What does the DEN_A/G pin on the LSM9DS1 actually do?

[evan2]

Posted on February 10, 2015 at 15:24

The title really says it all.

The pin description for the LSM9DS1 says that the DEN_A/G pin is the Accelerometer/Gyroscope Data Enable. This sounds important, but I can't see anywhere in the datasheet that explains what you're meant to do with it. Can I just tie it to 3.3V, since I want data to always be enabled? Or tie it to ground? Or maybe to the CS_A/G pin, so that it only takes readings when I'm not actually communicating with it? The only thing I can't do is connect it to a microcontroller pin, because I've run out of those. Thanks for any help #data-enable #lsm9ds1 #den_a/g

[oyvind2]

Posted on March 05, 2015 at 16:27

Bump. Wondering about the same thing. Very strange that this is not explained in the datasheet.

[lukas239955_stm1_stmicro_com]

Posted on August 21, 2015 at 12:29

Hi Slatye,

I am wandering the same. Does anyone has an experience with it? I left it floating. I can communicate with the device. The problem is that the acceleration values are still the same and do not change with any configuration I try. Could it be related with DEN_A/G issue? Thank you.

[johnlowen9]

Posted on December 18, 2015 at 20:31

I am wondering the same. The datasheet leaves a lot to be desired. Many pins/functions are left without explanation as if we somehow should know this stuff.The descriptions are very terse and for someone new to the chips, it is a very steep learning curve.

[harri]

Posted on August 05, 2016 at 14:27

My guess is that the chip outputs magnetometer data by default, and this line selects accel/gyro data output.

[Petr S · Accepted solution]

Posted on August 08, 2016 at 14:29

Hello all,

DEN functionality:It is possible to perform an external trigger synchronization/stamp using three different modes: level, impulse or edge sensitive trigger. 1) DEN Level Sensitive (LVLen bit configuration):It is performed a stamp action: the Least significant bit (LSB) of the Gyroscope data output is equal to DEN pin value, it is used to correlate data with an external signal.2) DEN Impulse Sensitive (IMPen bit configuration):As the previous, but it is possible to stamp (Gyroscope LSB) using short impulses (also < 1/ODR)3) DEN Edge Sensitive (EXTRen bit configuration):The stamp action is not performed, but it is used to reduce the ODR to DEN frequency, and at the same time, it is possible to fill in FIFO and Output Register only the sample acquired after “DENâ€� rising edge.DEN Register Configuration address 11h, 3 MSB of 11h Register are <Edge_Sens_EN, Level_Sens_EN_, Level2_Sens_EN>

DEN Configurations Table

BIT_7

BIT_6

BIT_5

Edge_Sens_EN

Level_Sens_EN

Level2_Sens_EN

DEN FUNCTION

1

0

0

Edge Sensitive

0

1

0

Level Sensitive

0

1

1

Pulse Sensitive

Best regards,

Petr

[cbertrand]

Posted on September 08, 2016 at 12:05

Hi Petr and all,

I read your answer but on LSM9DS1 relative to this topic, I didn't found anywhere the configuration bits you talk about in register 11h.?! In fact, i'm stuck in my project with LSM9DS1 that deliver things like constant values for accelero, gyro and magneto. The DEN_A/G pin is left open in my design and I suspect that point. Thanks for your help. Cyrille

[Petr S]

Posted on September 16, 2016 at 14:12

Hello all,

1. Please try to explicitly set these 3 mentioned bits of the CTRL_REG2_G (11h) to 0 even if the description in datasheet says it's 0 as default.2. Please specify if the constant data you get for all 3 sensors at least make sense. For example: does the accelero constant data really look like accelero data, even if it's still the same all the time? Or does it look more like gyro or magneto data? Same question for gyro and magneto...Best regards,Petr

[michaelmichael9138]

Posted on July 05, 2017 at 02:52

Hi Petr,

Thanks very much for the information.

But I wonder how ST even published a datasheet with a pin with zero documentation. 

And then ST has failed to add the above information for over a year.

Every single time I consider ST parts I run into documentation issues.

David

[Thierry.B]

Hi all,

Does anyone have any more information about this pin DEN_A/G ?

Thanks.