Berlin Clock

A full-stack implementation of the Berlin Clock (Mengenlehreuhr).

The clock displays the current time using lit lamps in a base-5 system:

• Top circle — blinks every second (on = even, off = odd)
• Row 1 — 4 red lamps, each = 5 hours
• Row 2 — 4 red lamps, each = 1 hour
• Row 3 — 11 lamps, each = 5 minutes (lamps 3, 6, 9 are red; rest yellow)
• Row 4 — 4 yellow lamps, each = 1 minute

Stack

Layer	Technology
Backend	C# · ASP.NET Core Minimal API (.NET 8)
Frontend	Svelte + TypeScript (Vite)

Prerequisites

• .NET 8 SDK
• Node.js 18+

Scripts

All dev tasks are handled by run.sh at the project root.

Start both servers

bash run.sh start

Starts the backend (http://localhost:5050) and the Vite dev server (http://localhost:5173) concurrently. Press Ctrl+C to stop both.

Stop both servers

bash run.sh stop

Kills any processes running on the backend ports (5000, 5001) and the frontend port (5173).

Run tests

bash run.sh test

Stops running services, runs backend unit tests (dotnet test), and runs the frontend TypeScript type check (npm run check).

Build for production

bash run.sh build

Builds the backend in Release mode and compiles the frontend bundle.

API

The backend exposes a single endpoint:

GET http://localhost:5050/time

Response:

{
  "seconds": true,
  "hoursTop":     [true, true, false, false],
  "hoursBottom":  [true, false, false, false],
  "minutesTop":   [true, true, true, false, false, false, false, false, false, false, false],
  "minutesBottom":[true, false, false, false]
}

Project Structure

berlin-clock/
├── backend/
│   ├── BerlinClock.Api/
│   │   ├── BerlinClock.cs          # Clock logic (pure, stateless)
│   │   ├── Program.cs              # HTTP server + /time endpoint
│   │   └── BerlinClock.Api.csproj
│   ├── BerlinClock.Tests/
│   │   ├── BerlinClockTests.cs     # Unit tests for clock logic
│   │   └── BerlinClock.Tests.csproj
│   └── BerlinClock.sln
├── frontend/
│   └── src/
│       ├── App.svelte              # Clock UI component
│       ├── app.css
│       ├── main.ts
│       ├── services/
│       │   └── ApiService.ts       # Fetches time from backend
│       ├── types/
│       │   └── ClockState.ts       # TypeScript types for clock state
│       └── utils/
│           └── clockUtils.ts       # Lamp computation helpers
├── run.sh                          # start | stop | test | build
└── README.md