The device is composed of two main parts: one connects to the Internet via an Ethernet connection; the other includes one or more wireless display units.

• Connecting to the Internet, checking for new emails
  
  The central unit connects to the network automatically (via DHCP) and regularly checks the number of email messages in the specific mailbox (via POP3 protocol) at specific intervals. Thanks to the integrated web server, the email address, access to the account and the frequency of checking for new messages can be modified using a web browser.
  
  The unit has a modular structure composed of an Ethernet and a 2.4 GHz radio frequency module.

• Displaying the number of emails, motion detector
  
  The handheld, portable part of the device maintains a wireless connection with the central unit. One central unit may connect to multiple such portable devices.
  
  The number of new emails is displayed in two digits. When a new email message arrives, the current value is displayed for a few second and then, to minimise energy use, the display turns off again. When the device is moved, the display turns on again. To reset the counter, shake the device.
  
  Thanks to the ultra low consumption level of the radio system, the battery powered device requires recharging only after an extended period.

Webalert is designed to inform the user about events accessible via the Internet even when the user’s computer is turned off.

Such events may include changes in stock exchange rates, the number of visitors to the blog, weather information, the number of emails, etc., or any other more complex or application based event may be monitored and the value of the change displayed.

There are several display options, including blinking LEDs, displaying digits or longer texts and even engine powered mechanical motion.

Webalert is a tiny and extremely energy-efficient device.

Adam Dunkel’s UIP Ethernet stack was used when programming the device.

The PHY layer needed for radio communications was created using ATMEL open source libraries; we programmed the MAC layer ourselves and plan to publish these codes as open source software. The MAC layer is currently not Zigbee compatible.