9.3 Controlling the Android Door Lock
Before we can write an elaborate server for the Android phone, we first need to write a test program that will validate the circuit we constructed in the last section.
Be sure to have installed the plug-ins for the
Android SDK and Eclipse IDE with the Android Development Tools on
your computer. Refer to Chapter 7, Web-Enabled Light
Switch, for the steps on how to configure the SDK and IDE
if you haven’t already done so. Then, download the HelloIOIO demo
project from the Sparkfun IOIO tutorial web page.[97] The HelloIOIO project is a
simple application that turns the IOIO’s onboard LED on and off. We
are going modify this simple application by declaring another
ToggleButton object in its
main.xml layout file. Then we’ll
add four lines of code to the MainActivity.java file that describe the added
ToggleButton action for digital pin 3
on the IOIO.
Import Sparkfun’s HelloIOIO project into the Eclipse environment via the File→Import→Existing Projects option. If you prefer, you can also load the modified HelloIOIO-PTS project available from this book’s code download page that has all the necessary code additions mentioned in this section.
All IOIO board projects rely on the custom
IOIOLib library that must be added
to each IOIO project. Use the following steps to do so:
-
Import the IOIOLib bundle into the Eclipse environment via the same File→Import→Existing Projects into Workspace menu option.
-
Highlight the HelloIOIO project in the Eclipse Package Explorer pane.
-
Access the Properties option from the Eclipse Project menu.
-
Select Android from the selections on the left column of the Properties dialog box.
-
Click the Add... button. A Project Selection dialog box should pop up listing the IOIOLib project. Highlight the IOIOLib item and click the OK button.
If IOIOLib was successfully imported, it should be listed with a green checkmark in the Library portion of the Properties dialog box, as shown in Figure 40, IOIOLib successfully imported and referenced.
Figure 40. IOIOLib successfully imported and referenced
With the IOIOLib properly referenced, edit the
/res/layout/main.xml file from the
HelloIOIO project. Add another ToggleButton object to the existing layout by
copying the existing TextView
description containing the ToggleButton description of the toggle button
used to turn on and off the IOIO’s onboard LED. Paste it in right
after the original TextView section.
Then, rename the android/id value of the copied toggle button to
android:id="@+id/powertailbutton". This
will be the reference accessed in the modified MainActivity class. The modified main.xml file should look like this:
| AndroidDoorLock/HelloIOIO-PTS/res/layout/main.xml | |
<?xml
version="1.0" encoding="utf-8"?> |
|
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
|
android:orientation="vertical" |
|
android:layout_width="fill_parent" |
|
android:layout_height="fill_parent"
> |
|
<TextView |
|
android:layout_width="fill_parent" |
|
android:layout_height="wrap_content" |
|
android:text="@string/txtLED" |
|
android:id="@+id/title" /> |
|
<ToggleButton android:text="ToggleButton" |
|
android:layout_width="wrap_content" |
|
android:layout_height="wrap_content" |
|
android:id="@+id/button" > |
|
</ToggleButton> |
|
<TextView |
|
android:layout_width="fill_parent" |
|
android:layout_height="wrap_content" |
|
android:text="@string/txtPowerTail" |
|
android:id="@+id/title" /> |
|
<ToggleButton android:text="ToggleButton" |
|
android:layout_width="wrap_content" |
|
android:layout_height="wrap_content" |
|
android:id="@+id/powertailbutton"
> |
|
</ToggleButton> |
|
</LinearLayout> |
|
Next, add the code for the second toggle button to
the MainActivity class that will turn
on and off the signal going to the PowerSwitch Tail. The first
addition is the powertailbutton_ =
(ToggleButton) findViewById(R.id.powertailbutton); line,
which associates the powertailbutton_
object with the powertailbutton toggle button defined in the
main.xml file.
