MEMS Studio CSV export - Documentation for new_data bitmask field?

[hareee234]

Hello,

I'm using MEMS Studio to log data from a multi-sensor glasses platform for biomarker extraction research. My sensor configuration includes:

• ST1VAFE6AX (Accelerometer @ 240 Hz, Gyroscope @ 240 Hz, vAFE enabled)
• LIS2MDL (Magnetometer)
• LPS22DF (Pressure)
• STTS22H (Temperature)

The CSV export includes a new_data column containing hex values (e.g., 0x08, 0x10, 0x18, 0x20, 0x400). I understand this is a bitmask indicating which sensor(s) have new data in each row, but I cannot find official documentation for the bit assignments.

Through empirical analysis (checking which sensor columns actually change when each bit is set), I determined:

Bit Mask Sensor Correlation

Bit 3	0x08	Accelerometer	96.6%
Bit 4	0x10	Gyroscope	96.6%
Bit 5	0x20	Magnetometer	99.9%
Bit 6	0x40	Pressure	—
Bit 10	0x400	vAFE	—

Questions:

1. Is there official documentation for the new_data bitmask format in MEMS Studio CSV exports?
2. Are these bit assignments consistent across different sensor configurations, or are they dynamically assigned based on which sensors are enabled?
3. Is filtering rows by this bitmask the recommended approach for extracting clean, single-sensor data streams at their true ODR?

Thank you for any guidance! 

[Miroslav BATEK · Accepted solution]

Hello @hareee234 

your observation is correct, here is complete list of bits for new_data flag:

Accelerometer	0x008
Gyroscope	0x010
Magnetometer	0x020
Pressure Sensor	0x001
Temperature Sensor	0x002
Humidity Sensor	0x004
Interrupt	0x040
MLC	0x080
FSM	0x100
ISPU	0x200
VAFE/QVAR	0x400
Accelerometer HG	0x800

We are going to add it in the next version of MEMS Studio user manual.

The bit assignment remains consistent across different sensor configurations.
Yes, filtering rows by this bitmask is the recommended approach for extracting clean, single-sensor data streams at their true ODR.
If you use DatalogExtended firmware you can also specify single sensor as Datalog period source, it means only new data from this sensor will create new line in the log file.

[hareee234]

Hello,

Thank you for the comprehensive bitmask mapping, seems like it works well. I've been able to extract as follows. 

Verified bitmasks:
- Accelerometer (0x008): ✓ 240.7 Hz, 75,827 samples
- Gyroscope (0x010): ✓ 240.7 Hz, 75,827 samples
- Magnetometer (0x020): ✓ 10.4 Hz, 3,261 samples
- Pressure (0x001): ✓ 1.0 Hz, 311 samples
- Temperature (0x002): ✓ 1.0 Hz, 315 samples
- vAFE/QVAR (0x400): ✓ 120.4 Hz, 37,913 samples
Seems like this would work well for our use case.