Questions tagged [lejos]
A Java Virtual Machine that can run on Mindstorms intelligent bricks.
15 questions
1
vote
0
answers
100
views
Unable to open port error
Since today, no matter what program that uses sensors I try to run on my EV3 I get the following error:
lejos.hardware.DeviceException: unable to open port
at lejos.internal.ev3.EV3Port.open(...
- 11
4
votes
1
answer
565
views
Stuck on "Installing rootfs" when installing leJOS on the brick
When following the instructions for creating an SD card with leJOS, the brick freezes when it comes to the screen “Installing rootfs.” I'm using a new 32 GB SanDisk SD card. I've confirmed that I'm ...
- 191
3
votes
1
answer
661
views
Two motors are driven forward, why are they rotating in different directions?
I have the Lego Mindstorms EV3 Pack and built a simple car with 3 wheels. The back wheels are motorized.
When I run the following code:
Motor.A.backward();
Motor.D.Backward();
both motors are ...
- 41
2
votes
0
answers
410
views
Is there an leJOS simulator for EV3?
I found this but this seems to be using their own library to control the EV3.
- 21
3
votes
2
answers
780
views
How to get leJOS to run on macOS Sierra
I am working with an eclipse plugin that requires it to run 32bit Java 6 on it and I do have Java 6 on my computer but when I run the program I get this error.
Error: This Java instance does not ...
- 133
1
vote
0
answers
751
views
EV3 connection problem via USB on Windows 8.1
I am using LEGO EV3 on windows 8.1 eclipse Neon. When I try to launch the class as a LeJos application I get this error.
IP address is /10.0.1.1
Creating the jar file or uploading the program failed
...
- 11
2
votes
0
answers
2k
views
Bluetooth connection to EV3 from Java on Linux/Android
I would like to connect to my EV3 from PC (and then Android) via Bluetooth.
I was able to connect to NXT with LEGO-MINDSTORMS-MINDdroid which uses direct LCP commands but as far as I know the ...
- 121
1
vote
1
answer
2k
views
Where can I find a good tutorial on programming with Lejos?
I want to get started with LeJOS and use Java to check to see if an EV3 touch sensor is pressed, but I can't find any decent tutorials. Are there any good resources for this?
- 81
3
votes
0
answers
951
views
Sending Gcode to LEGO Mindstorms X/Y plotter?
I am building an x/y plotter out of LEGO Mindstorms. I would like it to read an SVG file on the EV3 Brick, convert it to Gcode, and draw the coordinates. How would I go about doing this?
- 81
2
votes
1
answer
236
views
Java BufferedImage with Lejos NXT: Java Heap Space
I'm trying to write a program for my Lego Mindstorm NXT, the program is simple, drawing some lines and saving the image in a .png file. So, I thought I'd use BufferedImage and use getGraphics to draw ...
- 23
0
votes
1
answer
403
views
LEGO Mindstorm NXT memorize line followed (LeJos)
I made a line follower program with leJos, it works pretty well; and I want to take it to the next level: I want to make it remember the line it followed; works like this: follow the line till the end,...
- 23
2
votes
1
answer
2k
views
usage of ev3 ultrasonic sensor in lejos behavior based programming
I'm using ev3 ultrasonic sensor. And I'm writing a behavior based lejos code. I want to do some tasks when the ultrasonic sensor detects an object which is not further than 30 cm's. And this is my ...
- 121
4
votes
0
answers
500
views
RCX + java + usb-to-serial
I am trying to get an old RCX working with leJOS. I already have it working with NQC and BricxCC.
While NCQ/BricxCC seems to recognize my usb-to-serial (which appears as "COM5" to the OS), the leJOS ...
- 91
6
votes
1
answer
495
views
EV3 RMIregulatedMotor Regulation Problems
I have problem with regulation of the motor when I control EV3 with Bluetooth.
Here is the code:
RemoteEV3 ev3 = new RemoteEV3("10.0.1.1");
ev3.setDefault();
RMIRegulatedMotor leftMotor = ev3....
- 257
7
votes
1
answer
2k
views
How to close color Sensor properly?
I want to get data from the color sensor with Bluetooth. I can get data but when the program terminates, the color sensor dose not close even though I call function close() on the color sensor. The ...
- 257