USER MANUAL
STM 550 / EMSI
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ENOCEAN MULTISENSOR FOR IOT APPLICATIONS
© 2020 EnOcean | www.enocean.com F-710-017, V1.0
STM 550 / EMSI User Manual | v1.3 | September 2020 | Page 24/97
3.5.1
Wake on acceleration
If acceleration exceeding the configured threshold is detected for the first time after a period
without exceeding this threshold then STM 550 wakes up immediately (wake on acceleration
event).
Wake-on acceleration can be used to immediately trigger the transmission of a message
when an item is moved or starts to vibrate. The threshold for the wake on acceleration feature
is adjustable as described below.
3.5.2
Acceleration sensor parameters
The acceleration sensor integrated in STM 550 allows configuring the following parameters:
◼
Full-scale magnitude
The full-scale magnitude determines the maximum acceleration magnitude that will
be reported. Higher settings allow reporting higher magnitudes but will result in less
resolution and thereby less sensitivity. The default measurement of +-2g should be
sufficient for most use cases.
◼
Acceleration threshold
The acceleration threshold determines the threshold of acceleration vector change
required to trigger a wake-on vibration event as described above or to reduce the
transmission interval as described in chapter 2.3.6.
Setting a lower acceleration threshold results in a higher sensitivity to acceleration
vector changes. STM 550 uses by default the minimum possible threshold corre-
sponding to 1/64 of its full-scale magnitude.
◼
Sampling rate
The sampling rate determines how often the acceleration vector will be measured.
Higher sampling rates allow detecting shorter vibrations but require more energy to
do so. Higher sampling rates should only be used if minor vibrations are not de-
tected when using the minimum acceleration threshold.
Table 2 below shows the supported configuration options for each of these parameters and
their default settings in STM 550.
Parameter
Supported Options (bold = default)
Full-scale magnitude
+-2g
, +-4g, +-8g, +-16g
Acceleration threshold
1/64
… 63/64 of full scale
Sampling rate
1.6 Hz,
12.5 Hz
, 25 Hz, 50 Hz
Measurement resolution
10 bit for each (x, y, z) direction
Table 2
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Acceleration sensor parameters