Sponsored By
Efika 5200B Project
Solar-powered Efika measuring temperature and humidity using Embedded Linuxin category Embedded
proposed by a-tsuji on 1st January 2008 (accepted on 1st January 2008)
Project Summary
AbstractThe objective of the project is to develop the ubiquitous ecology computer which works with solar power. Ubiquitous means that everyone can use computer anytime, anywhere. The greatest feature of the Efika is to be used an embedded processor though having a function of general PC. This shows that is the big difference from other products such as laptop/notebook PC, industrial embedded computer, etc., therefore the Efika has much possibility to be able to use in various situation.In general, the feature of an embedded processor is low power consumption, good stability,long life, and fixed function for special purpose. I have focused on these points and generality of the Efika that is able to give much improvement to many conventional products.
Data Acquisition System
I am developing the data acquisition system as one of the application of this project. The data acquisition system is used to capture natural phenomenon as digital data. Many of stand-alone data acquisition system have only a fixed function for data capture and some ports to interface the PC.
Project Blog Entries
Although the project was accepted a couple of weeks ago, I have already finished building the solar-powered Efika. Now, I set up the web server on the solar-powered Efika and am measuring the temperature and humidity of the room by using it. In this blog, therefore, I will write about the details of the project what I have done.
Solar-powered Efika:
Actually, I have never seen the small-scale solar-powered PC. If it is realized, it provides us extending the possibility of solar-powered embedded systems. The Efika features of interest is very low power consumption, around 6 W at the operation without monitor. It is sufficient power consumption in order to realize the solar-powered system. I planned to build the measurement equipment with small-scale photovoltaics which is portable, self-powered, and can be used anywhere. Since the Efika can be used as a PC, it means to be able to perform complicated processing easily, which is difficult to be constructed by general microcontroller that has only several I/Os and A/Ds. The measurement equipment is just one example of solar-powered Efika, there might be other applications that dramatically improve the efficiency in our eco-life.
Figure 1 shows a block diagram of the solar-powered Efika. The major parts of the system are;
- Solar battery (12V, 1.5A)
- Battery charge controller
- Analog meter (optional)
- Efika
- Keyboard, Monitor (for debug)
Figure 1 A block diagram of the solar-powered Efika
Observe the temperature and humidity that is obtained from sensors connected the Efika such as SHT-11 (high precision humidity and temperature), DS1621 (temperature), DS1307 (real time clock), and MAX1236 (A/D converter) devices controlled by the Efika through the USB port. The Efika is powered by photovoltaic cells for portability.
I am using libusb to control the I2C-Bus line, SDA and SCL. Controlling the I2C-Bus device is really simple and is able to get the various information though the almost same way.
The test server for the realtime observation, only temperature and humidity, is available at http://earth.is.tokushima-u.ac.jp/rrd.cgi
These graphs on the server are automatically generated and updated every minute by the RRDtool that is famous for the network traffic monitoring.
I am now writing the technical report for a large technical conference in March 2008.