pIOIO_PIR

For this project we're going to use Processing, a language built on Java to build an Android application that will be connected to a passive infrared motion sensor via the IOIO board. Every time the sensor detects movement, it will display "Moving" on the screen of the Android device.

The IOIO is a microcontroller and has very similar capabilities to an Arduino, except this microcontroller specifically plays nicely with Android devices. In this post, we'll be using the IOIO board for simple digital output, the most basic IOIO capability. We can also use the IOIO for pulse-width-modulated digital output and analog input.

If you're not familiar with using Processing to write Android applications check out this Android Processing Tutorial by Jer Thorp and the Android Processing Wiki. We'll specificially be using the PIOIO library for Processing by PinkHatSpike.

Here's what it will look like (link to Vimeo page):

Hardware used

Before we dig in to the code, you'll need to pick up this hardware. You can get most of it from Sparkfun.

• IOIO-OTG from Sparkfun
• Bluetooth USB Module Mini from Sparkfun
• Lithium Ion Polymer Battery - 3.7v 2500mAh from Adafruit
• Breadboard - Mini Modular (White) from Sparkfun
• Jumper Wires Premium 6" M/F from Sparkfun
• PIR Sensor (Rev B) by Parallax
• Nexus S 4G by Samsung (any Android phone will do)

LED wiring

The wiring for this project is extremely simple, only three connections are needed!

• Connect the GND pin to ground (GND) on the IOIO board
• Connect the VCC pin to 3.3v on the IOIO board.
• Connect the OUT pin to pin #1 on the IOIO board.

Step 1: Importing Libraries / Android

First we have to add appropriate IOIO libraries and parts of the Android API. Before you can import the PIOIO library to your Processing sketch, you have to download the library from here and put it in your libraries folder. After the library is in the libraries folder we bring it in to our project, this happens before the setup loop.

import ioio.lib.api.*;
import ioio.lib.api.exception.*;
import com.pinkhatproductions.pioio.*;

import android.view.Window;
import android.view.WindowManager;
import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.bluetooth.*;

Step 2: Adding global variables

Also before the setup loop, we name our LED and declare a boolean to control our light and an integer for our color.

2a. Name the sensor input variable and specify that it's a digital input.

DigitalInput PIRmove;

2b. Make a boolean to show if there's movement detected by the sensor.

boolean isMoving = false;

2c. Create an integer for our background color.

int bcolor = 0;

Step 3: Processing setup

The setup chunk is ran once at the begining of the sketch and is in the void setup() funtion, here we start the PIOIO communication and declare the size of our sketch as well as choose the orientation of our sketch.

3a. Instantiate pIOIO

  new PIOIOManager(this).start();

3b. Set the size of the Android application, you can specify specific pixel dimensions or have it auto-detect the display width and display height of the device. P3D is the render mode, in case later you need something to be 3D.

  size(displayWidth, displayHeight, P3D);

3c. Set the orientation of the Android application, here it's portrait but you could also choose orientation(LANDSCAPE) or not include this if you don't want to lock the orientation.

  orientation(PORTRAIT); //orientation of sketch

3d. Set the text that will be displayed on the screen to be center-aligned and centered vertically.

  textAlign(CENTER, CENTER);

3e. Set the size of the text to be 36 pixels.

  textSize(36);

Step 4: Processing draw loop

The draw loop is run ~60 times per second default and is in the void draw() function.

4a. Draw the background color of the sketch.

  background(bcolor);

4b. If-else statement where if movement is detected, the background color of the application turns white, the text color turns black and the text displays "Moving" in the center of the screen. If there is no movement, the background color of the application turns black, the text color turns white and the text displays "Not Moving".

  if (isMoving) {
    bcolor = 255;
    fill(0);
    text("Moving", 0, 0, width, height);
  }
  else {
    bcolor = 0;
    fill(255);
    text("Not Moving", 0, 0, width, height);
  }

Step 5: IOIO thread setup

The IOIO functionality resides in a separate paralell thread that is structured similarly to the Processing void setup() and void draw() functions. The IOIO setup is in the void ioioSetup(IOIO ioio) function and is basically Java and only executes if it's connected to the IOIO. The function declaration is followed by throws ConnectionLostException before the opening curly bracket.

In the IOIO thread setup we link our PIRmove variable to pin #1 on the board and declare that it is to be used for digital input.

  PIRmove = ioio.openDigitalInput(1);

Step 6: IOIO thread loop

The IOIO thread loop mirrors the functionality of the void draw() processing funtion, is also basically Java and also only executes if it's connected to the IOIO. The function declaration is also followed by throws ConnectionLostException before the opening curly bracket.

6a. The try block checks our pin to see if it's high or low. If it's high, the isMoving boolean returns true.

  try {
    isMoving = PIRmove.read();
    Thread.sleep(20);
  }

6b. The catch block is an exception handler and throws an error if there is an interruption.

  catch (ConnectionLostException e) {
  }

Run on device

Now you should be good to go. Before you run the application be sure to go to the Android menu in the Processing IDE and select "Sketch Permissions" and check off BLUETOOTH, BLUETOOTH_ADMIN, and INTERNET.

And that's it! Run the sketch and should see the application reacting to movement detected from the motion sensor!