Kotlin Mindstorms EV3 Bot

Or "stuffing modern tech into an old LEGO ev3 to see if it works while cackling like a mad scientist."

Bugs

Needs the path. jrun -cp "/home/lejos/programs/kev3-1.0-SNAPSHOT.jar:/home/root/lejos/lib/*" info.benjaminhill.kev3.MainKt
Caliko is compiled with JDK11. Recompiled locally with JDK8.
Issue with HTTPS/SSL. date -s "2021-07-29 05:31:00"
Code deploy run loop is too many commands.
java.lang.UnsupportedOperationException: Remote regulators are not supported
Missing the JNA dependency will make you smack face on keyboard. Tried removing extra jna.

Setup LeJOS (Java 1.8) on EV3

Latest LeJOS
Reformat ~2gb microSD disk as MS DOS (FAT) to avoid permission bug in balena etcher
Flash sd500.img as a nice baseline.
unzip the lejosimage.zip file from the leJOS home directory to the root directory of the card
You want JRE 1.8. The webpage has 1.7. 😖
Grab ejdk1.8.0. From: Java 8 support - leJOS (don't forget that -g, it matters!)
- export JAVA_HOME=$(/usr/libexec/java_home -v1.8)
- ./jrecreate.sh -g --dest ejre-8-b132-linux-arm-sflt --profile compact2 --vm client
- tar czf ejre-8-b132-linux-arm-sflt.tar.gz ejre-8-b132-linux-arm-sflt
- Move that tar.gz file to the root of the card along with everything else
- Boot EV3. Let the potato rest for 5 minutes.

ssh -c aes256-cbc  -oKexAlgorithms=+diffie-hellman-group1-sha1 root@192.168.86.45
# (no pw)
root@EV3:/# /home/root/lejos/ejre-8-b132-linux-arm-sflt/bin/java -version
# java version "1.8.0"
# Java(TM) SE Embedded Runtime Environment (build 1.8.0-b132, profile compact2, headless)

... all looks good!

Setup Local Dev Env

Latest IntelliJ IDE, create a new app: Kotlin > Console App > JRE 1.8 (creates a pom.xml)

Or clone https://github.com/salamanders/kev3

mvn versions:display-dependency-updates # then fix outdated stuff
mvn dependency:copy-dependencies # which creates target/dependency folder of the jars you need!

If you need inverse kinematics, but Caliko is not on maven central

# from the caliko ./target/ folder: 
mvn install:install-file \
  -DgroupId=au.edu.federation.caliko \
  -DartifactId=caliko \
  -Dversion=1.3.8 \
  -Dfile=caliko-1.3.8.jar \
  -DgeneratePom=true \
  -Dpackaging=jar

Load the script from a web service

cd kev3bot-server
firebase init
# In the FireBase console, create your empty Firestore Database, fill in your own PROJECT_ID and API_KEY.

The ev3's wifi dongle is... not fast. (maybe 20KB/sec). You will want to 1-time copy over all the files from mvn dependency:copy-dependencies to the robot, so each time you build/deploy/test you only have to move the very small app-code only jar file over. Do this whenever you update your maven dependencies.

scp -c aes256-cbc -oKexAlgorithms=+diffie-hellman-group1-sha1 ./target/dependency/*.jar root@192.168.86.45:/home/root/lejos/lib/
# no password

Every time you want to test some code:

mvn deploy
mvn antrun:run

Or you can do it from a ssh:

jrun -cp "/home/lejos/programs/kev3-1.0-SNAPSHOT.jar:/home/root/lejos/lib/*" info.benjaminhill.kev3.MainKt

salamanders/kev3bot