We are using a BME280 in an electronics housing and I wanted to see if there is any declaration available for dual-use of the item. That is a declaration confirming if it has both civilian and military applications.

Look forward to the reply.

Many thanks,

Will

For documentation issues and code examples I would know how oversampling is defined in detail.

I understood that no oversampling means no measurement.
But what means
oversampling_x1...x16
Thats not really clear, because in theory oversampling refers to Nyquist Theorem.

If we use oversampling greater than x1 are there done kind of meanvalue calulation?

In other words, I would like to use one 2.2uF capacitor bank (consisting of many smaller value capacitors and a plane to keep ESL and ESR down) for multiple sensors. The idea here is that we would make sure that the BMM350_INIT function, which to my knowledge triggers the reset function on the chip, was run one at a time for sensors that share a common CRST bank to avoid having multiple chips charging / discharging the bank at the same time.

When starting DD software I choose this firmware: Bosch_Shuttle3_BHI360.fw

Magnetometer / readout is not displayed, also magnetometer is not in list of physical sensors.
Chip (U4) seems to be on the board. Tried bith I2C and SPI communication.
What is my problem? Thank you for hints.

Regards Martin

We need to calibrate the CO2 using 0ppm CO2 air. The calibration air also has very low VOC but has a controlled humidity of 50% and temperature of 21degC. We were not intending to calibrate the BME690 in this set up.

Before the unit is place in the chamber, we get reasonable IAQ readings from the BME690 and we get a reported accuracy of 3 from the BSEC library. After several hours in the chamber, the unit is removed and put back in normal air. Even after a couple of hours, the IAQ index does not return (even close) to the previous readings. The unit runs on an internal battery and is continuously powered throughout this process.

My question is - is it possible that the BSEC runs another calibration while in zero air which gives an unusual result and therefore gives quite different readings when returned to "normal" air?

Do you have a method of "calibrating" the IAQ index after this zero air process?

Current firmware flow:

1. MCU wakes from deep sleep (timer, 600 s).

2. We call bsec_init / bsec.begin() as a fresh BSEC instance (we currently do not call bsec_set_state on wake).

3. We load the 33v_300s_28d config and subscribe at ULP.

4. We put the BME690 into parallel / autonomous heater profile (bsec_sensor_control → parallel mode).

5. We drain the parallel FIFO and pass those samples into bsec_do_steps.

6.Timestamps passed into BSEC are derived from MCU millis(), which starts at 0 after every deep sleep. FIFO samples in one wake are timestamped only a few milliseconds apart (heater-step spacing), not 300 s apart.

7. We read IAQ / eCO2 / accuracy from that wake, then the MCU goes back to deep sleep.

8. The BME690 is left in parallel mode during MCU sleep (we do not put the sensor into BME69X sleep).

9. BSEC state is saved to NVS only when IAQ accuracy increases; it is not restored on the next wake.

We previously also tried restoring BSEC state across sleep and putting the sensor to sleep between cycles. IAQ / eCO2 were still very high at accuracy 3.

example output temparature: 29.6 °C Humidity: 47.6 %RH Pressure: 984.2 hPa IAQ: 196 IAQ accuracy: 3 eCO2: 7333 ppm T/H/P look plausible. IAQ ~200 and eCO2 ~7000 ppm do not: we would expect IAQ near 50 and eCO2 in a few hundred ppm in that room, not 7k.

What are we doing wrong?

I am currently evaluating the BMA400 using an ESP32 and would like some guidance on implementing a battery-optimized configuration using the sensor's built-in tap detection and interrupt functionality.

The required functionality is:

• Single-tap detection

• Double-tap detection

• Hardware interrupt output

• Low-power operation for battery-powered applications

• Automatic transition between low-power and normal operation, if appropriate

• Minimum practical current consumption while maintaining reliable tap/double-tap detection

I understand that the BMA400 low-power mode operates at a fixed 25 Hz ODR and has a typical current consumption of approximately 0.8 µA in the referenced configuration, while normal operation has a higher current consumption of approximately 3.5 µA, depending on the configuration.

I am considering an operating sequence similar to:

Low-power mode → wake-up → normal mode → tap/double-tap detection → interrupt → return to low-power mode

I would like to confirm whether this is the recommended approach.

Specifically:

1. Can the BMA400 use low-power mode for activity monitoring and then switch to normal mode for reliable single-tap/double-tap detection?

2. What ODR and filter configuration is recommended for the BMA400 tap engine?

3. Is there a recommended configuration sequence for combining:

   • Auto-wakeup

   • Single tap

   • Double tap

   • Interrupt

   • Auto-low-power

4. When the device wakes from low-power mode, can the previously configured normal-mode settings be restored automatically, or does the host need to reconfigure the sensor?

5. What current consumption should I expect for this type of operating sequence, rather than only the standalone low-power-mode current?

6. Are there any important restrictions or interactions between low-power mode, auto-wakeup, and tap/double-tap detection that should be considered?

7. For the interrupt output, what configuration is recommended for reliable single-tap and double-tap detection?

I am also looking at the Zephyr RTOS BMA4xx driver, which already recognizes the BMA400. I would like to understand whether this existing driver can be extended to support the required BMA400 tap/double-tap functionality, or whether Bosch recommends using a different driver/API approach.

For initial evaluation, I am using an ESP32 with an I²C connection to the BMA400 and can provide non-confidential register configurations, measurements, or test results if required.

I cannot share proprietary application details or company-specific code because of confidentiality requirements.

Thank you for your guidance.

which BOSCH Sensortec sensor is capable of measuring the ambient pressure in a pure helium gas environment without deteriorating in quality? Is it only the BMP280?

Many thanks and my best regards