Order of JAVA ME on Raspberry PI software servo with/dev/servoblaster

Long post:
I use JAVA ME on Raspberry PI to drive the different engines and a robot sensors, everything works fine, but also wanted to do servos from the software. Apparently I can't do it directly by the control of length of puls of software on an operating system such as Raspberry PI, too vague. So, I tried to switch to the use of servoblaster that uses the DMA access to control the pulse duration. It works fine when it is called from python or command line, but now, I want to call from JAVA ME program.
For this I need to write some simple arrangements to/dev/servoblaster.
After start, l - ls/dev/servoblaster shows:
PRW-rw-rw-1 root root 0 Feb 8 16:55 / dev/servoblaster
I tried to use the following code, with a few expressions of feeling between the two, to open the servoblaster that I can then send values to him to drive the servos:

ServoPath path = FileSystems.getDefault().getPath("/dev","servoblaster");
System.out.println ("set path" + servoPath.toString ());
outStream = Files.newOutputStream (servoPath, WRITE);
System.out.println ("created outstream");

Also, I tried another method in JAVA ME 8 with the following code. The two options are the MOOC on JAVA ME course.
connection = (FileConnection)
Connector.Open ("file:///rootfs/dev/servoblaster", Connector.WRITE);
System.out.println ("connection opened");
fileWriter = new PrintStream (connection.openOutputStream ());
System.out.println ("filewriter started");

In both cases, the statements will fail on the line 3rd , that is the opening of the OutputStream. I get an error on the invoice, pro forma raspberry:

[CRITICAL] [SECURITY] iso = 2:Permission check failed: java.io.FilePermission "/ dev/servoblaster" "write".
TRACK: java.security.AccessControlException: >, lanceApp generated an Exception
Although I defined the following permissions
java.io.FilePermission "/ *" 'write '.
and
javax.microedition.io.Connector.file.write
javax.microedition.io.Connector.file.read

So far, my conclusion is that fails because JAVA ME8 does not support a PipedOutputStream
My other option would be to escape from the command line, make echo/dev/servoblaster settings and then return to the JAVA ME program
but I found that JAVA ME also does not support the runtime exec command so I can't do that.
So my only option now seems to be to move to JAVA SE. I tried servoblaster of JAVA SE and that works very well, I just open it and send data to it, servo reacts, no problem. But then, I still need to control other motors and sensors.

I then tried install libraries open jdk.dio on the IP, so I can still use what I've done so far, but the installation instructions are not clear to me, and do not work.

So now I'm moving away from JAVA ME and move to JAVA SE with PI4J, unless someone here can help me out.

Thank you
Willem

Hi Willem.

That's right, JavaME can open only normal files (link, pipes, blocks, char, FIFO, and socket is not supported).

/ Sergey

Tags: Java

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