose make sense. I will start to test that.
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