Archive for the ‘My research project’ Category

Seeeduinoboot v0.2

The version 0.2 of the Seeeduinoboot is now available …

The new version add some new updates:

  •    the XBee module is waked up, to be sure that it is not sleeping, before sending a confirmation response back (ZigBee Transmit Request);
  •   the _record type_ byte from the telegram has been eliminated;
  •   the _payload id_ field from the telegram has been increased from 1 byte to 2 bytes.

The new telegram format, which should be received by the bootloader application:
|| start byte    ||  length || frame type || 64bit sender address || 16 bit sender address || options ||  payload id || start address || record type || data || checksum ||
|| 1 byte (0x7E) || 2 bytes || 1 byte     || 8 bytes              || 2 bytes              || 1 byte  || 2 byte || 2 bytes || 1 byte || n bytes || 1 byte ||

During the tests it was observed that setting on XBee module a longer time before going to sleep will decrease significant the time necessary for firmware application update procedure to completes.

Link to Google code page:

Categories: My research project

Reading more precisly the temperature using a thermistor

November 30, 2011 Leave a comment

A thermistor is a resistor whose resistance modifies as the temperature modifies. Sometimes the variation is linear, but usually it is not. Since there is specified, into the thermistor datasheet, a table with values (correspondences between resistance and real temperature value) it is possible to make, in the most simple way, a linear approximation between 2 set of values. This type of approximation is ok but not really good when the precision is a very important thing.

We started to make some simple tests using a thermistor provided by Seeeduino (in the last time I become a fan of them 😀 ).

It is small in size and it could be easily inserted into the walls (of course, using some drilled holes) or placed on different surfaces (attachable with a glued band). The datasheet is attached bellow. The values are also available in CSV format: link (provided by Eric McKinley).

Using Matlab we have done the representation of the characteristic in 2 different ways: linear interpolation and spline interpolation. The spline interpolation should be much closer to real characteristic.

Into the figure below it is quite hard to distinguish the difference between them, but a zoom will reveal more details.

Anyway the difference between the 2 types of interpolation  is small enough. And if we do the difference between them we get the next result. For normal values of the temperature (normal, for an office space) the maximum difference is approximated to 0.01 degree Celsius, a value which could be neglected at office spaces monitoring. For other monitoring applications it could be important.

Into an Arduino application it would be complicated to make the spline interpolation when it is necessary to compute the temperature. The simplest way is to do the linear interpolation, or a more sophisticated way is to have an equation which to represent the spline interpolation.

To determine the equation we have 2 ways:

  1. using the Steinhart-Hart equation format. A specific electrical circuit could be used to determine the equation. I just took the coeficients specified by Richard on Seeeduino website, and they are just fine (a=1.114482E-3, b=2.373524E-4, c=6.895445E-8). The coefficients values are correct only for this type of thermistor. For more correctness each independent thermistor should be tested separately, since the characteristic could differ slightly from one device to another.
  2. determine a logarithmic equation using Matlab environment (polyfit and polyval methods). The equation is more complex but is more simply to determine it if we have available the characteristic of the thermistor. For the Seeeduino thermistor the logarithmic polynomial equation should have the next coefficients: C4 = -0.0324,  C3 = 1.2166,  C2 = -15.4806,   C1 = 53.5809,  C0 = 127.5468  (C4 * power(log(xx), 4) + C3 * power(log(xx), 3) + C2 * power(log(xx), 2) + C1 * log(xx) + C0).

The Steinhart-Hart equation:

To select one way or the other to determine the specific equation depends on the user possibilities and if the thermistor characteristic is available or not.

To connect the thermistor presented above to Arduino board the next connection should be done.

Categories: My research project

Seeeduino Stalker v2.0 – first test

I just received my packages with the order from Singapore (Seeeduino company). I waited for it a lot. For a simple test I configure the devices as in the figure presented below.

The both XBee radio modules (series 2) have been configure with the application X-CTU and the firmware was updated to the last version. One radio device was configured as coordinator AT and one as router AT (using the same application). I succeded very easy to make a simple communication between them and after that install a simple Arduino application (which just blink a led) on the Seeeduino Stalker device.

My first impresion is that it easy to work with them and doesn’t require many knowledge about electronics (this is the advantage of having separated functionalities on modules). I will do more experiments with them these days and do more complex applications (I need more time to do this since I want also the information to be stored into a database for future processing).

I also have a good help, a book which I order some time ago: Building Wireless Sensor Networks with ZigBee, XBee, Arduino and Processing (by Robert Faludi, O’Reilly Media – could be found on Amazon at a good price).

External Research Stage in European Union, 2011

February 7, 2011 Leave a comment

My research project allow me the possiblity to go to an external University (outside Romania) where to make a part of my project  and then come back to finish it. The external research stage could take maximum of 4 months. It is a good oportunity to see in another place how the research is done and also it permits to create a collaboration between projects, change experience and maybe work together at some research papers. If you are from an University where you have laboratories on WSN, control or monitoring systems or intelligent building systems please send me a message. I will be glad to change some words with you.

Project description

Title of the project:

Contributions at the development of an intelligent area for increasing the energy efficiency in the Institute of research/development PRO-DD

Domain of research:

The technologies in the informational society


One idea of the project is to stimulate the experimental progress on the research of the wireless sensor networks (WSN) – pointing on the monitoring and control of the office/home spaces (smart office, smart home).

It will be developed a system, software and hardware, which to implement this functions. In the same time, it will be considered to integrate other functional systems, under development as research projects, dedicated for: energy management, for decreasing the energy consumption (by example: the control of photovoltaic panels, hot water panels, automatic change from one energy source to another, intelligent lightning, etc.) and for ensuring of other auxiliary functionality (by example: access control, ensuring the ambient conditions, security, etc.). All the systems considered are part or will be part of the research/development institution.

The system is based on a wireless sensor networks, which to permit the monitoring and control of the offices space or other type of rooms or external elements (equipments).

The final result is to obtain an intelligent building (smart building). All the room of the building will be monitoring using the wireless sensor nodes (hardware) and one system of software applications will permit to view the recorded information and the control of the entire system.


ACKNOWLEDGEMENT: This research project is supported by the Sectoral Operational Programme Human Resources Development (SOP HRD) financed from the European Social Fund and by the Romanian Government under the project number POSDRU/89/1.5/S/59323.

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Hello everybody!

Hello everybody on our website and thanks for encouraging the research progress. We have tried and we try to organize the website in the best way and to put useful information for our visitors. More information will appear on the website during the developing of the project and after finalizing different steps from it. Sorry if there appear English mistakes in the content of this website. We try our best.

Have a nice day!

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