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Using Java X10 to get Status Request from CM11

Posted on 2006-11-27
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I'm currently using Java X10 API (http://x10.homelinux.org/docs/) that utilized JavaComm (http://java.sun.com/products/javacomm/reference/api/index.html) to communicate with a CM11 device that's connected to my computer throught a serial port.

Here's the protocol that CM11 uses (http://www.x10pro.com/pro/pdf/cm11a_protocol.txt).

I've managed to send out X10 signals to a AM12 device connected to a standing fan to make it on/off. I'm now trying to send a Status Request command to the CM11 (0x8b), and apparently the CM11 sends data back to me through the serial port which i read off using the inputbuffer/outputbuffer.

I need to get bit range 31-16 as defined in the CM11 protocol so that i can monitor if a device is switched on/off from the byte that i picked off the inputbuffer.
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Question by:timlow84
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6 Comments
 
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girionis earned 500 total points
ID: 18018187
How many bytes is the response? You usually right shift the value in order to get the bits seperately, for example if you have a short value (16 bits) you would do something like the following in order to break it into two bytes

short value = ...;
byte left = (byte) (value >>> 8);
byte right = (byte) value;

Likewise you should do for the bits 16-31, to get the bits from 23 to 31 you would do something like

(byte) (value >>> 24)

and so on.
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Expert Comment

by:girionis
ID: 18018309
> to get the bits from 23 to 31

I meant from 24 to 31.
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by:timlow84
ID: 18025221
Upon sending the status command, i would get 16 bytes back... and the status request is

--------------------------------------------------------------------------------------
        # Bit range      Description
      # 111 to 96      Battery timer (set to 0xffff on reset)                   (Byte 0-1)
      # 95 to 88      Current time (seconds)                                  (Byte 2 )
      # 87 to 80      Current time (minutes ranging from 0 to 119)      (Byte 3)
      # 79 to 72      Current time (hours/2, ranging from 0 to 11)       (Byte 4)
      # 71 to 63      Current year day (MSB bit 63)                         (Byte 5+)
      # 62 to 56      Day mask (SMTWTFS)                              (Byte 6-)
      # 55 to 52      Monitored house code                                 (Byte 7 lo)
      # 51 to 48      Firmware revision level 0 to 15                           (Byte 7 hi)
      # 47 to 32      Currently addressed monitored devices              (Byte 8-9)
      # 31 to 16      On / Off status of the monitored devices         (Byte 10-11)
      # 15 to 0       Dim status of the monitored devices                 (Byte 12-13)
--------------------------------------------------------------------------------------

Scenario: i'm reading data off the inputstream in a thread... if i detect nothing in the outputstream, i'll attempt to read incoming data... here's a sniplet of my code...

public class CM11ASerialController implements Runnable, Controller
{
    private DataInputStream fromX10;
    public static final byte TIME_POLL = ((byte) 0xA5);
    public static final byte DATA_POLL = ((byte) 0x5A);
    ...
    ...

    public void run()
    {
        byte nextByte = (byte) fromX10.readByte();

                switch(nextByte)
            {
                    // detect that a status request is sent, and handle the status request
                    // in a function handleStatusRequest();
                case TIME_POLL : setInterfaceTime();
                    break;
                case DATA_POLL : handleData();
                    break;
                default : handleChecksum(nextByte);
            }
            if (running && (fromX10.available() == 0))
            {
                System.out.println("Sending data from SerialPort to Interface");
                initiateNextCommand();
            }
    ...
}

i want to be able to...
(1) detect that a status request, and then pass the byte to a function in which i'll handle the data
(2) inside the function where i'm able to get the On / Off status of the monitored devices throught [bit range 31 to 16] / [Byte 10-11]...
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LVL 35

Expert Comment

by:girionis
ID: 18025967
You have to do it like I said in my first comment, right shift the value you need as many positions as the number of the bits you want to get.
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