Matt

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Matt
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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…
  • @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…
  • 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
  • @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…
  • 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…
  • 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…
  • @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…
  • @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…
  • 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…
  • 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…
  • @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 …
  • 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…
  • @ebadier Thanks for your comments. We are looking at adding either a dedicated stop command, allowing repeated calls to refresh the timer, or accepting 0ms duration as a parameter to turn off an active output. All of which would be able to meet yo…
  • Hi fryjs, The MetaMotion devices run the library version of bosch sensorfusion from the BNO055. AXIS_MAP_CONFIG is, unfortunately, not a native feature of the library. It could be possible to add axis remapping to the native sensor outputs in…
  • Hi Blake, You're right, the MS5803 interface is a bit unconventional. The write (command) sequence is identical, except that they are interpreting the register address as a command. If you pass the command byte into mbl_mw_i2c_write as the re…
  • @lyubente, there is no voltage regulator on MetaMotionC, the battery directly supplies 3V. The radio SoC has a built in DC/DC converter for energy efficiency.
  • Hello Abdel, The maximum continuous discharge rate for the battery is 1C, which translates to about 110 mA. Higher current draw is not recommended due to self heating. The battery protection (PCM) circuit will cut off the battery around 2 to 5 …
  • That's great! We'll take a look at how we can clarify the documentation.
  • Hi Daryl, The I2C transactions look correct for the address byte. One key thing about I2C is that the address is only 7 bits, and the 8th bit is the R/Wb bit. Because the command was a write command the 8th bit is 0, which is why it seems lik…
  • Hi @Manos. Is that the complete wiring diagram? If so, you should attach the ground from the power source to one of the MetaWear ground connections as well. You can route the wire from the ground connection at the pressure sensor -- this is pre…
  • @MichaelG Thank you for reporting your findings. Idle current consumption is specified at nominal operating conditions (25C). This is standard for electronic component specification. We will update the data sheet to be more clear. My 30-50% co…
  • Piezo elements generate very high voltages when subject to mechanical impulses -- as much as several kilo volts. A high voltage spike like this on a pin will definitely reset a MetaWearC, if it does not destroy the pin circuitry, the chip or both.…
  • I wanted to note this as well from the SK6812 datasheet, this is the only spec they have for brightness: Could the doubled green intensity be working as expected?  Do you have a reference point for how "pure white" should look -- presumably usi…
  • @jdlombardo Lets focus on fast mode because slow is invalid for these new type pixel strands. Regarding fast mode and reduced brightness, this should imply that the "1" code is an issue for the pixels to receive. In your "pure white" test,…
  • @jdlombardo That is odd.  RG r0.5 could not generate as precise of signal for the fast mode due to its clock rate, though it would have been in spec to its original target (fast mode ws2811).  The slight change in timings on the SK6812 may have ma…
  • @jdlombardo Those neopixels should be used on fast mode (800kHz).  It looks like the latest driver chips do not have a slow mode at all anymore, so their normal is always our "fast". Our timings were based on WS2811 slow and fast modes.  Fast …
  • @MichaelG There is a firmware release in final testing that resolves the idle current issue. Root cause was silicon errata on the SoC, where the timer used to generate PWM signals does not correctly shut off when it is stopped.  The new firmwa…
  • @JanWeber Could you confirm that the drift in this data sample is in the pitch data and not the yaw data? These is not any obvious change in data when the drift begins.  It is very clear that the noise is 3-4x+ higher in magnitude than any vis…
  • @StefaanAvonds We have discussed possibly adding an encryption interface in the future that may behave similarly, but it is not under development or on our present roadmap. Something we can possibly do in the near term is add a "Connected" eve…
  • @rajmishra You can attach that between a GPIO and the 3V or regulated 3V pin, but you will need to add a series resistor to limit current.  GPIOs should not exceed 5mA. You can use the GPIO module as well as the timer module to create a simple…