device-envoy

Build Pico applications with LED panels, easy WiFi, and composable device abstractions.

device-envoy explores application-level device abstractions in embedded Rust using the Embassy async framework. It focuses on building reusable, typed async APIs that hide timing, interrupts, channels, and shared state inside each device.

device-envoy sits above HALs and drivers, modeling devices as long-lived async tasks with typed APIs rather than pin-level control.

Currently targeting Raspberry Pi Pico 1 and Pico 2 (ARM cores). RISC-V core support exists but is not actively tested.

Status

⚠️ Alpha / Experimental (version 0.0.2-alpha)

The API is actively evolving. Not recommended for production use, but excellent for experimentation and embedded Rust learning.

Background: See How Rust & Embassy Shine on Embedded Devices by Carl M. Kadie and Brad Gibson.

Features

• LED Panels & Strips - NeoPixel-style (WS2812) LED arrays with 2D text rendering, animation, and embedded-graphics support
• WiFi (Pico W) - Connect to the Internet with automatic credentials management. On boot, opens a web form if WiFi credentials aren't saved, then connects seamlessly to stored networks. Requires Pico W; WiFi is not supported on non-W boards.
• Button Input - Button handling with debouncing
• Servo Control - Servo positioning and animation
• Flash Storage - Type-safe, on-board persist storage
• LCD Display - Text display (HD44780)
• IR Remote - Remote control decoder (NEC protocol)
• RFID Reader - Card detection and reading (MFRC522)

Examples & Demos

The project includes examples (single-device tests) in examples/ and demo applications in demos/ showing real-world integration patterns:

• Basic LED Examples: Simple on/off control with blinky pattern
• LED Strip Examples: Simple animations, color control, text rendering
• LED Panel Examples: 12×4, 12×8, and multi-panel configurations with graphics
• Button Examples: Debouncing and state handling
• Servo Examples: Position sweeps and animation playback
• WiFi Examples: WiFi setup, time sync, DNS
• Flash Examples: Configuration persistence and data reset

See the examples/ and demos/ directories for complete runnable code.

Building & Running

Prerequisites

# Add Rust targets for Pico boards
rustup target add thumbv6m-none-eabi           # Pico 1 (ARM)
rustup target add thumbv8m.main-none-eabihf    # Pico 2 (ARM)

Quick Start

# Run examples using convenient aliases
cargo blinky                # Simple LED blinky (Pico 1)
cargo blinky-2              # Simple LED blinky (Pico 2)

cargo clock-lcd-w           # LCD clock with WiFi (Pico 1 WiFi)
cargo clock-lcd-2w          # LCD clock with WiFi (Pico 2 WiFi)

cargo clock-led12x4-w       # LED panel clock (Pico 1 WiFi)
cargo clock-led12x4-2w      # LED panel clock (Pico 2 WiFi)

# Check without running (faster builds)
cargo blinky-check          # Compile only
cargo clock-lcd-w-check     # Check Pico 1 WiFi version

# Build and check everything
cargo check-all

Tools:

• just - Optional command runner (install with cargo install just or your package manager). See justfile for commands.
• xtask - Project's custom automation tool (built-in, use via cargo xtask --help)

See .cargo/config.toml for all cargo aliases.

Hardware Notes

Standard Pinouts

Examples use conventional pin assignments for consistency:

• PIN_0: LED strip (8-pixel simple example)
• PIN_1: Single LED (blinky patterns) - Built-in LEDs are modeled as active-high (OnLevel::High) on all supported boards
• PIN_3: LED panel (12×4, 48 pixels)
• PIN_4: Extended LED panel (12×8, 96 pixels)
• PIN_5: Long LED strip (160 pixels, broadway/marquee effects)
• PIN_6: Large LED panel (16×16, 256 pixels)
• PIN_13: Button (active-low)
• PIN_11, PIN_12: Servo signals

Testing

Host-side tests run on your development machine without hardware:

# Run host tests (unit + integration)
cargo test --no-default-features --features defmt,host

# Or run via xtask
cargo xtask check-docs  # Includes doc tests

Tests include:

• LED text rendering comparisons against reference images
• 2D LED matrix mapping algebra
• LED color space conversions

License

Licensed under either:

• MIT license (see LICENSE-MIT file)
• Apache License, Version 2.0

at your option.