Matt

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Matt
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  • @Segotia I did not recognize the android syntax initially. limit(1) is invoking a firmware downsampling filter on the data source. As called it allows one sample to pass per 1ms, so signals with sampling rates greater than 1kHz will be reduced to…
  • @Lomsor a number of factors went into the decision but MMS is based on nRF52840. The design should work with nRF52833 as far as I can tell but the first build is on nRF52840.
  • Hi @Segotia Let me try to answer all your questions. * 100Hz is the typical sampling rate fed into sensor fusion, which represents 10ms sample to sample. The sensor fusion itself may appear as a low pass element to orientation change. * BLE…
  • @Timo_at_Myontec the low frequency clock on MMR is 250ppm typical, 500ppm worst case. It is trimmed against the high frequency crystal, and retrimmed if the temperature changes more than 2 degrees. This only applies if you are using the logging syst…
    in Clock stability Comment by Matt March 19
  • @kustra Very interesting theory about the magnetometer auto calibration. Let me shed some light on how the calibration endpoints in the MetaWear API work. Same as in the BNO, the calibration profile cannot be loaded into the sensor fusion proc…
  • @robgorbet * The fix for this issue is in firmware, and will be available for all units as an over the air update. * It will be easily resettable by API, and very likely automatic in existing code -- a stop/start cycle will do it.
  • @robgorbet @alexdpoon @fryjs The expected behavior is for the reference frame to reset when the sensor fusion library is internally reset -- this occurs when starting/stopping sensor fusion, or when changing mode settings. However, as seen in you…
  • @py1 the present firmware implementation does not allow the frequency to be adjusted. It is set to operate at 400kHz.
    in I2C clock Comment by Matt November 2020
  • @kustra MblMwCalibrationData.mag is equivalent to bno055_mag_offset_t with a calibration accuracy indicator appended to it. It represents a hard iron offset in xyz with a scaling radius. The units on radius are not indicated. Byte 9/10 contains a va…
  • @TimC there is a high pass filter built into the device which does precisely that. It performs a low pass identical to the filter you are using, and subtracts it from the input to produce the output. In the C++ API it is named mbl_mw_dataprocessor_h…
  • @mgeorgi we are posting the revision 2 schematic on the documentation page. The datasheet specs did not change from revision 1. The only change was replacing a battery charge management IC that went EOL. It has the same pin map and behavior as revis…
  • @kustra we will look into this as a possibility for future firmware releases.
  • @kustra as presently implemented the API does not allow this. Presently it requests the full log length, and then starts a readout of that full length. The firmware and API protocol protects against lost data when the connection is interrupted, how…
  • @kustra the ultimate decision is made either in iOS or in the BLE controller in the phone. There is a limit to the total available bandwidth for all connected devices, and they must be scheduled within time slots to achieve the desired connection pa…
  • @worsterk you can use a gpio input on the MMR, and the pin change event system in the API to log the pulse event. MMR pins are only 3V tolerant, so you will need to level shift the pulse signal first -- with a voltage divider, zener circuit, active …
  • @kustra we confirmed this part of the API did not change with the latest MetaBase. The function you linked should never recurse -- your MetaMotion device running firmware r1.5.0 must also be running bootloader revision r0.4.0. The dependency check …
  • @Lomsor I have no concrete answer at this time. Note that with the introduction of nRF52833 there is an available SoC which supports both 5.1 direction finding and USB so it has recently become a possibility.
  • @zhatiayua please update your firmware to latest and let us know if the issue persists. I would also make sure that your application is clearing the log before starting a new logging session. It may be that your devices contain data from older ses…
  • @FraSabba The APIs expose powerful raw configuration options for the sensors, and in this case you may have unintentionally set a mode that interferes with normal operation. If your only goal is to change the advertising interval, I would recomme…
  • @carltonguc I would have to see a circuit to fully understand what you are describing and whether there are further hazards beyond those described by @Laura . Note that the haptic module always applies a duty cycle and this may interfere with your s…
  • @horang2 which example are you working from? The C++ API only manages the MetaWear device protocol, the connection itself must be established using BLE hooks on the platform you are working with. The parameters for setting up the connection provide …
  • @zhatiayua thank you for your comments and data. We are aware of this issue and testing for the root cause.
  • @u0078867 yes, this technique is most similar to RBS as described. Retrieving the sensor clock value requires a BLE write and notify cycle which adds additional uncertainty to the clock synchronization.
  • @kustra Firmware 1.5.0 updates the bluetooth firmware stack in order to support BLE 5.1, which required a new bootloader (r0.4.0). MMR r0.4 devices ship with bootloader r0.3.3, so the update should need to search so far down the dependency list. T…
  • 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…
  • @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…
  • @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.
  • @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…
  • @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…
  • @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.