This sample shows how to implement a sensor hub on Android Things that collects sensor data from connected sensors and publish on a Google Cloud IoT PubSub topic.
The sample showcases a sensor-based device publishing data to Google Cloud IoT Core. Sensors can be added or removed dynamically, and the device will reconnect automatically to the cloud when power or connectivity is lost.
Sensor data collected since the last publish is sent through Cloud IoT every 20 seconds. The amount of data sent depends on the mode of each sensor:
- Continuous: Continuous mode sensors (temperature and pressure) publish only the most recent value.
- On-Change: On-Change mode sensors (motion detection) store up to 10 change events in between publications.
- Android Things compatible board
- Android Studio 2.2+
- 1 bmp280 temperature and pressure
- 1 PIR motion detector sensor
- Google Cloud Platform project with Cloud IoT support
On Android Studio, click on the "Run" button. If you prefer to run on the command line, type
./gradlew installDebug
adb shell am start com.example.androidthings.sensorhub/.SensorHubActivity
This sample will create a key pair (private and public) on the device on the first run. The private key will be saved to the Android Keystore, using a secure hardware if one is available. The public key will be printed to logcat and will be available as a file on your external storage location.
You will need the public key to register your device to Google Cloud IoT. Here's how you can fetch it:
adb pull /sdcard/cloud_iot_auth_certificate.pem
or, depending on your platform:
adb -d shell "run-as com.example.androidthings.sensorhub cat /data/user/0/com.example.androidthings.sensorhub/files/cloud_iot_auth_certificate.pem" > cloud_iot_auth_certificate.pem
A new keypair is only generated again when the device is reflashed.
With the cloud_iot_auth_certificate.pem file, you can register your device on
Google Cloud IoT:
gcloud iot devices create <DEVICE_ID> --project=<PROJECT_ID> --region=<CLOUD_REGION> --registry=<REGISTRY_ID> --public-key path=cloud_iot_auth_certificate.pem,type=rs256
Where:
DEVICE_ID: your device ID (it can be anything that identifies the device for you)PROJECT_ID: your Cloud IoT project idCLOUD_REGION: the cloud region for project registryREGISTRY_ID: the registry name where this device should be registered
Now that your device's public key is regsitered to Google Cloud IoT, you can set the device so that it can publish the sensor data to the Cloud IoT MQTT:
adb shell am startservice -a com.example.androidthings.sensorhub.mqtt.CONFIGURE -e project_id <PROJECT_ID> -e cloud_region <CLOUD_REGION> -e registry_id <REGISTRY_ID> -e device_id <DEVICE_ID> com.example.androidthings.sensorhub/.cloud.CloudPublisherService
If the registration and configuration steps were executed successfully, your device will immediately start to publish sensor data to Google Cloud IoT.
Take a look at the Google Cloud IoT documentation to learn how to pipe the data published by your devices into the other Google Cloud services.
Copyright 2016 The Android Open Source Project, Inc.
Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
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