USER MANUAL
STM 550X / EMSIX
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ENOCEAN MULTI-SENSOR
© 2020 EnOcean | www.enocean.com F-710-017, V1.0
STM 550x / EMSIx User Manual | v1.0 | February 2020 | Page 22/79
3
Sensor functionality
STM 550x integrates a set of sensors used to measure environmental parameters. The fol-
lowing chapters described their characteristics in detail.
3.1
Light level sensor
STM 550x integrates a dedicated light level sensor with narrow aperture and a spectral re-
sponse o
ptimized to mimic the human eye’s perception of ambient light.
This light sensor
reports the light level directly underneath the sensor (spot measurement).
Figure 11 shows the spectrum response of the STM 550x illumination sensor compared to
that of the human eye.
Figure 11
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Spectrum response of the light level sensor
3.2
Solar cell
In addition to the light sensor, STM 550x provides the option to use the calibrated solar cell
response to report wide area illumination. This can be used both as input for lighting con-
trol systems (e.g. to report ambient light for daylighting applications) and to verify the
available light level is sufficient for self-powered operation of STM 550x.