Java_Embedded_Open_Onli...

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1 Homework 2 - Working with GPIO and I2C Developing Java ME Embedded Applications by Using a Raspberry Pi: Homework for Lesson 2 Assumptions Team Collaboration Java_Embedded_Open_Onli... You have successfully completed the homework for lesson 1 and have set up the Raspberry Pi and your Windows PC You have a breadboard (half or full size) and the following components: A 10K ohm resistor (color code: brown, black, orange, gold) Two 560 ohm resistors (color code: green, blue, brown, gold) Two 10mm LED's (Adafruit or equivalent) Breadboard wires 26-pin ribbon cable and Adafruit cobbler or equivalent Orienting the ribbon cable on the Pi Connect the ribbon cable to the GPIO header on the Raspberry Pi so that the white stripe (pin 1) is on the right (as shown by the arrow below) Caution: Make sure that the cable is not offset before pushing it down onto the header. All pins should be covered by the cable header. Orienting the Adafruit Cobbler on the breadboard With the cobbler in the breadboard, note that Pin 1, 3.3V is in the upper left corner (the same side as the notch.) If your ribbon cable does not have a notch, be sure that the white stripe on the ribbon cable is on the top left when the cable is inserted into the cobbler.

2 About the full-size breadboard Depending upon which breadboard you are using, you may have a "full-size" breadboard (such as the one shown below) that is actually two half-size breadboards. If the breadboard you own has a gap in the painted lines (the rails red and blue at the top and bottom), then these rails are not electrically connected. In which case, you will need to add a wire (jumper) to connect the rails of the two halves of the breadboard together (as shown in the bottom part of the photo below.) Setup Wire the breadboard as shown in the figure below: (Note: use the notch on the Cobbler connector to locate pin 1 when wiring the circuit.) See this nifty Fritzing diagram contributed by Brent Stains.

3 This one wiring setup will work for homework Parts 1, 2 and 3 in this section. Remember that the longer lead of the LED is the positive (+) lead. Also be sure to use 3.3V (pin 1) and not 5V (pin 2)! Part 1: Lesson 2-2 Part 1: Run the sample code to turn an LED on and off In this assignment, you will work with GPIO pins as output devices, in order to turn and LED on and off (blink the LED). Download and unzip the GPIOLEDTest.zip NetBeans Project from Supporting Materials Open the project and review the code. Make sure your Raspberry Pi is running the AMS: sudo./usertest.sh Testing Run the project. The green LED should blink on and off 8 times and then stay on. Click Stop in the device emulator and the LED should turn off. Troubleshooting If the LED's do not light up: Check your wiring - make sure you have the ribbon cable oriented correctly, and that you have 3.3V connected to the + (red) rail. Try rotating them 180 degrees - the long lead should be +, but occasionally LED's don't have a longer lead. Modify the code to use pin 24 (the red LED) instead of pin 23. Modify the code so that both LED's blink at the same time Modify the blink method to pass in a blink rate and try different blink rates. Part 2: Lesson 2-2 Part 2: Run the sample code to read a switch In this assignment, you will work with GPIOPins as inputs, using a PinListener to determine when a switch is pressed and released. Download and unzip GPIOSwitchTest.zip Open the GPIOSwitchTest project and review the code. Make sure your Raspberry Pi is running the AMS: sudo./usertest.sh Testing Run your GPIOSwitch project and you should see "true" printed to console output when the button is pressed "false" is printed to the console when the button is released Troubleshooting: You never see any truemessages: Make sure that you have the switch wired properly. Use either set of opposing switch leads - if you have both jumper wires on the top or bottom set of switch leads, you are never completing the circuit. See this image:

