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L3GD20 Temperature issue

Steven Burck
Associate III
Posted on November 26, 2015 at 10:49

Hello,

I'm integrating an L3GD20 gyro into a device, to replace a different gyro.  For X, Y and Z, everything is fine, but the temperature is not.

If you look at the attached jpeg picture, this is a graph from when the device was tested in the test oven.  The red and blue lines are the temperature readings of the old gyro (red line) and the secondary CPU (a 8051 based RF controller, blue line).  Both of these lines more or less track what the oven was doing during the test.  The L3GD20 seems to be running backwards.  However, on the datasheet it reads ''Temperature data (1LSB/deg - 8-bit resolution). The value is expressed as two'scomplement.''  

I did some searching for this on the internet, and found a couple of Arduino sites which discussed similar behavior, but with no solution.

The reading is being done by SPI done by an FPGA.  The read is an 8 byte read starting at the temperature address, and going through the Z angle (0x26-0x2D).  As I stated, the angles are fine.

Any suggestions?

#gyro #temperature-sensor
1 REPLY 1
louda.marian
Senior
Posted on July 14, 2016 at 16:41

Hello,

the temperature value from sensor is OK.

In datasheets is reported that:  Temperature sensor output change vs. temperature is -1 °C/digit and the value is reported as two's complement. But there is no base value. According to my calculations the real value is ''50 - OUT_TEMP).

Best Regards,

Marian