Datasheet

Datasheet Evaluation Kit EK-H5
www.sensirion.com July 2015 – Version 3 3/5
Config. Alert Limits: This button is used to set the “Alert
limits”, which are reference thresholds for the ALERT
signal, available when the SHT3x is operated in periodic
data acquisition mode. The ALERT signal allows
monitoring the environmental conditions (humidity and
temperature) relative to these programmable limits.
The function of the alert feature is explained in a separate
App Note, which is available from Sensirion’s Download
Center.
Please note that the sensor handles the limit information in
a reduced data format (see App Note). The standard data
format of SHT3x-DIS has a width of 16 bits. For the limits
only the most significant bits (MSB) are used to determine
whether an alert has been met (7 bits for humidity and 9
bits for temperature). When the user inserts a limit, the
EK-H5 software automatically converts the inserted value
to the closest value matching this data format and displays
it.
When limit values are reached, the SHT3x will change the
value of the dedicated ALERT pin. Additionally, a status
register bit changes value. The “Humi. Alert” and “Temp.
Alert” cells on the main EK-H5 software screen indicate
the value of the respective status register bit (bit 11 for RH
and bit 10 for T). When the humidity and temperature
values are within the set limits (e.g. Alert OFF) the cells
are greyed-out. When the defined limit values are
exceeded (e.g. Alert ON) the cells turn red.
Configured limits can be changed during operation (after
the run button has been clicked) and are shown as red
dashed lines on the main EK-H5 software screen data
plots (see for example Figure 1).
Serial Number: The SHT2x, SHTC1 and SHT3x sensor
series provide a device specific serial number which can
be read-out via the serial interface (I
2
C). The Serial
number allows an unambiguous identification of each
individual device. It is automatically displayed on the main
EK-H5 software screen data plots in the Product Settings
section.