1. Home
  2. Ezwsn: experimenting with wireless
  3. Lab 1: the development environment
  4. 1.2. oscilloscope: read the

1.1 1.2. oscilloscope: read the current consumption

<< Chapter < Page
  Ezwsn: experimenting with wireless   Page 1 / 1
Chapter >> Page >
The End Device is instructed to transmit a message every second; its radio is off the remainder of the time. Using the oscilloscope together with the 1-Ohm resistor, you will be able to visualize the current consumption of the board.
  • Leave the Access Point plugged into the computer.
  • Switch the target board on using the jumper with the 1-Ohm resistor:
    Use the 1-Ohm jumper to switch on the target board.
  • Connect the oscilloscope onto the resistor as in the following figure. What you read is the current consumption in amps of the board (U = RI, with R = 1).
    Read the current consumption of the board.
  • You should read energy consumptions close to the following Figure. There are fourmain phases: the radio is switched on (A), IDLE mode (B), RX mode (C) and TX mode (D).
    You're done when you see a screen similar to this one on your oscilloscope.
  • We can assume the boards are powered by two AAA batteries with a capacity of 1000 mA*hr, under the hypothetical condition in which the batteries hold their voltage ideally until their capacity is exhausted. The following Table can be used to calculate the approximate lifetime, using the previous measurements: Average current consumption is 0.700mA; Lifetime with a 1000mA*hr battery is about 2 months.
    Duration and average current consumption of the different phases observed.
    Phase duration av. current
    sleep 995.34ms 0.600mA
    radio is switched on 0.360ms 4.80mA
    IDLE mode 0.780ms 13.6mA
    RX mode 2.680ms 24.2mA
    TX mode 0.840ms 26.0mA
<< Chapter < Page Page > Chapter >>

Read also:

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Ezwsn: experimenting with wireless sensor networks using the ez430-rf2500. OpenStax CNX. Apr 26, 2009 Download for free at http://cnx.org/content/col10684/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Ezwsn: experimenting with wireless sensor networks using the ez430-rf2500' conversation and receive update notifications?

Ask