I was driving along minding my business the other day when all of a sudden I noticed that my 'Check Engine' light had come on. Nothing seemed to be wrong with the car, but unfortunately the only way to diagnose the problem was to take the car in to be serviced. After a few moments (much to my chagrin!) the serviceman informed me that I had not closed my gas cap all the way, and that was the reason the light had turned on! I was embarrassed and wished that instead of flashing the check
engine light there had been some user interface telling me what the problem was. That way I would not have had to go all the way to the dealer to be told I did not screw the gas cap down all the way.
There are many situations where the need for a user interface is not only helpful, but necessary. It is this
capability that Research Associate, Leo Selavo, and others in the Department of Computer Science at the University of Virginia are developing for the Mote platform. The SeeMote is an in-situ visualization and logging device for wireless sensor networks. This device addresses three challenges that are present when building and analyzing wireless sensor networks - 1) the need for an in-situ user interface, 2) a data logger and 3) a power consumption meter. You might think that this capability is already available in laptops, PDAs, flash memory chips, etc... but for wireless sensor networks where size, battery life and cost are crucial, another solution is necessary.
Enter the SeeMote - a compact, lightweight, low power and low cost multi-modal sensor module. The SeeMote, which is designed to work with Crossbow's popular MICAz Mote platform addresses these challenges by providing 1) a graphical user interface component that combines a color liquid crystal display (LCD) and 5-way buttons, 2) a power meter component that is reconfigurable for attaching various low-power devices and 3) a data logger component that is interfaced to a removable secure digital (SD) or multimedia memory card (MMC). The SeeMote provides a solution for certain wireless sensor networks that are difficult to reach, wearable or large-scale. Often, a sensor network can be observed in the field via a laptop or PDA which is accessed through a gateway device, however, these devices have limited power supply when mobile. Sometimes, large amounts of data must be logged in the field because transmitting them over the network may take too much time and bandwidth or cost too much power. Therefore, the SeeMote's compact portable power measurement device is a valuable tool for measurements in the field.
The SeeMote offers several application functionalities:
1 - Pocket Frequency Analyzer
Radio communication can suffer from interference from other electronic devices. The frequency analyzer on the SeeMote can monitor existing electronic devices within the environment and determine which channel is least affected by the interference and configure the new devices to use these channels.
2 - Removable Storage
The module provides interface for SD and MMC data storage cards. The removable storage media enables customization of the memory size according to the application as an alternative way to transport stored data between the Mote and the data processing computer.
3 - In-Situ/ Remote Sensory Data Display
The LCD module enables the Mote platforms to be capable of immediate sensory data display while in the field. The application receives data over the radio and plots them on the LCD screen. Instead of using the built in LEDs on the MICAz to display variable values, the SeeMote display enables the user to monitor the actual data and use it for debugging, gathering current ADC readings and quick data queries.
4 - Power-meter functionality
The module is also capable of measuring electric power consumption by monitoring electric current and supply voltage for external low power devices which allow it to diagnose power consumption on the LCD and log it in the removable storage.
This development by the researchers at University of Virginia enables a set of applications for WSN diagnostics, configuration and debugging in the deployed network's field setting. The SeeMote provides wireless sensor networks something that the check engine light in my car does not - the ability to see the issue right then and there. Till the interface on my car becomes more sophisticated, I now make sure to twist my gas cap a few extra times to avoid such a silly service call!
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