Running a simple experiment

Installing a node image

In this section we install the TinyOS 2 Oscilloscope application on a set of Tmote Sky nodes in the TKN TWIST testbed. The Oscilloscope application is described in the TinyOS 2 tutorial 5. After you have compiled the application with make telosb open a web browser and access the TWIST web interface. Press the "Login" button, enter your username and password and then click on "Sign in". If you have not yet registered a TWIST user account take a look at this tutorial page.

You will see a welcome page where you have three options: manage and update your account settings ("My Info"), schedule and control jobs in the testbed ("Jobs") or logout ("Logout"). Click on "Jobs" and you will see a list of scheduled jobs, i.e. the currently active jobs as well as pending future jobs. Take a close look at the list and find a time period for which Tmote/TelosB nodes are not reserved by someone else. Then click on "Add" and you will see the Job Management page as follows:

Under "Platforms" select Tmote; then choose a "Start/End date" and "Start/End time" such that the time interval is not overlapping with other jobs, which you checked in the previous step. You cannot make a real mistake here, because the system will automatically check for and not permit jobs that are overlapping in time if they use the same mote platform. However, different platforms (eyesIFX vs. Tmote) may be used concurrently. In the field "Description" enter a short note on what you plan to do in your job, such as "Testing the T2 Oscilloscope application", then click on "Add". If the time interval that you entered was accepted you will be taken back to the list of scheduled jobs, otherwise you get an error message and need to adapt the values.

The list of "Scheduled jobs" should now include your job. Your entry is likely to have gray background colour, meaning that it is registered but not yet active. The current system time is always shown in the upper right corner of the page and once your job becomes active -- its start time is shown in the column "Start" -- the background colour of your entry will turn yellow (you need to click the reload button of your browser).

When your job is active apply a tick mark at the left side of the entry and press the "Control" button at the bottom (the "Edit" button would be used to change the time of your job and with the "Delete" button you can remove your job).

Hint: When your job is active (during a experiment) you can still extend its "End time" by clicking on "Edit" on the "Jobs" page, provided that the new "End time" does not overlap with other registered jobs.

After you have clicked the "Control" button you will see the page for controlling your active job as shown in this figure:

This page is divided into the list of Tmote node IDs available in the testbed ("Available reserved resources"), a section for submitting up to three different program images to be programmed on a subset of the nodes ("Job configuration") and a set of buttons (on the bottom, not shown in Figure 3) to perform some actions, such as installing the image(s) on the nodes.

For the TinyOS 2 Oscilloscope application we want to install the Oscilloscope program image on some Tmote nodes, and one node will need to act as gateway and will be programmed with the TinyOS 2 BaseStation application (see TinyOS 2 tutorial 5). Because we will install two different application images, in the "Job configuration" field we will use two of the three "Control group" sections: the "Control group 1" section for the Oscilloscope application and the "Control group 2" section for the BaseStation application.

In the "Control group 1" section, enter in the "Node list" field a whitespace-separated list of the node IDs on which the the Oscilloscope is to be programmed, let's say 10 11 12. For convenience you can copy & paste from the list of IDs shown on top in the "Available reserved resources" list.

Then click on the "browse..." button next to the "Image" field just below the "Node list" field. Select the Oscilloscope image, which is the main.exe in your local tinyos-2.x/apps/Oscilloscope/build/telosb (you must have compiled the Oscillocope application with "make telosb" before). The "SF Baudrate" and "SF Version" fields control whether a SerialForwarder will be started for all nodes in the respective "Node list". Since we only need a SerialForwarder for the BaseStation application, we don't change the values (leaving it "None", "TinyOS 2.x"). Finally, "Channel" is the IEEE 802.15.4 channel to be used by the Tmote Sky radio CC2420 (if you change the channel for the Oscilloscope application, make sure that you do the same for the BaseStation application). In fact, the value of the CC2420_DEF_CHANNEL symbol inside your progam image will be replaced by the value of the "channel" field and thus, if your application includes the TinyOS 2 CC2420 radio stack, you can still modify the default radio channel after you have compiled the image.

Hint: The node ID is another symbol that is modified for each node individually before programming the image. It is accessible via TOS_NODE_ID in a TinyOS application.

