RPi Zero W E-Paper Display

A lightweight, memory-efficient Rust application that turns a Raspberry Pi Zero W into a dedicated e-paper display server. Designed for the Waveshare 7.3" E Ink Spectra 6 (E6) Full Color E-Paper Display.

Features

• Web Configuration Interface — Configure image URL, refresh schedule, rotation, and mirroring from any browser
• Multiple Schedule Plans — Create named schedule plans (e.g., "Weekday", "Weekend") with different refresh intervals
• Per-Day Schedule Assignment — Assign different schedule plans to each day of the week
• Time-Based Refresh Scheduling — Configure different refresh intervals for different times of day within each plan
• Schedule Presets — Quick setup with Simple (24h), Day/Night, or Work Hours presets
• Image Processing Pipeline — Automatic scaling, rotation, mirroring, and Floyd-Steinberg dithering to the 6-color palette
• Grafana Integration — Perfect for displaying dashboards, weather data, or any rendered image
• Resource Efficient — Optimized for the Pi Zero W's limited resources (~3MB binary, minimal memory footprint)
• Systemd Service — Runs as a background service with automatic startup
• Backward Compatible — Automatically migrates legacy configurations to the new schedule format

Web Interface

Configure the display through a clean, mobile-friendly web interface. Features include:

• Image URL configuration with HTTP/HTTPS support
• Multiple named schedule plans with tabbed interface
• Per-day schedule assignment with visual day-of-week grid
• Time-based refresh periods within each plan
• Schedule presets for common use cases (Simple, Day/Night, Work Hours)
• Configurable display dimensions
• Rotation (0°, 90°, 180°, 270°)
• Horizontal and vertical mirroring
• Scale-to-fit option for automatic image resizing
• Quick actions: Refresh Now, Test Pattern, Clear Display

Supported Hardware

• Raspberry Pi Zero W (or any Raspberry Pi with GPIO/SPI)
• Waveshare 7.3" E Ink Spectra 6 (E6) Full Color E-Paper Display (800×480)
  • Model: EPD7IN3E
  • Colors: Black, White, Red, Yellow, Blue, Green (6 colors)

Installation

Prerequisites

• Raspberry Pi with Raspberry Pi OS (Lite recommended)
• SPI enabled (sudo raspi-config → Interface Options → SPI)
• Display connected to GPIO header

Quick Install

1. Download the latest release binary
2. Copy to the Pi:

   scp epaper-display pi@<your-pi-ip>:/tmp/

3. Install:

   sudo mkdir -p /opt/epaper-display
   sudo mv /tmp/epaper-display /opt/epaper-display/
   sudo chmod +x /opt/epaper-display/epaper-display

4. Create config file /opt/epaper-display/config.json:

   {
     "image_url": "",
     "schedule_plans": [
       {
         "name": "Default",
         "periods": [
           { "start_time": "00:00", "end_time": "00:00", "interval_min": 60 }
         ]
       }
     ],
     "day_assignments": {
       "Mon": "Default",
       "Tue": "Default",
       "Wed": "Default",
       "Thu": "Default",
       "Fri": "Default",
       "Sat": "Default",
       "Sun": "Default"
     },
     "rotation": 0,
     "mirror_h": false,
     "mirror_v": false,
     "scale_to_fit": true
   }

5. Run:

   sudo /opt/epaper-display/epaper-display --config /opt/epaper-display/config.json --port 8888

6. Open http://<your-pi-ip>:8888 in a browser

Systemd Service

Create /etc/systemd/system/epaper-display.service:

[Unit]
Description=E-Paper Display Server
After=network.target

[Service]
Type=simple
ExecStart=/opt/epaper-display/epaper-display --config /opt/epaper-display/config.json
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

Enable and start:

sudo systemctl daemon-reload
sudo systemctl enable epaper-display
sudo systemctl start epaper-display

Configuration

Setting	Description	Default
image_url	URL to fetch the image from	""
schedule_plans	Array of named schedule plans (see below)	Single "Default" plan
day_assignments	Map of weekday to schedule plan name	All days → "Default"
display_width	Target display width in pixels	800
display_height	Target display height in pixels	480
rotation	Image rotation (0, 90, 180, 270)	0
rotate_first	Apply rotation before mirroring	true
mirror_h	Mirror image horizontally	false
mirror_v	Mirror image vertically	false
scale_to_fit	Scale image to fill display	true
web_port	Web server port	8888
verbose	Enable verbose logging	false

Schedule Plans

Schedule plans allow you to define different refresh schedules and assign them to specific days of the week. Each plan contains an array of time-based periods.

Schedule Plan Structure:

• name — Unique name for the plan (e.g., "Weekday", "Weekend")
• periods — Array of time periods, each with:
  • start_time — Start time in HH:MM format (24-hour)
  • end_time — End time in HH:MM format (24-hour)
  • interval_min — Refresh interval in minutes for this period

Periods within a plan must cover all 24 hours without gaps or overlaps. Use 00:00 to 00:00 for a single 24-hour period.

Example: Weekday/Weekend Schedules

{
  "schedule_plans": [
    {
      "name": "Weekday",
      "periods": [
        { "start_time": "06:00", "end_time": "09:00", "interval_min": 5 },
        { "start_time": "09:00", "end_time": "18:00", "interval_min": 15 },
        { "start_time": "18:00", "end_time": "22:00", "interval_min": 10 },
        { "start_time": "22:00", "end_time": "06:00", "interval_min": 60 }
      ]
    },
    {
      "name": "Weekend",
      "periods": [
        { "start_time": "08:00", "end_time": "23:00", "interval_min": 30 },
        { "start_time": "23:00", "end_time": "08:00", "interval_min": 120 }
      ]
    }
  ],
  "day_assignments": {
    "Mon": "Weekday",
    "Tue": "Weekday",
    "Wed": "Weekday",
    "Thu": "Weekday",
    "Fri": "Weekday",
    "Sat": "Weekend",
    "Sun": "Weekend"
  }
}

Example: Simple 24-Hour Schedule

{
  "schedule_plans": [
    {
      "name": "Default",
      "periods": [
        { "start_time": "00:00", "end_time": "00:00", "interval_min": 60 }
      ]
    }
  ],
  "day_assignments": {
    "Mon": "Default",
    "Tue": "Default",
    "Wed": "Default",
    "Thu": "Default",
    "Fri": "Default",
    "Sat": "Default",
    "Sun": "Default"
  }
}

Building from Source

Requirements

• Rust toolchain (1.70+)
• Cross-compilation target: aarch64-unknown-linux-gnu

Build

# Add target
rustup target add aarch64-unknown-linux-gnu

# Build release
cargo build --release --target aarch64-unknown-linux-gnu

The binary will be at target/aarch64-unknown-linux-gnu/release/rpizerow-epaper-display.

Use Cases

• Home Dashboard — Display weather, calendar, or smart home status
• Grafana Dashboards — Render and display monitoring dashboards
• Digital Signage — Low-power information display
• Art Display — Show rotating artwork or photos

License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.