LoRa IoT Smart Room Sensor User Guide
T0006338_UG
Version 1.5
TEKTELIC Communications Inc.
Page 18 of 30
1
𝑇
= 𝐴 + 𝐵 ln (
𝑅
𝑅
0
) + 𝐶 ln
2
(
𝑅
𝑅
0
) + 𝐷 ln
3
(
𝑅
𝑅
0
)
where
𝑅
0
is the reference resistance, in
k
Ω, of the thermistor
(e.g. 10
k
Ω), and where
R
is the thermistor resistance at temperature
T
, which can be obtained as
𝑅 =
68.1 × 𝑉
1800 − 𝑉
where
V
is the reported voltage from the sensor in mV.
Coefficients A, B, C, D are usually given by the thermistor manufacturer. If not given, the
coefficients can be determined by measuring 4 voltage-temperature pairs from the
thermistor, and forming 4 linear equations with 4 unknowns (i.e. A, B, C, D).
The physical connector and its mating connector of the External Connector are listed in Table
1-4. The Room Sensor is not supplied with an external connection jumper cable. The link in
Table 1-4 is a suggested cable. It is the customer's responsibility to modify the cable harness for
their application.
Should an external cable be connected to the External Connector, the external cable MUST be
routed through a cable clip, characterized in Section 2.6, and the cable length MUST NOT
exceed 3 meters. See Section 2.6 for the connector pin assignment and cable installation.
Table 1-4: Smart Room Sensor Interface Connector Types
Interface
Sensor Connector
Mating Jumper Cable (300mm)
External Connector
JST B2B-ZR(LF)(SN)
1.3.7
Moisture Detection Transducer
The Room Sensor Base model contains a Moisture Detector. The Moisture Detection
Transducer is built into the bottom surface of the Base model housing (screw side). The
transducer senses changes in capacitance at the bottom surface of the Sensor housing in the
presence of moisture. In other words, the moisture is detected at 0 mm range from the bottom
surface (the bottom surface should get moist). This transducer is best suited to sensing the
presence of water. The transducer is sensitive materials in the sensing region so the trigger set
point for reporting the presence of water must be calibrated for each application. This
transducer can also be used to sense liquids other than water or skin. The customer must
evaluate each application and configure the trigger point as required.
A calibration command can be sent to the Sensor to set a "dry" condition. The alarm point can
also be set directly as a value. Sample period for moisture detection can be set to one of 4
