• Monaco Editor — Full C++ / Python editor with syntax highlighting, autocomplete, minimap, and dark theme
• Multi-file workspace — create, rename, delete, and switch between multiple .ino / .h / .cpp / .py files
• Arduino compilation via arduino-cli backend — compile sketches to .hex / .bin files
• Compile / Run / Stop / Reset toolbar buttons with status messages
• Compilation console — resizable output panel showing full compiler output, warnings, and errors

• Real ATmega328p / ATmega2560 / ATmega32u4 / ATtiny85 emulation at native clock speed via avr8js
• Full GPIO — PORTB, PORTC, PORTD (Uno/Nano/Mega); all ATtiny85 ports (PB0–PB5)
• Timer0/Timer1/Timer2 — millis(), delay(), PWM via analogWrite()
• USART — full transmit and receive, auto baud-rate detection
• ADC — analogRead(), voltage injection from potentiometers on canvas
• SPI — hardware SPI peripheral (ILI9341, SD card, etc.)
• I2C (TWI) — hardware I2C with virtual device bus
• ATtiny85 — all 6 I/O pins, USI (Wire), Timer0/Timer1, 10-bit ADC; uses AttinyCore
• ~60 FPS simulation loop via requestAnimationFrame

• Real RP2040 emulation at 133 MHz via rp2040js — ARM Cortex-M0+
• All 30 GPIO pins — input/output, event listeners, pin state injection
• UART0 + UART1 — serial output in Serial Monitor; Serial input from UI
• ADC — 12-bit on GPIO 26–29 (A0–A3) + internal temperature sensor (ch4)
• I2C0 + I2C1 — master mode with virtual device bus (DS1307, TMP102, EEPROM)
• SPI0 + SPI1 — loopback default; custom handler supported
• PWM — available on any GPIO pin
• WFI optimization — delay() skips ahead in simulation time instead of busy-waiting
• Oscilloscope — GPIO transition timestamps at ~8 ns resolution
• Compiled with the earlephilhower arduino-pico core

See docs/RP2040_EMULATION.md for full technical details.

• Real Xtensa LX6/LX7 dual-core emulation via lcgamboa/qemu
• Full GPIO — all 40 GPIO pins, direction tracking, state callbacks, GPIO32–39 fix
• UART0/1/2 — multi-UART serial, baud-rate detection
• ADC — 12-bit on all ADC-capable pins (0–3300 mV injection from potentiometers)
• I2C — synchronous bus with virtual device response
• SPI — full-duplex with configurable MISO byte injection
• RMT / NeoPixel — hardware RMT decoder, WS2812 24-bit GRB frame decoding
• LEDC/PWM — 16-channel duty cycle readout, LEDC→GPIO mapping, LED brightness
• WiFi — SLIRP NAT emulation (WiFi.begin("PICSimLabWifi", ""))
• Requires arduino-esp32 2.0.17 (IDF 4.4.x) — only version compatible with lcgamboa WiFi

See docs/ESP32_EMULATION.md for setup and full technical details.

• RV32IMC emulation in TypeScript — no backend, no QEMU, no WebSocket
• GPIO 0–21 via W1TS/W1TC MMIO registers (ESP32-C3); PB0–PB5 (CH32V003)
• UART0 serial output in Serial Monitor
• CH32V003 — RV32EC core at 48 MHz, 16 KB flash, DIP-8 / SOP package — ultra-compact
• Instant startup — zero latency, works offline
• CI-testable — same TypeScript runs in Vitest

See docs/RISCV_EMULATION.md for full technical details.

• Full BCM2837 emulation via qemu-system-aarch64 -M raspi3b
• Boots real Raspberry Pi OS (Trixie) — runs Python scripts directly
• RPi.GPIO shim — drop-in replacement for the GPIO library; sends pin events to the frontend over a text protocol
• GPIO 0–27 — output and input, event detection, PWM (binary state)
• Dual serial — ttyAMA0 for user Serial Monitor, ttyAMA1 for GPIO protocol
• Virtual File System — edit Python scripts in the UI, upload to Pi at boot
• Multi-board serial bridge — Pi ↔ Arduino serial communication on the same canvas
• qcow2 overlay — base SD image never modified; session changes are isolated

See docs/RASPBERRYPI3_EMULATION.md for full technical details.