4 You get true/false/false/false/true/true or a random set of the true and false messages: Make sure that you have the switch connected to ground through the pull-down (10K) resistor. If the pin "floats" it will not have a consistent low or high potential. Modify the code to use a rising edge trigger and change the code accordingly. Part 3: Lesson 2-3: Create a Door Sensor In this assignment, you will work with GPIO Pins and create a circuit and Java ME Embedded IMlet to turn one LED when the door switch is open (unpressed) and turn on another LED when the door switch is closed (pressed). Step 1: Build the MOOCData.jar file and create the MOOCData Library in NetBeans. Download and unzip the MOOCData.zip project from the Supporting Materials section. Briefly, this project contains the interface definitions and supporting code for the projects in the rest of the course. You will be adding this library to most of your projects in this course going forward. Open the MOOCData project in NetBeans. Right-click the project and select Build - this will create a jar file in the dist folder of the project. Right-click the MOOCData project and select Generate Javadoc. Bookmark the HTML file that opens in your browser. In NetBeans, click Tools > Libraries In the bottom left corner of the Library Manager, click New Library... Enter MOOCData as the Library Name and click OK With the Classpath tab selected, click Add JAR/Folder Use the explorer window to navigate to the folder where the MOOCData project is, and then into the dist folder. Select MOOCData.jar and click Add JAR/Folder. Click the Sources tab Click Add Jar/Folder Navigate to the MOOCData/src folder Select mooc and click Add Jar/Folder Click the Javadoc tab Click Add ZIP/Folder Navigate to the MOOCData/dist folder Select javadoc and click Add Zip/Folder Click OK to close the Library Manager You now have a library that you can add to your projects going forward. You can close the MOOCData project if you wish. Step 2: Create the DoorProject Create a new Java Embedded Project called DoorProject with a MIDlet called DoorProject. Copy the GPIOLED class into this project. Right-click on Libraries in the project and select Add Library Scroll down until you find the MOOCData library you created and select it. Click Add Library. Create a class called DoorSensor that implements PinListener and SwitchSensor. This class manages the state of the two LEDs. Left-click on the light bulb with the red dot that appears to the left of the class definition and select Implement all abstract methods. Add a constructor that takes four integer arguments: the portid number, the switch pin ID, the door closed LED pin number, and the door open LED pin number Add a start method that creates instances of the switch and the two LEDs (use GPIOLED to construct the LED instances) Add a stop method that gracefully closes the open pins You will need to write method bodies for the valuechanged and getstate. You can ignore the getswitchdata method. The getstate method should return the current state of the switch (true or false) The valuechanged method performs the following tasks: If the value of the switch is true, turn the door closed LED on and the door open LED off If the value of the switch is false, turn the door closed LED off, and blink the open door LED three times and then leave it on Be sure to add the appropriate API permissions to your project:

5 MIDlet-Permission-1: jdk.dio.devicemgmtpermission "*:*" "open" MIDlet-Permission-2: jdk.dio.gpio.gpiopinpermission "*:*" Testing When the switch is pressed, the door is opened. The way the code should work is as follows: Both LED's will be off when the IMlet starts. Light the "closed door LED" (GREEN LED) when the IMlet runs Light the "opened door LED" (RED LED) when the button is pressed, and turn off the closed door LED. If the button remains pressed, flash the opened door LED three times (1 second intervals) and then the opened door LED will stay on until the button is released. When the button is released again (door closed), turn off the open door LED and light the closed door LED. If the button is released while the open door LED is flashing, terminate the flashing and light the closed door LED. Turn off both LED's when the IMlet is destroyed. Consider blinking the "closed door LED" a few times when the door closed event occurs. Create some type of message that includes a timestamp for the door open event and write that to the console. Part 4: Lesson 2-6: Read Temperature Using the BMP085/BMP180 I 2 C Device In this assignment, you will wire the BMP085/BMP180 Barometric Pressure/Temperature sensor using the breadboard in order to read the temperature from the "container" at over an extended period of time. Setup Wire the BMP-085/BMP-180 sensor as shown. Note that these two devices are functionally equivalent - the BMP-085 is shown. Note that you do not need to remove the wiring for the Door project. Here is the Fritzing diagram for the circuit (without the LEDs) courtesy of Brent Stains. Run the code Wire the BMP device following the instructions presented in the video. Be sure that you have wired the sensor correctly by running the i2cdetect command: sudo i2cdetect -y 1 You should see your device at address 77. Download the TemperatureSensor.zip file from the Supporting Materials Unzip the file and open the TemperatureSensor project in Netbeans Run the project and you should see the temperature printed to the console output in degrees Fahrenheit. Put your finger on the sensor (gently) to see that the temperature is rising. Look through the code and modify it so that it displays the temperature in Celsius instead. Troubleshooting I can see the device with i2cdetect, but I am not getting any data!

6 There is an oddity with this device that if you have power connected, but not ground (and possibly the other way around), i2cdetect will report the address, so it looks like the device is wired properly. So check your power and ground carefully. Did you remember to enable I2C on the Raspberry Pi? And did you reboot the Pi after enabling I2C? I am getting this error: Unexpected error in ME plugin: java.lang.nullpointerexception processing tempbarosensor.i2csensor This is actually a bug in the javac compiler which does not affect the running of the project. However, there is a work-around: In the project properties, set the Source/Binary Format of the project to JDK 7. Modify the TempSensorTest Midlet and device code to notify you when the temperature exceeds a specified threshold. For example, when the temperature in the container changes by more than +/- 10 degrees Celsius. Note: you probably want to read a baseline temperature first and then record changes from that baseline. Carefully use a heat source to elevate the temperature near the sensor to test your code. Add an LED that you turn on when the temperature threshold is exceeded. See this Fritzing diagram provided by Brent Stains. Add the code to read the barometric pressure - use the datasheet from the Supporting Materials to get the algorithm required to get the barometric pressure. Consider how you might combine the door access and temperature reading - what might you want to do when there is a door open event? Copyright 2008, 2013, Oracle and/or its affiliates. All rights reserved. About Beehive Team Collaboration