Automode, logger seems to log but not enough data in the SD card

[anthonyADV]

Hi,

I'm using the STEVAL-STWINKT1B and the automode to log data, with the FPSNSDATALOG2 firmware. I'm reaching out because, although the logger seems to run for multiple hours, I only get a few minutes (or at best a couple of hours) of data saved on the SD card.

Here’s what I did:

• I charged the dev kit's battery for about 7 hours. Before logging, the ST BLE Sensor app showed the battery level at 95%.

• I formatted the SD card to FAT32 with a 32K allocation size.

• I copied the following device_config.json to the root of the SD card:

  • nof_acquisition = 0

  • logging_period_s = 900 (15 minutes per file)

• I started the logger by pressing PWR and RESET. The green LED blinked at 4Hz, indicating logging had started.

I monitored the logger as much as possible. After 8 hours, the green LED was still blinking, and the ST BLE Sensor app showed:

Alarm: Logging ongoing
Battery: 55%
(see screenshot below)

However, when I checked the SD card, I only found about 2.5 hours of data, specifically, 10 folders of 15 minutes each. But I expected at least 8 hours of logging.

So my question is: Why do I only get a few hours of logged data, even though the logger appears to be active (green LED blinking) for much longer?

Additional notes:

• I repeated this test several times, and the result is always the same: much less data on the SD card than expected.

• Here's the battery level over time during the abovementionned test:

  • 0h: 95%

  • 5h: 65%

  • 5h15: 61%

  • 6h: 60%

  • 6h30: 58%

  • 7h46: 55%

• I’m still using the SanDisk Extreme 256GB SD card (SDSQXAV-256G-GN6MA). I’m aware this is not one of the cards officially tested with the STEVAL-STWINKT1B, alas, I haven’t been able to get a different one yet.

Thanks in advance for your help !

Best regards,
Anthony

[anthonyADV]

Hey, just a quick follow-up, I still haven’t found a solution. Thanks in advance

[SimonePradolini]

Hello @anthonyADV 

Sorry for the late reply. I'm launching a 24-hours test session and come back to you soon.

Best regards,

Simone

[SimonePradolini]

Hello @anthonyADV 

I tested different SD cards and power supply setups. I can't find any issue while using an external power supply or a power bank via USB. Instead, I got your same undesired behavior with a couple of SD cards with the board battery-powered.

While acquiring data on the SD card, the firmware checks for the battery status: if it detects something not working properly (battery discharge, low battery percentage, ...), it saves data and closes the acquisition. This is a safety procedure that we implemented to avoid broken data acquisition due to a power supply failing.

My suspect is that there’s an issue in the battery status check: I'm debugging there, wishing providing you with a solution soon.

Thanks for your feedback on our products. I really appreciate your job

Best regards,

Simone

[anthonyADV]

Hi @SimonePradolini,

Got it, I’ll wait to hear back from you :) I’ll keep going with my recordings using a power supply setup.
Can I ask which power bank and/or external power supply you used for your tests? Mine tends to shut down unexpectedly, so I’ll probably get the same as yours to make sure I don’t run into issues.

Thanks a lot for your replies!

Best,
Anthony

[SimonePradolini]

Hello @anthonyADV 

I'm using a generic one, a USB power supply from a smartphone. Are you still in trouble? Do you have the same undesired result also by reducing sensors ODRs or by disabling some of them? For example: what if disabling IMP23ABSU and IIS3DWB at all?

Best regards

Simone