minihil

minihil is development device which can be used for HWIL.

The docs introduce the tool and provide instructions on how to install, build, and use the MiniHIL software.

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About minihild

The core of the software is minihild — a POSIX C++ daemon running as a server on the Raspberry Pi target. It listens for incoming connections on TCP port 9000 and parses JSON-RPC 2.0 commands. It controls the Waveshare Relay Board (B) (an 8-channel relay board) via standard Linux character device GPIO controls (libgpiod v2).

It is designed with a decoupled architecture to allow easy expansion (e.g. adding WebSockets) and supports Software-in-the-Loop (SIL) simulation so that you can compile and test the server and its API directly on your local developer PC without Raspberry Pi hardware.

SIL (Software-in-the-Loop) Host Build

To compile and run the daemon locally on your developer PC in SIL mock mode:

Prerequisites

Install the required JSON header libraries:

sudo apt-get install nlohmann-json3-dev

Compile and Run

# Configure and compile using CMake
cmake -B sw/minihil/build -S sw/minihil
cmake --build sw/minihil/build

# Start the mock daemon
./sw/minihil/build/minihild

The daemon will boot in SIL mode and print: [SilRelayController] Software-in-the-Loop simulation initialized.

minihildesk GUI Client

minihildesk is a premium GTKmm-based C++ desktop GUI client designed to connect to the minihild server (either running on a Raspberry Pi target or locally in SIL mock mode).

It features:

  • A connection bar supporting standard TCP connection, SSL/TLS secure connection, and Mutual TLS (mTLS) client verification.

  • A grid of 8 Relay Control Cards displaying status via glowing LED indicators and active green borders.

  • Multi-mode relay control per channel: Toggle (manual switch), Timer (seconds spin-input), Pulse (milliseconds spin-input up to 100,000 ms), and Blink (ON/OFF ms inputs and cycle count).

  • Automatic hardware safety auto-off logic: switching modes on an active channel immediately turns the relay OFF on the server before entering the new mode.

  • A monospace green log terminal at the bottom showcasing outgoing and incoming JSON-RPC traffic.

Prerequisites

Install the GTKmm-4.0 development headers, OpenSSL, and JSON library:

sudo apt-get install libgtkmm-4.0-dev libssl-dev nlohmann-json3-dev

Compile and Run

# Configure and compile using CMake
cmake -B sw/minihildesk/build -S sw/minihildesk
cmake --build sw/minihildesk/build

# Start the desktop GUI app
./sw/minihildesk/build/minihildesk

Yocto Image Build (Raspberry Pi Target)

MiniHIL packages minihild into a custom Yocto Linux image (minihil-image) using meta-raspberrypi and Poky.

Prerequisites

Ensure your build host has all required packages for Yocto Scarthgap (refer to sw/rpi-base-platform/README.md for the list of packages).

Compile target image

# 1. Initialize environment (sources Poky and sets up configs/layers)
source sw/setup-env.sh

# 2. Trigger the bitbake build
bitbake minihil-image

This compiles the C++ application, bundles the systemd daemon config (minihil.service) to start automatically on boot, and outputs a flashable image.

JSON-RPC 2.0 API Specification

You can send JSON-RPC text frames (terminated by \n) to port 9000.

set_relay

Energize or de-energize a relay channel (1 to 8):

  • Request:

    {"jsonrpc": "2.0", "method": "set_relay", "params": {"relay_id": 3, "state": true}, "id": 1}

  • Response:

    {"jsonrpc": "2.0", "result": {"relay_id": 3, "state": true, "success": true}, "id": 1}

get_relays

Query states of all 8 relay channels:

  • Request:

    {"jsonrpc": "2.0", "method": "get_relays", "id": 2}

  • Response:

    {"jsonrpc": "2.0", "result": {"1": false, "2": false, "3": true, "4": false, "5": false, "6": false, "7": false, "8": false}, "id": 2}

start_timer

Keep a relay active for a specific duration in seconds:

  • Request:

    {"jsonrpc": "2.0", "method": "start_timer", "params": {"relay_id": 2, "seconds": 10}, "id": 3}

  • Response:

    {"jsonrpc": "2.0", "result": {"relay_id": 2, "seconds": 10, "success": true}, "id": 3}

start_pulse

Generate a single momentary pulse in milliseconds (up to 100,000 ms):

  • Request:

    {"jsonrpc": "2.0", "method": "start_pulse", "params": {"relay_id": 3, "duration_ms": 5000}, "id": 4}

  • Response:

    {"jsonrpc": "2.0", "result": {"relay_id": 3, "duration_ms": 5000, "success": true}, "id": 4}

get_relay_status

Query detailed diagnostic status and remaining time for a single channel:

  • Request:

    {"jsonrpc": "2.0", "method": "get_relay_status", "params": {"relay_id": 2}, "id": 6}

  • Response:

    {"jsonrpc": "2.0", "result": {"relay_id": 2, "status": "Channel 2: ON (Timer, rem: 8s)"}, "id": 6}