LIS2DW12: FIFO-Threshold-Interrupt Jitters at 1.6kHz

[Loris Wyss]

Hello ST-Community!

When I'm using the LIS2DW12 at ODR=1.6kHz, the Interrupt for reaching the FIFO-Threshold is jittering with 1/ODR, but only if the threshold is greater than 12. If it's less or equal, everything is working fine.

The buffer-Mode is set to FIFO-Mode, but this behaviour also occurs in Continous-Mode.

The Power-Mode is set to High-Performance/Low-Noise.

The Interrupt is routed to the INT1-Pin

The two images show the rising edge on the pin INT1. The time between the two cursors "a" and "b" is 624us (almost 625us), which would equal to 1/ODR (1/1600 = 625E-6)

As written, this only happens if ODR is set to 1.6kHz and the FIFO-Threshold is greater than 12.

Does anyone have some further informations regarding this issue?

Thanks in advance for your answers!

Greetings,

Loris

[Loris Wyss]

Hi @Eleon BORLINI​ , thanks for your answer.

Ok, so here is a step-by-step instruction to reproduce the jitter on the PCB I sent you:

1. Supply the Board with +24V
2. Flash the software I sent (STM32F4.bin) you on the MCU
3. Connect the probe of the Oscilloscope to INT2
4. Trigger the Oscilloscope on rising Edge at INT2
5. When Triggering at Edge n, then Edge n+1 has a jitter of ca. 625us

If it didn't work, please try to flash software with the free Keil uVision Evaluation version (Available here: https://www.keil.com/demo/eval/arm.htm)

When you follow these instructions step by step, the issue should occur.

Could you please check, if that works for you?

I will check, if my issue is related to the one described in the other thread.

Thanks and regards

Loris

[Loris Wyss]

Hi @Eleon BORLINI​ 

Can you give me an update about this issue?

I still don't know if you were able to reproduce this behaviour on the HW I sent you...?

Regards

Loris

[Eleon BORLINI]

Hi Loris, you are fully tight... it is a subject that grieves me because Milan and Italy in general is in lock down since two months and the lab activity is only partially ongoing. So, to recap, basically I tested the devices in stand-alone mode (HW involved: STEVAL-MKI109V3 + STEVAL-MKI179V1) and didn't find any issue, but I didn't perform test with your platform :( I would like to make up for lost time as soon as the lockdown is over. Regards

[Loris Wyss]

Hi @Eleon BORLINI​ 

I hope you're doing well!

Have you been able to return to the lab?

Can you give me a time frame in which I can expect some test results from you?

We've basically got an entire Project on hold right now due to this issue.

Thanks and Regards

Loris

[Eleon BORLINI]

Hello @Loris Wyss​ , you are fully right and I'm here in lab to try to test the board, but the USB connector seems damaged (maybe due to the soldering of the GND wire), so I cannot plug the USB easily.

Since in these days I'm pretty alone in lab, what I can suggest you is to ask for support to the ST regional sales offices/representatives and FAE. I may send them your PCB, if you open your OLS request. Regards

[Loris Wyss]

Hello @Eleon BORLINI​ 

Thanks alot for your answer!

Well, the USB-Port isn't needed to put the Board in operation, it's only for Logging/Debug Purposes.

The PCB is powered through the GND/+24V-Pins.

Regarding your suggestion for further Support:

-I'd like to get a confirmation from you that the issue is present before taking any further steps.

Thanks and Regards, Loris

[Eleon BORLINI]

Hi @Loris Wyss​ , but how to:

2. Flash the software I sent (STM32F4.bin) you on the MCU

without USB port?

Regards

[Loris Wyss]

I'm sorry, this was some unclear information from my side.

The MCU is flashed over the small black socket with ten pins and the SWDIO-Interface.

If you don't have such a progammer, you can also try it without re-programming it; I flashed the software I sent you before shipping the PCB, so the Firmware should be the same.

Regards, Loris

[Loris Wyss]

Hi @Eleon BORLINI​ 

I hope you're still doing well.

Have you got any news for me? Have you been able to reproduce the jitter or atleast put the pcb in operation?

If not, can you guarantee that I will get some results from you until the end of next week (10th of July '20)?

Else I would open an OLS request to get support on this issue.

Thanks and Regards,

Loris

[Eleon BORLINI]

Hi @Loris Wyss​ , tomorrow I'll be in lab with some time for this test, and I'll update you in any case by this week with the results I'll get. In case these outputs will not be conclusive, as you say it will be better to contact the OLS. Regards