With the user interface addition of the toggle
button for the PowerSwitch Tail, we can add the object reference to
the MainActivity class located in the
/src/ioio/examples/hello/pts/MainActivity.java
file:
| AndroidDoorLock/HelloIOIO-PTS/src/ioio/examples/hello/pts/MainActivity.java | |
private
ToggleButton button_; |
|
private
ToggleButton powertailbutton_; |
|
Instantiate the powertailbutton_ object in the MainActivity OnCreate
method, like this:
| AndroidDoorLock/HelloIOIO-PTS/src/ioio/examples/hello/pts/MainActivity.java | |
@Override |
|
public
void onCreate(Bundle
savedInstanceState) { |
|
super.onCreate(savedInstanceState); |
|
setContentView(R.layout.main); |
|
button_
= (ToggleButton) findViewById(R.id.button); |
|
powertailbutton_ = (ToggleButton)
findViewById(R.id.powertailbutton); |
|
} |
|
So when the main application window is created, the
toggle button for the PowerSwitch Tail will now be accessible via
the MainActivity class. All that
remains is the code needed to listen for the powertailbutton_ toggle action being turned on and
off:
| AndroidDoorLock/HelloIOIO-PTS/src/ioio/examples/hello/pts/MainActivity.java | |
class
IOIOThread extends
AbstractIOIOActivity.IOIOThread { |
|
/** The on-board LED. */ |
|
private DigitalOutput
led_; |
|
| ① |
private DigitalOutput powertail_;
|
/** |
|
* Called every time a connection with IOIO has
been established. |
|
* Typically used to open
pins. |
|
* |
|
* @throws
ConnectionLostException |
|
* When IOIO connection is
lost. |
|
* @see
ioio.lib.util.AbstractIOIOActivity.IOIOThread#setup() |
|
*/ |
|
@Override |
|
protected void setup() throws ConnectionLostException { |
|
led_ =
ioio_.openDigitalOutput(0, true); |
|
| ② |
powertail_ = ioio_.openDigitalOutput(3,true); |
} |
|
/** |
|
* Called repetitively while the IOIO is
connected. |
|
* |
|
* @throws
ConnectionLostException |
|
* When IOIO connection is
lost. |
|
* |
|
* @see
ioio.lib.util.AbstractIOIOActivity.IOIOThread#loop() |
|
*/ |
|
@Override |
|
protected void loop() throws ConnectionLostException { |
|
led_.write(!button_.isChecked()); |
|
| ③ |
powertail_.write(!powertailbutton_.isChecked()); |
try { |
|
sleep(10); |
|
}
catch (InterruptedException e)
{ |
|
} |
|
} |
|
} |
|
- ①
-
Initialize the
DigitalOutputpowertail_object. - ②
-
Assign the
powertail_object to the IOIO’s digital pin out 3. - ③
-
Turn on or off the digital signal (i.e., make it High or Low) to IOIO’s digital pin out 3 when the onscreen toggle button for the PowerSwitch Tail is toggled on or off.
When the onscreen PowerSwitch Tail toggle button is
switched on, it will instruct the powertailbutton_ instance to send a 5V signal from
digital pin 3. This in turn will electrify the PowerSwitch Tail
relay to power on, which will then electrify the 12V power adapter
that will ultimately electrify and release the lock.
Save your changes, compile the Android application, and install the modified HelloIOIO program on the phone. Check to ensure that your door hardware circuit is properly wired and powered. Then plug in the USB cable between the phone and the IOIO board and execute the modified HelloIOIO program on the phone.
If nothing happens, verify that the USB Debugging option is checked on the phone. Also, make sure your wiring is connected correctly. If you have access to a multimeter or an oscilloscope, check to see that 5 volts are flowing from the digital pin 3 when the onscreen PowerSwitch Tail toggle switch is set to the on position. If the output is less than 5 volts, there will not be enough of a signal from the IOIO board to electrify the PowerSwitch Tail and thus power the electric door latch.
Now that the hardware is working properly, we will network-enable the lock so we can open it by requesting a URL from a web server that we will add to this modified HelloIOIO program.