9 months ago.

About temperature sensor into LSM9DS1

/media/uploads/ereponin/img_20190312_175751.jpg Hey. Thermometer readings have an average deviation of 3 to 5 degrees. I compared the readings with a Polder thermometer and a thermocouple connected to ADAM-4118. The thermometer is attached to the chip on the hot melt. Heat transfer should be sufficient.

When heating and cooling the chip lsm9ds1 readings were underestimated from 3 to 5 degrees. Pay attention to this. I tried the IMU mbed library, two libraries from Adafruit and Sparkfun for Arduino, and three different chips from two different batches. I2C interface. Also tried to read the thermometer registers on the line 0x15 and 0x16.

The Celsius temperature value from the registers I counted like this: T=((RegHi (0x16) << 8) | RegLo (0x15)) / 16 +25. The result was no different from the library.

Has anyone else noticed this error?

PS: I tried with a voltage of 2.2 V, 2.4 V, 2.8 V and 3.3 V. The thermometer readings did not change even at different supply voltages. I fed the entire chip from one to the yarn without separating the VDD and VDDIO as well as made by the manufacturers of the debug boards Adafruit and SparkFun. /media/uploads/ereponin/sensors_schem.png /media/uploads/ereponin/2019-03-13_19-03-05.png

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1 Answer

9 months ago.

The device is calibrated for Vdd @ 2.2volts see page 14/72:

https://www.st.com/resource/en/datasheet/DM00103319.pdf

Check you have a separate well decoupled Vdd supply @ 2.2volts to the module, something like one of these regulators:

https://eu.mouser.com/ProductDetail/Texas-Instruments/TLV70022DDCR?qs=sGAEpiMZZMsGz1a6aV8DcKqTQjvDUH%252Bf8jzlDY52YrI%3D

Welcome. Thank you for your answer. I tried with a voltage of 2.2 V, 2.4 V, 2.8 V and 3.3 V. the thermometer Readings did not change even at different supply voltages. I fed the entire chip from one to the yarn without separating the VDD and VDDIO as well as made by the manufacturers of the debug boards Adafruit and SparkFun.

posted by Evgeniy Grafek3d 13 Mar 2019

The data sheet does not appear to indicate temperature accuracy, perhaps its just not that accurate and is just used to add some temperature compensation to the IMU functions.

posted by Paul Staron 13 Mar 2019