We use the "Control group 2" section for installing the BaseStation program image on another node. In the "Node list" field enter 13 (or whichever node ID you want to use for the BaseStation application) and under "Image" click "browse..." and select the main.exe from your local tinyos-2.x/apps/BaseStation/build/telosb folder (you must have compiled the BaseStation application with "make telosb" before). Because we want to later establish a serial connection to the BaseStation node, select the pull-down menu under the "SF Baudrate" field and choose a serial baudrate. Whenever this field has a value other than None a SerialForwarder will be started for all nodes in the respective "Node list". The default baud rate for the "TelosA", ",TelosB" and "Tmote" platforms is 115200 baud.

Hint: You can change the baud rate for a telos node by modifying tinyos-2.x/tos/platforms/telosa/TelosSerialP.nc (this file is included by telosa, telosb and tmote platform). Make sure you recompile your application after changing the file.

The "SF Version" field defines the version of the Serial Forwarder protocol. Because we are using a TinyOS 2 applications select "2" (for a TinyOS 1 application you would select "1"). If the "SF Baudrate" field is None then the "SF Version" is ignored. Finally, make sure you select the same "Channel" as the one for the Oscilloscope application. Your configuration should now look like the one shown the next figure:

To actually program the images on the nodes scroll down, press the "Install" button and wait. After not much longer than 1 minute you should see a page with the "Execution log". Check for possible errors (any line "Could not find symbol [...] ignoring symbol" is only telling you that the respective symbol was not found/changed in the application image) and scroll down to the bottom where you can find a summary of the "Install" operation. Here you can also see that a SerialForwarder has been started for node 13:

To forward SF e.g. for node 13 use: ssh -nNxTL 9013:localhost:9013 twistextern@www.twist.tu-berlin.de

In the next section we will establish an ssh tunnel to the TWIST server and connect to the SerialForwarder of the BaseStation node. The remainder of this section summarizes the fields and options for controlling an active job over the web interface.

The following table describes the fields in the "Job configuration" section:

Field	Meaning
Node list	Whitespace separated list of node IDs on which the image will be programmed
Image	The image to be programmed on the nodes in the "Node list"
SF Baudrate	Whether a SerialForwarder is started for each of the nodes in "Node list" and what baudrate it will use
SF version	The version of the SerialForwarder: use 1 for TinyOS 1.x and 2 for TinyOS 2.x
Channel	The CC2420 radio channel

The following table describes the buttons on the bottom of the "Controlling active job" page:

Button	Meaning
Install	Installs the image(s) on the node(s) specified in the above "Job Configuration" section; SerialForwarders will be started (if selected) and nodes are powered on
Erase	Programs the TinyOS Null application on the selected set of nodes
Reset	Resets (powers off & on) the selected set of nodes
Power On	Cuts the USB power supply for the selected nodes
Power Off	Enables the USB power supply for the selected nodes
Start SF	Starts a SerialForwarder for the selected nodes
Stop SF	Stops the SerialForwarder for the selected nodes
Start Tracing	Stores the serial data output from the nodes in a trace file
Stop Tracing	Stops storing data in a trace file

By pressing the "Start Tracing" button the serial data output from all nodes are automatically stored to a trace file. This file can be accessed via the job control page by pressing the "Traces" button (with your job checked). If you want to use automatic tracing then it is recommended that during install you select the correct "SF Baudrate" and "SF Version". After the install process, you can then simply click on "Start Tracing" without having to manually start the serial forwards.

Exchanging Data via the Serial Connection

Through the previously described "Install" operation a SerialForwarder for the BaseStation node was started. In order for your tinyos-2.x/apps/Oscilloscope/java/Oscilloscope.java client to connect to this SerialForwarder, you first need to establish an SSH Tunnel to forward the port of the SerialForwarder to your machine. At the very end of the execution log you find the syntax for this SSH command (type it into a shell):

ssh -nNxTL 9013:localhost:9013 twistextern@www.twist.tu-berlin.de

Once you have forwarded the port you can access the remote SerialForwarder like a local one. However, when you start your client application make sure that it attaches to the correct port as specified in the SSH Tunnel (the above command forwards the remote port to your local port 9013). For example, to start the JAVA Oscilloscope client you would first need to set the MOTECOM environment variable as follows:

export MOTECOM=sf@localhost:9013

Now you can start the Oscilloscope GUI by typing:

.\run

in the tinyos-2.x/apps/Oscilloscope/java directory as described in TinyOS 2 tutorial 5.

You should now see an Oscilloscope GUI like the one described in the TinyOS tutorial.

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TWIST_job_management.png	104.83 KB
TWIST_active_job_control.png	89.52 KB
TWIST_example_job_control.png	61.46 KB