Introduction

Android Things, Google’s embedded operating system derived from Android, was designed to bring the Android developer experience to IoT devices. While it provides a robust framework for many applications, real-world IoT solutions often require interaction with specialized hardware or custom background logic that isn’t covered by the standard Android Things distribution. This tutorial will guide you through the expert-level process of customizing an Android Things OS image, specifically focusing on how to integrate custom kernel drivers (modules) and proprietary system services directly into your build.

By mastering these techniques, you can tailor Android Things to precisely fit your hardware requirements, enable low-level device control, and implement always-on background functionalities essential for professional IoT, automotive, and smart TV applications.

Prerequisites

• A Linux-based development machine (Ubuntu 18.04 LTS or newer recommended)
• At least 200GB free disk space and 16GB RAM
• A solid understanding of Linux command-line, kernel modules, and Android AOSP build system
• A compatible Android Things development board (e.g., an NXP i.MX based board like NXP i.MX7D Pico-i.MX6UL based board as Android Things is EOL and documentation for latest official version is scarce, but the underlying AOSP build process remains similar for previous versions)
• The Android Things AOSP source code synced locally

1. Setting Up Your Android Things AOSP Build Environment

Before diving into custom modifications, ensure your AOSP build environment is correctly set up and capable of building a standard Android Things image. This typically involves:

sudo apt-get install git-core gnupg flex bison gperf build-essential zip curl zlib1g-dev gcc-multilib g++-multilib libc6-dev-i386 libncurses5 lib32ncurses5-dev x11proto-core-dev libx11-dev lib32z1-dev libgl1-mesa-dev libxml2-utils xsltproc unzip fontconfig

mkdir ~/bin
PATH=~/bin:$PATH
curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
chmod a+x ~/bin/repo

mkdir android-things-aosp
cd android-things-aosp
repo init -u https://android.googlesource.com/platform/manifest -b android-things-1.0.4-release
repo sync -j8

source build/envsetup.sh
lunch aosp_imx7d_pico-userdebug # Or your specific board target

Replace android-things-1.0.4-release with the specific branch you intend to build, and aosp_imx7d_pico-userdebug with your board’s lunch target. A successful build should produce images in out/target/product/<board_name>.

2. Integrating a Custom Kernel Module (Driver)

Custom hardware often requires a custom kernel driver. We’ll add a simple