This repository provides a modular embedded system targeting Raspberry Pi, combining:

• 🧠 Machine Learning inference in user space
• 📡 Custom kernel modules for sensor drivers
• 🧩 Modular services with linker set-based registration
• 🛠️ Yocto-based SDK for cross-compilation

This image outlines the architecture of the user-space application:

• Data flows from kernel drivers into queues
• Services (CLI, Telnet, Logging, etc.) communicate via queues
• ML model is integrated as a self-contained module
• All components register dynamically via linker sets

This project uses a unified messaging abstraction where services send messages to Queue<T> discovered via Linkersets. If a local handler Queue<T> is not found, the system automatically falls back to using Protobuf serialization and gRPC to communicate with a remote server.

This project uses Protocol Buffers for message serialization between local and remote services. If a local queue is not found for a message, the system serializes it via Protobuf and sends it to a remote responder using gRPC.

📂 Protobuf: protobuf/

This project integrates gRPC as a fallback communication mechanism for service messages when no local queue is found. Messages are serialized using Protocol Buffers, and forwarded to a remote server over gRPC for further handling or execution.

• Local services use Queue<T> with automatic discovery via Linkersets

• When a queue is not available locally, the message is serialized using Protobuf

• The serialized message is sent over gRPC to a remote server, which deserializes and handles it

📂 Protobuf definitions used for gRPC communication: protobuf/

This design allows seamless scaling from single-device embedded systems to distributed architectures involving multiple remote processing nodes.

. ├── KernelSpace/Drivers # Linux kernel modules for various physical sensors ├── UserSpace/Application # User space application with various services └── README.md 

Linker sets allow components to register themselves at link time, enabling automatic discovery and activation at runtime. This approach eliminates the need for manual initialization lists and supports a highly modular system.

/* AutoInit registation */ REGISTER_AUTO_INIT(CLI) // Register class for startup /* Cli Command registation */ REGISTER_CLI_COMMAND_BOTH("loglevel", Logging, setLevel, getLevel) // Register CLI command /* Queue registation */ DECLARE_QUEUE_FRIEND(Example, ExampleQ) // Declare friend REGISTER_PRIVATE_QUEUE(Example, ExampleQ, "ExampleQ") // Register Q to be used by Example

This modular design avoids centralized registration, improves scalability, and simplifies extension.

On your Yocto build machine:

# nano embd_linux/build_pi/conf/local.conf PACKAGECONFIG:append:pn-gcc-runtime = " static-libstdc++" DISTRO_FEATURES:append = " staticdev" SDKIMAGE_FEATURES:append = " staticdev-pkgs"

# cd ~/embd_linux source poky/oe-init-build-env build_pi bitbake -c cleansstate gcc-runtime bitbake gcc-runtime bitbake core-image-minimal -c populate_sdk

This will generate a .sh installer:

# poky-glibc-x86_64-core-image-minimal-cortexa7t2hf-neon-vfpv4-raspberrypi3-toolchain-4.0.21.sh tmp/deploy/sdk/poky-glibc-x86_64-<sdkname>-armv7at2hf-neon-toolchain-*.sh

Then on your dev system:

# cd tmp/deploy/sdk chmod +x poky-*.sh ./poky-*.sh

Source the environment to use it:

source /opt/poky/4.0.21/environment-setup-cortexa7t2hf-neon-vfpv4-poky-linux-gnueabi

cd UserSpace/Application mkdir build && cd build cmake .. make -j$(nproc)

The output binary will be:

build/binaries/EmbeddedApp 

cd KernelSpace/ source poky/oe-init-build-env build_pi bitbake virtual/kernel -c devshell

scp build/binaries/EmbeddedApp <root>@<192.168.178.98>:/home/ ssh <root>@<192.168.178.98> chmod +x /home/EmbeddedApp

sudo nano /etc/systemd/system/EmbeddedApp.service

Paste:

[Unit] Description=EmbeddedApp After=network.target [Service] ExecStart=/home/EmbeddedApp Restart=on-failure User=root WorkingDirectory=/home RestartSec=3 StandardOutput=journal StandardError=journal [Install] WantedBy=multi-user.target

[sudo] systemctl enable EmbeddedApp.service [sudo] systemctl start EmbeddedApp.service

systemctl status EmbeddedApp.service journalctl -u EmbeddedApp.service

This project is provided for educational and reference purposes only.

Redistribution, modification, or commercial use is strictly prohibited without prior written permission.

© 2025 Kishwar Kumar – All rights reserved.