MLX90614 Infrared Thermometer

The Falcon, Eagle, SensorNode LoRaWAN, and SensorData LoRaWAN support the MLX90614 Infrared temperature sensor (single pixel I2C sensor). For the complete list see Supported Sensors and Inputs

For information on this sensor, visit: https://www.melexis.com/en/product/MLX90614/Digital-Plug-Play-Infrared-Thermometer-TO-Can 

DM devices which have integrated this sensor simply read and report the raw value (with some averaging) returned by the sensor. There is a conversion which must be done to convert this value into the temperature. Details are on page 30 of the Melexis datasheet.

It is also important to note that this sensor reports both Ta (ambient temperature) and To (object temperature). Users should make sure not to confuse the two.  


Set Up

Wiring

Connect to 3V3, SCL, SDA and GND as per the Sensor's datasheet. 


Parameters

On the Eagle and Falcon, simply select the MLX90614 as a task item - see Falcon & Eagle Cellular - Configuring Task Schedules:

Additionally there is a parameter tab to configure the analogues which the readings are reported in, and sample. 


Averaging

The output of the sensor can at times be very 'spiky' so some averaging is built in via the Number of Samples parameter. Each time the sensor records a measurement, it will take n samples, 50ms apart, average them, and report this average value. 

For example, if your Task Period was set to 5 min, and number of sample set to 5, every 5 minutes the device will wake up, take 5 readings from the sensor (over 250ms) and upload the average of these 5 values. 

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