• Live serial output — characters as the sketch/script sends them
• Auto baud-rate detection — reads hardware registers, no manual configuration needed
• Send data to the RX pin from the UI
• Autoscroll with toggle

• 48 electronic components from wokwi-elements
• Component picker with search, category filters, and live previews
• Drag-and-drop repositioning on the simulation canvas
• Component rotation in 90° increments
• Property dialog — pin roles, Arduino pin assignment, rotate & delete

• Wire creation — click a pin to start, click another pin to connect
• Orthogonal routing — no diagonal paths
• 8 signal-type wire colors: Red (VCC), Black (GND), Blue (Analog), Green (Digital), Purple (PWM), Gold (I2C), Orange (SPI), Cyan (USART)
• Segment-based wire editing — drag segments perpendicular to their orientation

• Browse and install the full Arduino library index directly from the UI
• Live search, installed tab, version display

• Email/password and Google OAuth sign-in
• Project save with name, description, and public/private visibility
• Project URL — each project gets a permanent URL at /project/:id
• Sketch files stored on disk per project (accessible from the host via Docker volume)
• User profile at /:username showing public projects

• Built-in examples including Blink, Traffic Light, Button Control, Fade LED, Serial Hello World, RGB LED, Simon Says, LCD 20×4, and Pi + Arduino serial control
• One-click loading into the editor

# Pull and run
docker run -d \
  --name velxio \
  -p 3080:80 \
  -v $(pwd)/data:/app/data \
  ghcr.io/davidmonterocrespo24/velxio:master

Open http://localhost:3080.

The /app/data volume contains:

• velxio.db — SQLite database (users, projects metadata)
• projects/{id}/ — sketch files per project

git clone https://github.com/davidmonterocrespo24/velxio.git
cd velxio
cp backend/.env.example backend/.env   # edit as needed
docker compose -f docker-compose.prod.yml up -d

Prerequisites: Node.js 18+, Python 3.12+, arduino-cli

git clone https://github.com/davidmonterocrespo24/velxio.git
cd velxio

# Backend
cd backend
python -m venv venv && source venv/bin/activate  # Windows: venv\Scripts\activate
pip install -r requirements.txt
uvicorn app.main:app --reload --port 8001

# Frontend (new terminal)
cd frontend
npm install
npm run dev

Open http://localhost:5173.

arduino-cli setup (first time):

arduino-cli core update-index
arduino-cli core install arduino:avr

# For Raspberry Pi Pico / Pico W:
arduino-cli config add board_manager.additional_urls \
  https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
arduino-cli core install rp2040:rp2040

# For ESP32 / ESP32-S3 / ESP32-C3:
arduino-cli config add board_manager.additional_urls \
  https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
arduino-cli core install esp32:[email protected]

velxio/
├── frontend/                    # React + Vite + TypeScript
│   └── src/
│       ├── pages/               # LandingPage, EditorPage, UserProfilePage, ...
│       ├── components/          # Editor, simulator canvas, modals, layout
│       ├── simulation/          # AVRSimulator, RP2040Simulator, RiscVCore,
│       │                        # RaspberryPi3Bridge, Esp32Bridge, PinManager
│       ├── store/               # Zustand stores (auth, editor, simulator, project, vfs)
│       └── services/            # API clients
├── backend/                     # FastAPI + Python
│   └── app/
│       ├── api/routes/          # compile, auth, projects, libraries, simulation (ws)
│       ├── models/              # User, Project (SQLAlchemy)
│       ├── services/            # arduino_cli, esp32_worker, qemu_manager, gpio_shim
│       └── core/                # config, security, dependencies
├── wokwi-libs/                  # Local clones of Wokwi repos
│   ├── wokwi-elements/          # Web Components for electronic parts
│   ├── avr8js/                  # AVR8 CPU emulator
│   ├── rp2040js/                # RP2040 emulator
│   └── qemu-lcgamboa/           # QEMU fork for ESP32 Xtensa emulation
├── img/                         # Raspberry Pi 3 boot images (kernel8.img, dtb, OS image)
├── deploy/                      # nginx.conf, entrypoint.sh
├── docs/                        # Technical documentation
├── Dockerfile.standalone        # Single-container production image
├── docker-compose.yml           # Development compose
└── docker-compose.prod.yml      # Production compose