TDDI07 Distributed embedded software and networks Department of Computer and Information Science Lab 1 – Introduction to TinyOS and nesC
Learning objectives
The main objective of this lab is to make the student familiar with the
development environment for sensor platforms using TinyOS and understand the
basic concepts of its programming language nesC.
Specifically, after completing the lab the student shall be able to:
•
•
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Explain the component and interface concept and how to wire them in
order to create an application.
Understand the concurrency model of TinyOS being familiarised with the
concepts atomic, commands and events.
Program a simple application to run in a real hardware sensor node.
Assignment 1: Blink the led
You are requested to complete the application skeleton BlinkTask in order to
make blink a led on the sensor node. The led has to be 1 second switched on and
9 seconds off.
First, you will find out the needed components and interfaces for the application
and wire them together. Information about the interfaces and components can be
found in the TinyOS directory (/opt/tinyos-2.1.1/tos).
You will use only one timer to control the delays. The timer should be fired only
when it is time for the led to change. Finally, compile and test your solution in the
sensor node.
Assignment 2: Sensing application
You are requested to complete the application skeleton PhotoMeter. The
application has to measure the illuminance using a sensor and display the result
on the leds. For that purpose, the application has to sample data every 50
milliseconds from the sensor (PhotoC component in the skeleton) and display the
value in the leds according to the following rule: values in range 0-33% out of the
maximum will turn the led0 on, 33-66% will turn the led1 on and values greater
than 66% will turn on the led2. Only one led should be on in each interval. The
maximum will be 1024 (RANGE in the skeleton). You will store 10 values in a
circular buffer and display the average of the last 10 values.
Led0 – 0-33%
Led1 – 33-66%
Led2 – 66-100%
Read interface:
The illuminance data is provided by the Read interface in 16 bits. Printf can help
you to debug the sensor readings if needed (see additional resources). Study the
read interface in the TinyOS directory and write code for handling its event. When
the reading is successful, store the data and use a separate task to process it.
TDDI07 Distributed embedded software and networks Department of Computer and Information Science Circular buffer:
You are required to use a circular buffer implemented as an array in order to
store the data readings. This circular buffer will be used in the data processing
task and therefore you have to synchronise the access to the variables.
Data processing:
The calculations and manipulations of the leds should not be performed within
any event handler. Performing heavy calculations in an event handler means
further events occurring during the calculations will be blocked/delayed/lost. This
decreases the responsiveness and accuracy of the system.
Therefore, you are required to use a separate task to process the data as it is
provided in the skeleton (processData). If any data is available in the buffer it will
perform the display function, where the calculations and manipulations of the leds
have to be done. You will display the average of the 10 last values in the leds.
Optional: the sample values have to be converted to illuminance (Lux). For that
you need to use the following formula:
!"#$%&
∗ 1.5
4096
!""#$%&'&() = 0.625 ∗ 10! ∗
100
Data collection:
You are required to show the value that you display in the leds in the terminal
using the printf() function. You can show the average or a single sample. The
printf() function buffers the data and it does not write the data until its buffer is
more than half full. You can use printfflush() after calling printf() to directly send
the data.
In order to display the values in a graph, you will need to redirect the output of
the PrintfClient program to a file and plot it using the LiveGraph application (see
resources). Your application should only output the value in order to plot it later.
The output can be redirected with the following command:
java net.tinyos.tools.PrintfClient > yourfile.csv
Once you have downloaded LiveGraph, run it (right click and open it with the java
runtime) and choose your comma separated values (CSV) file as data input.
Other sensors:
You can use the SensirionSht11c component to collect temperature or humidity data. The SensirionSht11c component provides the Temperature and Humidity
interfaces that can be read using the Read interface, as you have done before for
the illuminance. Plot the temperature and humidity data in the virtual machine
using LiveGraph.
The temperature sample needs to be converted to temperature (Celsius) using
the following formula:
!!"#!"#$%"! = −39.60 + 0.01 ∗ !"#$%&#$'"
TDDI07 Distributed embedded software and networks Department of Computer and Information Science The humidity sample needs to be converted to relative humidity (%) using the
temperature as in the following formula:
ℎ!"#$#%& = −2.0468 + 0.0367 ∗ !"#$%& − 1.5955 ∗ 10!! ∗ !"#$%&
!"#$%&'"()*&+&%, = !"#$"%&!'%" − 25 ∗ 0.01 + 0.00008 ∗ ℎ!"#$#%& + ℎ!"#$#%&
To hand in:
Once the lab is finished, the student has to show the application running in the
sensor nodes to the lab assistant.
After showing the application, the student must send a zip file containing a
written report answering correctly to the lab preparatory questions and the final
source code of the applications. You also have to explain in brief how your
applications work (booting process, sequence of events…).
The e-mail must contain the string “TDDI07 Lab X Group Y” where X is the lab
number in the subject name and Y is the group number.
Additional resources for this lab:
TinyOS programming:
http://www.tinyos.net/tinyos-2.x/doc/pdf/tinyos-programming.pdf
TinyOS tutorials:
http://docs.tinyos.net/tinywiki/index.php/TinyOS_Tutorials
TinyOS printf:
http://docs.tinyos.net/tinywiki/index.php/The_TinyOS_printf_Library
LiveGraph:
http://www.live-graph.org/
http://downloads.sourceforge.net/live-graph/LiveGraph.2.0.beta01.Complete.zip