how to understand the LIS3DH temperature reading

[satyajit2]

Posted on June 02, 2015 at 18:20

I have an application using the LIS3DH.  I need to read the values from the on chip Temperature Sensor.  I have properly setup the ADC_PD and TEMP_EN bit in the TEMP_CFG_REF (1Fh).  I'm reading the OUT_3_L (0Ch) and OUT_3_H (0Dh) at an ODR of 50 Hz.  The OUT_3_L seems to be random while OUT_3_H looks like valid data.  Three different chips measure (OUT_3_H)  as follows FA, F6 and FE.  This translates to -6, -9 and -2.  The Datasheet describes the TSDr as Temperature sensor output change vs temperature with a resolution of 1 digital/C.  So my assumption is that the translated values of -6, -9 and -2 are delta (changes) from some reference temperature (possible at MFG calibration).  The ambient temperature in the room is 23 C (~73 F).  My assumption per Datasheet was that the reference temperature is 25 C but this only correlated to the 3rd value.  Is there a reference temperature that is different in each chip? Is there a way to access this reference temperature? Possible in one of the reserved addresses?

Thank you,

#temperature-sensor #lis3dh

[Tesla DeLorean]

Posted on October 27, 2017 at 01:25

Presumably because the accuracy of the measurements is effected by temperature.

[jmjobin]

Posted on March 24, 2018 at 12:04

The problem is that it is absolutely not described as such in the datasheet and is very vague for the use of it.

I spend hours to understand why this would act in a such way, lucky that some of you guys talked about this matter.

I finally understood and see that all I was doing worked properly.

I would add that it is one of the worse datasheet I ever had to read.

Thanks guys for your help

[AKH]

For me it was showing Temperature: -253, How to consider