Hi, This question is about an application that I am using Apache Edgent, not really a development effort into Apache Edgent. But as there is no user@list I am sensding here.
I am using Apache Edgent (Java framework) to poll values from an HCSR04 ultrasonic sensor on a Raspberry Pi every 3 seconds. I use a filter to not get values from 50cm to 80cm ( https://github.com/felipegutierrez/explore-rpi/blob/master/src/main/java/org/sense/edgent/app/UltrasonicEdgentApp.java ). UltrasonicStream sensor = new UltrasonicStream(); DirectProvider dp = new DirectProvider(); Topology topology = dp.newTopology(); TStream<Double> tempReadings = topology.poll(sensor, 3, TimeUnit.SECONDS); TStream<Double> filteredReadings = tempReadings.filter(reading -> reading < 50 || reading > 80); System.out.println("filter added: tempReadings.filter(reading -> reading < 50 || reading > 80);"); filteredReadings.print(); dp.submit(topology); I want to show some message when the values are filtered. When the values do not match with my filter I can poll them, but when they match I am not returning, that is ok. However, I want just to show that a value was filtered using Apache Edgent libraries. I know that I can do something on the `public double get()` method, but I wonder if I could do this trick with some method of the Apache Edgent ( https://github.com/felipegutierrez/explore-rpi/blob/master/src/main/java/org/sense/sensor/UltrasonicStream.java ). public class UltrasonicStream implements Supplier<Double> { private static final long serialVersionUID = -6511218542753341056L; private static GpioPinDigitalOutput sensorTriggerPin; private static GpioPinDigitalInput sensorEchoPin; private static final GpioController gpio = GpioFactory.getInstance(); private double currentDistance = -1.0; /** * The HCSR04 Ultrasonic sensor is connected on the physical pin 16 and 18 which * correspond to the GPIO 04 and 05 of the WiringPi library. */ public UltrasonicStream() { // Trigger pin as OUTPUT sensorTriggerPin = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_04); // Echo pin as INPUT sensorEchoPin = gpio.provisionDigitalInputPin(RaspiPin.GPIO_05, PinPullResistance.PULL_DOWN); } /** * This is the override method of the Supplier interface from Apache Edgent */ @Override public Double get() { try { System.out.print("Distance in centimeters: "); currentDistance = getDistance(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } return currentDistance; } /** * Retrieve the distance measured by the HCSR04 Ultrasonic sensor connected on a * Raspberry Pi 3+B * * @return the distance in centimeters * @throws InterruptedException */ public double getDistance() throws InterruptedException { double distanceCM = -1; try { // Thread.sleep(2000); sensorTriggerPin.high(); // Make trigger pin HIGH Thread.sleep((long) 0.01);// Delay for 10 microseconds sensorTriggerPin.low(); // Make trigger pin LOW // Wait until the ECHO pin gets HIGH while (sensorEchoPin.isLow()) { } // Store the current time to calculate ECHO pin HIGH time. long startTime = System.nanoTime(); // Wait until the ECHO pin gets LOW while (sensorEchoPin.isHigh()) { } // Store the echo pin HIGH end time to calculate ECHO pin HIGH time. long endTime = System.nanoTime(); distanceCM = ((((endTime - startTime) / 1e3) / 2) / 29.1); // Printing out the distance in centimeters // System.out.println("Distance: " + distanceCM + " centimeters"); return distanceCM; } catch (InterruptedException e) { e.printStackTrace(); } return distanceCM; } } Thanks, Felipe *--* *-- Felipe Gutierrez* *-- skype: felipe.o.gutierrez* *--* *https://felipeogutierrez.blogspot.com <https://felipeogutierrez.blogspot.com>*
