Matt
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A brief elaboration on these answers: Accelerometer, Gyroscope and Magnetometer are calibrated by the sensor supplier and internally compensated (in the raw data). Pressure and humidity sensors contain supplier provided compensation coefficien…
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@gschu the ADC is setup in 10 bit mode for compatibility with older models, but capable of 12 bit. Its capable of 200k samples per second, but actual throughput will be limited by the API/interface methods used for triggering reads. For the best per…
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@nekos BLE 5.1 direction finding and long range are not supported on our existing products due to the chips they are based on. MMR and MMC use nRF52832. BLE5.1 offers channel selection algorithm #2 and 2MHz bandwidth.
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@force I would be surprised if the magnetometer is causing any issue. The linear acceleration will be derived almost entirely from the accelerometer. Integrating to get velocity will tend to always have drift issues because it is summing error and o…
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@Force MetaBase will use NDoF for linear acceleration on an MMC. Are you integrating the vector magnitude of linear acceleration or one axis in particular? I assume the sharp dips are the turns. Is it possible for your velocity model to apply some c…
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@danielj pairing and bonding are not supported by our devices. Apps are able to connect and re-connect in the background, and are identifiable by ID.
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@sd104400, the lowest native sampling rate of the accelerometer is 0.78125 Hz, which is slightly less than 1 per second. It is possible to use the data processing system to average or further down sample the sensor output. Matt
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The logging system records entries using the internal device clock. At the start of log readout, the present state of the device clock is tagged against real world (smartphone) time. As they are read out, the relative time (as recorded internally) …
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@FooTheBar are you logging or streaming?
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@Force, what does your raw data look like after filtering? The turn may be too rapid and violent for the sensor fusion to accurately track through it. Dead reckoning is a notoriously difficult problem without an absolute position sensor (such …
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@IBo, you'll want to have a look at the datasheet for the board model you're working with to determine axis orientation. Rotation is also indicated and follows the right hand rule. The sensorfusion implementation defines euler rotation as x=pitch, y…
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@FooTheBar, I am surprised that you would be seeing clock drift over such a short interval of time. Were both data captures from the same session? The clock uncertainty between two devices will be different after starting and stopping a recording. …
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@fryjs, that certainly seems a reception challenge more than throughput. Our antenna is resilient to detuning from proximity to body parts, but at the wrong angles too much energy will be absorbed. I'm not certain what I can comment publicly on hard…
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@ivoc The MetaWear firmware and APIs already have a fully implemented and featured driver for the BMI160. You should not ever need to access it via the SPI interface. If your goal is to work with the BMI160 you should absolutely use the APIs. …
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@fryjs the ble5 firmware is still under development. Unfortunately, the long range extensions require new hardware, and cannot be enabled by firmware update. Its possible if your reliability issue is throughput related, that the higher throughput (2…
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@NIVO The process of putting a device to sleep is fairly complex in firmware, I would be quite surprised if the devices are entering that exact state. Note also that on the MMR model, attaching the 5v source would also be a trigger to wake the d…
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@kustra Note that the haptic module will be present on any board with the drive circuitry, regardless of whether or not a motor is attached -- it is not an indication of the presence of a motor. We will run some additional firmware tests on th…
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@zozo If you log, all data from one specific metawear device will have 0.2ms resolution and a base clock source accurate to approximately 250ppm. Multiple sensors on one metawear device will be logged against the same time base with that resolut…
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@zozo If you're using the logger, the resolution on the clock is approximately 200us. When reading out and synchronizing with the smartphone, the uncertainty in the data transmission comes into play -- this is on the order of 40 ms for iOS and 20…
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@Camille assuming the ECG kit has sufficient amplification and buffering you should be able to read the signal through the analog GPIO APIs. It is possible to do some on board processing using the data processing API, such as filtering or peak detec…
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Hi @PabloBurgos IMU_PLUS would be the best sensor mode for this application. However, the starting orientation will be relative to gravity. It should be straightforward to calculate rotation relative to the starting value. Matt
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@kustra Approximately 2048 is the saturation value of the magnetometer (the z has more compensation and is a slightly different sensor than x/y). This means a fixed magnet is exerting a field that exceeds the measurement range of the sensor. As a…
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Hi @jonteberg, What process are you using to calibrate the sensor fusion? When starting and stopping the sensor fusion subsystem, the calibration will be lost if it is not explicitly read out and loaded in. Could you share some raw magnetomete…
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Hi @kustra, thank you for your detailed report. The process you describe looks sufficient for readout and loading of calibration data. Can you confirm that during calibration, the sensor was put into a variety of physical orientations for cali…
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@kustra You have the general process down. You will want to perform step 4 before step 3, disabling sensor fusion will drop the internal state and will not be guaranteed give the correct results. Step 6 can be done at any time, and you will…
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@gjin, the data rate is driven by an oscillator internal to the accelerometer and meets +/-1%. There may be a slight additional error or offset introduced when synchronizing the time base of the sensor with that of the smartphone. Is the result repe…
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Hi @zacdy, We generally recommend using thermistors because a thermocouple generally requires a precision amplifier. There is firmware built in support for NXRT15XH103FA1B, otherwise you can use the ADC for raw voltage to use any thermistor yo…
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MMRUser, If you look at the raw x-y data from your sensor in motion, it is producing perfect sine waves 90 degrees out of phase. This is the expected result. The basic yaw calculation is incorrect because there is both an x and y zero offset. Th…
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@goamberg If you have a chance, I would highly recommend trying to calibrate a sensor or pair of sensors before a logging session. The calibration has the most effect on the magnetometer data, and calibration is automatic within sensor fusion. If …
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Hello Leonard, None of the MMR series devices are specified to work without the battery connected. The only officially supported configuration includes the battery. This applies to all firmware versions. The issue is that the battery charge m…