What is behind Android Things?
Google's latest coup is called Android Things. This is an operating system specifically developed for the embedded sector with a focus on the Internet of Things (IoT). Google has slightly modified the Android architecture for this purpose. The OS does not boot into a launcher like on smartphones, but directly into an app. There are no other applications pre-installed, and the Google Play Store is not even available. The operating system does not necessarily require a screen. Furthermore, standard interfaces such as UART, SPI, I2C, etc. can now be accessed. This allows developers to connect modules to the device and communicate with them.
If you take a look at the new architecture (see Fig. 1) and compare it with the standard architecture of Android (see Google), the new “Things Support Library” (TSL) module is noticeable. What does this additional module mean? I deliberately chose two colors in the layered architecture shown. Components managed by Google are shown in blue. This means that Google provides the code and maintains it (monthly security patches). However, this also means for developers that they should not modify the Hardware Abstraction Layer (HAL). This is why Google introduced the TSL. If drivers are required, e.g. for a GPS module, the developer can still program and integrate them. All elements managed by the developer are shown in orange. This has the advantage that they can concentrate fully on the application.
The architecture has a particularly positive impact on security. The system cannot be modified at will by any manufacturer. Smartphones often have the problem that every major smartphone manufacturer pre-installs bloatware and makes significant changes, making updates difficult. This is a nightmare scenario for a permanently connected IoT or medical device. Security updates are therefore always installed as soon as they are available from Google and the device is connected to the internet. Of course, you can also set schedules or block updates while the device is in use. It's an unpleasant prospect if the device displays a message in the middle of the operating room: "The device will be available again soon, please wait."
Features
Google touts several features that are intended to set Android Things apart from other IoT operating systems. The large number of libraries and ready-made BSPs should enable a quick start and significantly reduce development costs. There's no need to worry about power management, such as low-power modes in inactive states. The operating system manages this independently. Internet communication is also particularly important for today's medical devices. Wi-Fi and Ethernet are therefore already implemented and can be used immediately. The Android Things console is an online platform where all builds and security updates are managed, and these can be sent as OTA updates to all internet-connected devices. Development and testing of the OS is free of charge. Small licensing fees apply when the product is released.
Toolchain
Anyone who has already programmed Android apps will appreciate the free IDE. Android Things applications can also be developed using Android Studio, the Android SDK, and the associated GUI editor. It's a very convenient development environment for designing beautiful apps. Programming and debugging work wirelessly via Wi-Fi or Ethernet. A built-in resource monitor lets you keep an eye on how much RAM is needed and how much CPU usage is being used. All Android libraries can also be used in Android Things. However, some services and intents have been removed. You can find out more about this on the official Google website.
Android Things in medical devices
Android Things could also be used for medical devices. We have already conducted some tests in this area. In a previous blog post, I already showed how An ECG monitor was implemented using Android Things (https://medtech-ingenieur.de/ekg-monitor-mit-android/) This ECG monitor is used by MEDtech-Ingenieur for testing in hardware development. A Raspberry Pi is currently being used. Data can be transferred from an ECG processor to the Raspberry Pi via USB CDC. This has a switchable 50 Hz software filter and graphs for displaying the ECG. If the developer wants to record specific events and later evaluate them with MatLab, the current display can be paused and saved as a CSV file on a USB stick.
This initial test has shown us that implementing a medical device with Android Things is both feasible and worthwhile. MEDtech-Ingenier will continue to pursue the use of Android Things in medical devices in the future, enabling us to create modern user interfaces with multi-touch and high-resolution screens for our customers.