Matt

About

Username
Matt
Joined
Visits
313
Last Active
Roles
Member

Comments

  • @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.
  • @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
  • 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) …
  • @FooTheBar are you logging or streaming?
  • @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 …
  • @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…
  • @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. …
  • @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…
    in BLE5 Comment by Matt October 2019
  • @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. …
  • @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…
    in BLE5 Comment by Matt October 2019
  • @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…
  • @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…
  • @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…