Read gyro/accelerometer data with lower sampling rate

pradeepvr · November 2016

Is there a way to read gyro and accelerometer sensor data every few seconds (for instance every 2 or 3 or 4 seconds) ? Below are the only possible values which is not of use for me.

enum OutputDataRate {
    ODR_25_HZ,
    ODR_50_HZ,
    ODR_100_HZ,
    ODR_200_HZ,
    ODR_400_HZ,
    ODR_800_HZ,
    ODR_1600_HZ,
    ODR_3200_HZ;

  }

propan · November 2016

Set ODR to minimum and add the Time processor before stream.

bmi160GyroModule.routeData()
        .fromAxes()
        .process(new Time(Time.OutputMode.ABSOLUTE, 2000))
        .stream("gyro_stream").commit()

pradeepvr · November 2016

Hi @propan, thanks for the help. The above code is not fetching data every 2 seconds, I am getting data every 50 milliseconds. Below is my code snippet.

try {
    final Bmi160Gyro gyroModule = mwBoard.getModule(Bmi160Gyro.class);
    final Logging loggingModule = mwBoard.getModule(Logging.class);
    if (mySwitch.isChecked()) {
        if (!gyroSetup) {
            gyroModule.routeData().fromAxes().stream("gyroAxisSub")
                    .commit().onComplete(new CompletionHandler<RouteManager>() {
                @Override
                public void success(RouteManager result) {
                    result.subscribe("gyroAxisSub", new RouteManager.MessageHandler() {
                        @Override
                        public void process(Message msg) {
                            final CartesianFloat spinData = msg.getData(CartesianFloat.class);
                            Log.i("test", spinData.toString());
                            ((TextView) findViewById(R.id.textView7)).setText(spinData.toString() + Units.DEGS_PER_SEC);
                        }
                    });
                }
            });
            gyroModule.routeData().fromYAxis().log("gyroAxisLogger").commit()
                    .onComplete(new CompletionHandler<RouteManager>() {
                        @Override
                        public void success(RouteManager result) {
                            result.setLogMessageHandler("gyroAxisLogger", new RouteManager.MessageHandler() {
                                @Override
                                public void process(Message msg) {
                                    final float ySpinData = msg.getData(Float.class);
                                    Log.i("!test", String.format("Log Gyro: %.3f", ySpinData));
                                }
                            });

                            loggingModule.startLogging();


                            gyroModule.configure().setOutputDataRate(Bmi160Gyro.OutputDataRate.ODR_25_HZ)
                                    .setFullScaleRange(Bmi160Gyro.FullScaleRange.FSR_250);
                            gyroModule.routeData()
                                    .fromAxes()
                                    .process(new Time(Time.OutputMode.ABSOLUTE, 2000))
                                    .stream("gyro_stream").commit();

                            gyroModule.start();
                        }
                    });
            gyroSetup = true;
        } else {
            loggingModule.startLogging();
            gyroModule.configure().setOutputDataRate(Bmi160Gyro.OutputDataRate.ODR_25_HZ)
                    .setFullScaleRange(Bmi160Gyro.FullScaleRange.FSR_125)
                    .commit();
            gyroModule.start();
        }
    } else {
        loggingModule.stopLogging();
        gyroModule.stop();
    }
} catch (UnsupportedModuleException e) {
    Toast.makeText(this, e.getLocalizedMessage(), Toast.LENGTH_LONG).show();
}

propan · November 2016

pradeepvr
You need to add the filter before the stream or logging that you are using. It will pass the data further every 2 seconds. Check in the API docs how filters are working.

in your case put it before .stream("gyroAxisSub")

and .log("gyroAxisLogger")

.process(new Time(Time.OutputMode.ABSOLUTE, 2000))

Read gyro/accelerometer data with lower sampling rate

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