Title: Wireless Sensor Node: monitoring low-rate phenomena using a low-power RF-enabled microcontroller
Abstract: A low-power wireless enabled sensor module built from commercial off-the-shelf components (COTS) is presented. This sensor/transmitter module is the basic component of a low cost telemetry system that can monitor low time-constant phenomena, such as temperature and humidity in our implementation, in which energy preservation is a target specification. The heart of the module is an RFPIC microcontroller (MCU) with a RF-UHF transmitter from Microchip. The module is normally kept in sleep mode to decrease energy consumption; in this condition, it uses 1.5 muW (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sleep</sub> <0.5 muA @ 3 V). The module is woken up by a low frequency (125 kHz) magnetic field pulse that is sensed by a tuned LC tank in the module that drives a low power comparator (MAX919) whose output wakes the MCU up from sleep. When it is woken up, the module takes the intended measurements, uses a current of I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> =450 muA for tens of ms, and then it transmits the results to a central receiver using a common-use RF ISM band (434 MHz) and then goes back to sleep. Each burst of transmission lasts =30 ms and uses a current of I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TX</sub> =5 mA in this condition, which depends on the output power configuration.
Publication Year: 2007
Publication Date: 2007-10-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 4
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