sensor

I'm new for this technology, can somebody help me to know about some doubt? Q-1. What is the size of CoAP packet? (I know there is 4 byte fixed header, but what is the maximum size limit including header, option and payload?) Q-2. Is there any concept for Keep Alive like MQTT? (It works on UDP for how much time it keeps open the connection, is there any default time or it keeps open every time when we send packet?) Q-3. Can we use CoAP with TCP? (Main problem with it CoAP is it works on UDP, is there any concept like MQTT QoS? Let's say a sensor publishes some data every one second, if

So I'm looking for a way to get the current value of the Light Sensor (in Lux obviously) on a button press. Here is the code I'm using to implement control of the light sensor public class SensorActivity extends Activity implements SensorEventListener { private final SensorManager mSensorManager; private final Sensor mLight; int minLux = 0; int currentLux = 0; int maxLux; public SensorActivity() { mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mLight = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); } protected void onResume() { super.onResume(); mSensorManager

I am using Raspberry pi3 and DHT11 sensor for temperature monitoring project. I have following pin positions VCC to pin no : 2 Ground to pin no : 6 Output to GPIO : BCM22 i.e pin no 15 Code that I have used: public class WeatherStationActivity extends Activity { private Handler mHandler = new Handler(); private TextView mTxtStatus; private PeripheralManagerService service = new PeripheralManagerService(); private Gpio tempGpio; private int i = 0; int[] dht11_dat = {0, 0, 0, 0, 0}; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.d("Weather

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center . My question is very simple and straight forward. Is there any technique through which i can calculate the heartbeat of a person using android device. I googled it and found some results in which they implemented it using camera. Any other idea or help will be highly appreciated. Thanks. I suppose in order to measure heartbeat you

I want that my View rotates only in landscape mode, clockwise and counterclockwise. I read about the only counterclockwise for android < 2.2 and that's not a problem, my App will be +2.2 for now. I modify my manifest to catch Configuration Changes android:configChanges="keyboardHidden|orientation" I override my activity to catch Configuration Changes @Override public void onConfigurationChanged(Configuration newConfig) { and I know how to catch orientation Display display = ((WindowManager) getSystemService(WINDOW_SERVICE)).getDefaultDisplay(); int rot = display.getRotation(); but... I don't

I'm trying to read temperature data from a DHT11 temperature sensor, using pi4j. I followed the code written in c and python in this site: http://www.uugear.com/portfolio/dht11-h ... or-module/ But it's not working. when I test the instruction 'dht11Pin.getState()' it's always in HIGH state, never changing. Is there anything wrong in my code? Below is my code: import java.util.concurrent.TimeUnit; import org.apache.logging.log4j.LogManager; import org.apache.logging.log4j.Logger; import com.pi4j.component.ObserveableComponentBase; import com.pi4j.io.gpio.GpioController; import com.pi4j.io.gpio