USER MANUAL
STM 550 / EMSI
–
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 21/97
3
Sensor functionality
STM 550 integrates a set of sensors used to measure environmental parameters. The follow-
ing chapters described their characteristics in detail.
3.1
Light level sensor
STM 550 integrates a dedicated light level sensor with narrow aperture and a spectral re-
sponse optimized
to mimic the human eye’s perception of ambient light.
This light sensor
reports the light level directly underneath the sensor (spot measurement).
Figure 8 shows the spectrum response of the STM 550 illumination sensor compared to that
of the human eye.
Figure 8
–
Spectrum response of the light level sensor
3.2
Solar cell
In addition to the light sensor, STM 550 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 550.