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 7/97
1
General description
This user manual describes the functionality of the STM 550 EnOcean multisensor module, of
the STM 550 Installation Kit and the EMSI Easyfit Multisensor in the following frequency
variants:
◼
STM 550, STM 550 KIT and EMSIA using 868.3 MHz radio (main market Europe)
◼
STM 550U, STM 550U KIT and EMSIU using 902.875 MHz radio (main market US)
◼
STM 550J, STM 550J KIT and EMSIJ using 928.35 MHz radio (main market Japan)
T
he term “STM 550” is used t
hroughout this user manual to describe all variants unless
otherwise noted.
1.1
Basic functionality
STM 550 is a flexible self-powered multisensor module family capable of measuring temper-
ature, humidity, illumination, magnet contact status and acceleration. It enables the realiza-
tion of energy harvesting wireless sensors for light, building or industrial control systems
communicating using the EnOcean radio standard.
STM 550 uses the same mechanical form factor as the industry standard PTM 21x modules
from EnOcean.
STM 550 implements the following sensors:
◼
Temperature
◼
Humidity
◼
Illumination
◼
Acceleration
◼
Magnet contact
STM 550 will report periodically (by default approximately every 60 seconds, configurable via
NFC) the latest measurements of these sensors. In addition, STM 550 can also report its
internal energy level and the amount of light available at the solar cell.
STM 550 will report immediately if the status (open / closed) of the magnet contact changes
or if a change in acceleration measured by the acceleration sensor exceeds a user-defined
threshold for the first time.
Radio telegrams transmitted by STM 550 can be encrypted and authenticated using AES-128
security based on a device-unique private key and a sequence counter in accordance to the
EnOcean Alliance Security Specification. This ensures integrity, confidentiality and authentic-
ity of the transmitted telegrams and prevents telegram replay (retransmission of previously
transmitted telegrams).
STM 550 is self-supplied via an integrated solar cell which generates the energy required for
its operation. For cases where ambient light is not sufficiently available, STM 550 provides
the option to mount a CR1632 backup battery.