Build Your SpojBoard

Complete parts list, assembly instructions, and configuration guide for both hardware options.

Choose Your Hardware

SpojBoard supports two hardware configurations:

Option 1: MatrixPortal S3

Recommended

Plug & play setup with built-in HUB75 connector

Required Parts

MatrixPortal ESP32-S3 Adafruit board with built-in HUB75 connector $24.95
HUB75 LED Matrix (64×32) Two panels for 128×32 display $15-25 each
USB-C Power Supply 5V 2A minimum (3A recommended) $8-15

Total: ~$65-90

Optional Accessories
  • Mounting hardware (screws, standoffs)
  • Custom enclosure (3D printed or laser cut acrylic frame)

Option 2: Generic ESP32-S3

Budget-Friendly

Affordable option with manual wiring

Required Parts

ESP32-S3-DevKitC-1 8MB flash, 2MB PSRAM minimum $8-12
HUB75 LED Matrix (64×32) Two panels for 128×32 display $15-25 each
HUB75 Cable with Breakout* Rainbow cable with dupont connectors $3-5
5V Power Supply 5V 2A minimum (3A recommended) $8-12

Total: ~$55-80

Wiring Notes: Standard HUB75 rainbow cable with dupont connectors to ESP32-S3 GPIO pins.

→ See Wiring Guide for complete pinout

* Usually included with LED display panels, but varies by vendor.

Power Requirements

Measured Power Consumption

Real-world testing results:

Normal operation (brightness 90) ~0.3A
Maximum brightness (255) ~0.7A peak
Transient spikes (WiFi, OTA, boot) Up to 1.6A

Recommended Power Supply

  • 5V 2A minimum (provides 2.8× headroom over normal peaks)
  • 5V 3A recommended (extra safety margin for all conditions)

Note: Published HUB75 specs often cite 5-6A at full brightness with all LEDs white, but SpojBoard's text-based display uses significantly less power.

Assembly Steps

1

Hardware Setup

MatrixPortal S3:

  1. Connect LED panels to HUB75 connector on MatrixPortal
  2. Chain second panel to first panel
  3. Connect panels to MatrixPortal's screw terminals (5V/GND)
  4. Connect USB-C to MatrixPortal for power and programming

Generic ESP32-S3:

  1. Wire HUB75 rainbow cable to ESP32-S3 GPIO pins (see Wiring Guide)
  2. Chain second panel to first panel
  3. Connect 5V power supply to panels via screw terminals (same PSU can power ESP32-S3)
  4. Connect USB-C to ESP32-S3 for programming (or power from panel PSU)
2

Flash Firmware

Prerequisites:

  • PlatformIO CLI or PlatformIO IDE (VS Code extension)
  • USB cable (USB-C)

Build & Flash:

git clone https://github.com/xbach/spojboard-firmware.git
cd spojboard-firmware
pio run -t upload

Or download pre-built firmware:

3

First Boot & WiFi Setup

  1. Power on — SpojBoard starts in AP mode (no WiFi configured)
  2. Connect to "SpojBoard-Setup" network from your phone/laptop
  3. Captive portal opens automatically (or navigate to 192.168.4.1)
  4. Enter WiFi credentials and save

Device reboots and connects to your WiFi network.

4

Web Configuration

  1. Find IP address — check your router's DHCP list or serial monitor
  2. Open web interface — navigate to http://<ip-address>/
  3. Configure transit stops:
    • Select your city (Prague or Berlin)
    • Enter stop IDs or names
    • Set refresh interval (default 60s)
  4. Optional: Configure weather, rest mode, custom line colors
  5. Save — settings persist across reboots
5

Test & Tune

  • Demo mode: Preview custom departures before API setup
  • Brightness: Adjust via web interface (default 90, range 0-255)
  • Scrolling: Enable for long destination names (off by default)
  • Dual ETA: Show two departure times per line (off by default)
  • Trip filtering: Minimum departure time to avoid "leaving now" entries (default 3 min)

Troubleshooting

Display not working

  • Check 5V power to LED panels
  • Verify HUB75 cable connections
  • Confirm correct firmware variant

WiFi not connecting

  • Hold BOOT button for 3 seconds → forces AP mode
  • Check WiFi credentials in setup portal
  • Verify 2.4GHz network (ESP32 doesn't support 5GHz)

No departures showing

  • Verify API credentials/stop IDs in web config
  • Check serial monitor for error messages
  • Enable debug mode + telnet logging

→ See Troubleshooting Guide for complete solutions

Enclosure Ideas

3D Printed Frame

  • Black ABS/PETG for sleek look
  • Snap-fit design for easy assembly
  • Cable routing channels

Laser Cut Acrylic

  • Black acrylic back plate + transparent front
  • M3 standoffs for LED panels
  • Minimalist design

Wall Mount

  • Keyhole slots on back for direct wall mounting
  • 3M command strips for damage-free installation

Community builds: Share your build on GitHub Discussions!

Ready to Start?

Get the firmware and start building your SpojBoard today.

Get Firmware on GitHub Read Documentation