Wireless Sensor Network project

Discussion in 'The Projects Forum' started by alexx_88, Dec 11, 2010.

  1. alexx_88

    Thread Starter New Member

    May 24, 2010

    I am currently working in developing a WSN project for my graduation thesis which is in ~7 months. My project involves designing an autonomous urban outdoor mote which can sample data every 5 minutes (or 20 during the night) from an ultrasonic range finder and send the data back to a 'root' mote which, in turn, sends the data via internet to the server.

    Long story, short, I am now concentrating on designing the sensor-mote. The mote will be powered by a 6V - 1W solar panel via a supercap. The average power consumption is 0.7 mW with a peak power consumption of ~80 mW.

    As a uC and radio solution I have gone for a chip that integrates both functionalities: ATmega128RFA1 . This IC has a 1.8V-3.3V input voltage range and the ultrasonic range finder can be powered between 3.3V - 5V.

    Ok, so I have the power consumption, I have the power generated by the solar panel, but now I am in trouble when choosing a solution for the link between this two. I have thought of 3 solutions, all of them using a supercap as the way to store the energy coming from the solar panel.

    1) Low dropout regulator: considering an input voltage between 4V - 5.5V for the regulator (to produce stable 3.3V) this has the big disadvantage of using only a part of the energy stored inside the supercap which I'll be using.

    2) Buck-boost converter : from what I saw they can use from 1V to 5.5V so this seems like the way to go right now.

    3) A low dropout regulator with two outputs: 1.8V for the uC and 3.3V for the ultrasonic range finder. This complicates things quite a bit as I have to use a level converter on the serial port linking the sensor with the uC and I don't know if the energy saved worths the extra effort and components.

    After I decide on a power solution I can calculate the capacity needed for the supercap.

    Thank you,
  2. tyblu


    Nov 29, 2010