In this article, we will show you how you can connect Android Things to your Internet of Things (IoT) network easily with Alibaba Cloud IoT Platform. We will build a functional formaldehyde and temperature sensor for this project.

Hardware Devices

Project Device List

NXP i.MX7D Pins

NXP Pico i.MX7D full I/O interface document:

Device Wiring Diagram

Alibaba Cloud IoT Configuration

After setting up the hardware, it's time to configure the software on Alibaba Cloud IoT Platform.

First, navigate to the IoT console and activate Alibaba Cloud IoT. Create an advanced product and add product attribute definition:

Android Things Device Development

1. Create an Android Things project using Android Studio, and grant network permissions

   <uses-permission android:name="android.permission.INTERNET" />

   
   
2. Add the "eclipse.paho.mqtt" repository to gradle

   implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.2.0'

   
   
3. Read DHT12 data through I2C

   private void readDataFromI2C() {
   
           try {
   
               byte[] data = new byte[5];
               i2cDevice.readRegBuffer(0x00, data, data.length);
   
               // check data
               if ((data[0] + data[1] + data[2] + data[3]) % 256 != data[4]) {
                   humidity = temperature = 0;
                   return;
               }
               // humidity data
               humidity = Double.valueOf(String.valueOf(data[0]) + "." + String.valueOf(data[1]));
               Log.d(TAG, "humidity: " + humidity);
               // temperature data
               if (data[3] < 128) {
                   temperature = Double.valueOf(String.valueOf(data[2]) + "." + String.valueOf(data[3]));
               } else {
                   temperature = Double.valueOf("-" + String.valueOf(data[2]) + "." + String.valueOf(data[3] - 128));
               }
   
               Log.d(TAG, "temperature: " + temperature);
   
           } catch (IOException e) {
               Log.e(TAG, "readDataFromI2C error " + e.getMessage(), e);
           }
   
       }

   
   
4. Obtain Ze08CH2O data through UART

   try {
                   // data buffer
                   byte[] buffer = new byte[9];
   
                   while (uartDevice.read(buffer, buffer.length) > 0) {
   
                       if (checkSum(buffer)) {
                           ppbCh2o = buffer[4] * 256 + buffer[5];
                           ch2o = ppbCh2o / 66.64 * 0.08;
                       } else {
                           ch2o = ppbCh2o = 0;
                       }
                       Log.d(TAG, "ch2o: " + ch2o);
                   }
   
               } catch (IOException e) {
                   Log.e(TAG, "Ze08CH2O read data error " + e.getMessage(), e);
               }

   
   
5. Create an Alibaba Cloud IoT connection and report the data

   /*
   payload format
   {
     "id": 123243,
     "params": {
       "temperature": 25.6,
       "humidity": 60.3,
       "ch2o": 0.048
     },
     "method": "thing.event.property.post"
   }
   */
   MqttMessage message = new MqttMessage(payload.getBytes("utf-8"));
   message.setQos(1);
   
   String pubTopic = "/sys/" + productKey + "/" + deviceName + "/thing/event/property/post";
   
   mqttClient.publish(pubTopic, message);

Real-Time Data on Cloud Console

After the device is started, you can view the real-time data of the device on the Alibaba Cloud IoT console, Device Management -> Running Status.

Source Code

To get the source code for this project, visit the following GitHub page.