ERROR ev3dev.utils.Sysfs - File: '/sys/class/tacho-motor/motor9/command' without write permissions. #554
Description
Have installed ev3dev on debian stretch on my EV3 Brick and tried the sample program
example.robotics.ev3.actuator.motor.BasicMotorOperationExample from yesterday's template-project-gradle:
package example.robotics.ev3.actuator.motor;
import ev3dev.actuators.lego.motors.EV3LargeRegulatedMotor;
import lejos.hardware.port.MotorPort;
import lejos.utility.Delay;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
class BasicMotorOperationExample {
public static final EV3LargeRegulatedMotor mA = new EV3LargeRegulatedMotor(MotorPort.B);
public static Logger LOGGER = LoggerFactory.getLogger(BasicMotorOperationExample.class);
public static int DELAY = 2000; //2 Seconds
public static void main(String[] args) {
mA.brake();
LOGGER.info("Starting motor on B");
mA.setSpeed(500);
LOGGER.info("Forward");
mA.forward();
LOGGER.info("Large Motor is moving: {}, at speed {}", mA.isMoving(), mA.getSpeed());
Delay.msDelay(DELAY);
LOGGER.info("Stop");
mA.stop();
LOGGER.info("Large Motor is moving: {}, at speed {}", mA.isMoving(), mA.getSpeed());
Delay.msDelay(DELAY);
LOGGER.info("Backward");
mA.backward();
LOGGER.info("Large Motor is moving: {}, at speed {}", mA.isMoving(), mA.getSpeed());
Delay.msDelay(2000);
LOGGER.info("Stop");
mA.stop();
LOGGER.info("Large Motor is moving: {}, at speed {}", mA.isMoving(), mA.getSpeed());
Delay.msDelay(DELAY);
LOGGER.info("Forward");
mA.forward();
Delay.msDelay(2000);
mA.stop();
LOGGER.info("Stop");
}
}On the ssh console I get this:
> Task :remoteRun
java -server -jar /home/robot/EV3dev_Examples-all-0.3.0.jar
ev3dev#27|2018-11-07 11:51:05 [main] DEBUG ev3dev.hardware.EV3DevDistros - Debian Stretch detected
ev3dev#27|2018-11-07 11:51:06 [main] DEBUG ev3dev.hardware.EV3DevDistros - Debian Stretch detected
ev3dev#27|2018-11-07 11:51:06 [main] DEBUG ev3dev.hardware.EV3DevFileSystem - Root Path: /sys/class
ev3dev#27|2018-11-07 11:51:07 [main] INFO e.a.lego.motors.BaseRegulatedMotor - Configuring motor connected on Port: B
ev3dev#27|2018-11-07 11:51:07 [main] DEBUG e.a.lego.motors.BaseRegulatedMotor - Detecting motor on port: ev3-ports:outB
ev3dev#27|2018-11-07 11:51:07 [main] DEBUG ev3dev.hardware.EV3DevDevice - Detected device on path: /sys/class/lego-port/port5/address, ev3-ports:outB
ev3dev#27|2018-11-07 11:51:07 [main] DEBUG e.a.lego.motors.BaseRegulatedMotor - Setting port in mode: tacho-motor
ev3dev#27|2018-11-07 11:51:08 [main] DEBUG ev3dev.hardware.EV3DevDevice - Detected device on path: /sys/class/tacho-motor/motor9/address, ev3-ports:outB
ev3dev#27|2018-11-07 11:51:09 [main] ERROR ev3dev.utils.Sysfs - File: '/sys/class/tacho-motor/motor9/command' without write permissions.
ev3dev#27|Exception in thread "main" java.lang.ExceptionInInitializerError
ev3dev#27|Caused by: java.lang.RuntimeException: Operation not executed: /sys/class/tacho-motor/motor9/command with value reset
ev3dev#27| at ev3dev.hardware.EV3DevDevice.setStringAttribute(EV3DevDevice.java:118)
ev3dev#27| at ev3dev.actuators.lego.motors.BaseRegulatedMotor.<init>(BaseRegulatedMotor.java:94)
ev3dev#27| at ev3dev.actuators.lego.motors.EV3LargeRegulatedMotor.<init>(EV3LargeRegulatedMotor.java:26)
ev3dev#27| at example.robotics.ev3.actuator.motor.BasicMotorOperationExample.<clinit>(BasicMotorOperationExample.java:16)
Java Runtime:
openjdk version "10" 2018-03-20
OpenJDK Runtime Environment (build 10+46-ev3)
OpenJDK Client VM (build 10+46-ev3, mixed mode, sharing)
Main libraries:
- ev3dev-lang-java-2.4.7-SNAPSHOT.jar
- lejos-commons-0.7.1.jar
However, it works on Oracle Java 8
java version "1.8.0"
Java(TM) SE Embedded Runtime Environment (build 1.8.0-b132, headless)
Java HotSpot(TM) Embedded Client VM (build 25.0-b70, mixed mode)