The Sun God has been frowning on humanity for quite some time now as we continue
to make little use of his gift that keeps giving—solar energy. But EnOcean
Inc. gives him a reason to smile with its EVA120C wireless sensor kit, which
relies on the company's STM110C solar-powered transmitter module (see
the figure). Its small solar cell offers an integrated energy store for
unrestricted functionality that lasts 60 hours in total darkness.
Using several of the kits, developers
can construct a continuously adaptable
wireless sensor network (WSN). A WSN
built with STM110Cs can be used collaboratively to monitor temperature, gas,
humidity, vapor, current, light levels,
water, pressure, location, occupancy, and
other parameters. WSN applications
include environmental monitoring, home
automation, and healthcare.
With the kit, engineers also can simulate performance, get results, and develop
application-specific WSNs. It includes several data inputs, such as three 8-bit
analog-to-digital converters and four digital inputs for detecting several types
of conditions. To facilitate communication between multiple receivers, each
kit includes a low-power radio transceiver with a 9-cm (868 MHz) or 24-cm (315
MHz) whip antenna.
Designers can set the kit's configurable wakeup signal via jumpers to
alert the system every second or every
10 or 100 seconds. Upon wakeup, each
unit broadcasts a telegram that includes
its unique sensor ID, input data, and
checksum. The computer monitoring the
data from the radio nodes then would
be able to detect any significant
changes in input values compared to
the last transmission.
In addition to the interval wakeup setting, the unit may be woken using a pair of
pins. Any change in wakeup pin status will
instantaneously wake the unit up. At that
time, the unit will transmit all analog and
digital inputs regardless of any change (or
lack thereof) in the values.
The kit offers a transmission range of up to 300 m at a power of 10 mW. It
can hit 125 kbits/s using amplitude-shift keying (ASK) modulation. Measuring
0.8 by 1.6 by 0.4 in., it includes RS232 and USB interfaces, a Microchip microcontroller,
a low-power sleep timer, potentiometers to simulate analog inputs, an LED display
to verify successful telegram transmission, and a threshold detector. The kit
may be purchased for $530.
EnOcean Inc.
www.enocean.com
