Barnum - RP2040-ETH WS2812 Network Control

A network-controllable WS2812 LED system built on the Waveshare RP2040-ETH board. Control LED colors over ethernet using simple TCP commands.

Features

• Network Control: TCP server accepting color commands over ethernet
• Visual Feedback:
  • Green flash every 1s (firmware alive indicator)
  • Amber flash on network traffic (RX/TX activity)
  • Smooth color transitions between commands
• Real-time Response: Immediate color changes with network acknowledgments
• Debug Output: Comprehensive serial logging for troubleshooting

Hardware

• Board: Waveshare RP2040-ETH
• LED: WS2812/NeoPixel connected to GPIO 25
• Ethernet: CH9120 chip with built-in TCP/IP stack
• Power: USB-C for programming, external power for LED strips

Pin Configuration

Function	GPIO	Description
WS2812 Data	25	LED strip data line
UART TX (CH9120)	20	Serial to ethernet chip
UART RX (CH9120)	21	Serial from ethernet chip
CFG (CH9120)	18	Configuration mode pin
RES (CH9120)	19	Reset pin for ethernet chip

Network Configuration

• IP Address: 192.168.1.201
• Subnet Mask: 255.255.0.0
• Gateway: 192.168.1.1
• Mode: TCP Server
• Port: 1000

Supported Commands

Send these as TCP messages to port 1000:

Command	Effect
RED	Set LED to red
GREEN	Set LED to green
BLUE	Set LED to blue
WHITE	Set LED to white
OFF	Turn LED off
RGB:r,g,b	Custom color (e.g., RGB:255,128,0 for orange)

Building

# Setup (first time)
git clone <this-repo>
cd barnum

# Build
mkdir -p build
cd build
cmake ..
make barnum

# Flash
# 1. Hold BOOTSEL button on RP2040-ETH
# 2. Connect USB-C cable
# 3. Copy barnum.uf2 to RPI-RP2 drive
# 4. Board reboots automatically

Usage Examples

Python Client

import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect(('192.168.1.201', 1000))
sock.send(b'RED')
response = sock.recv(1024)
print(response.decode())  # "Setting color to R:255 G:0 B:0"
sock.close()

Command Line

# Test with netcat
echo "BLUE" | nc 192.168.1.201 1000

# Test with included Python client
python3 test_client.py GREEN
python3 test_client.py "RGB:255,0,255"

Network Testing

# Basic connectivity
ping 192.168.1.201

# Port scan
python3 test_ethernet.py

# Network discovery
python3 network_scan.py

Visual Indicators

1. Startup: 3 blue flashes (ethernet initialization)
2. Alive: Green flash every 1 second (firmware running)
3. Traffic: Amber flash on network activity
4. Commands: Smooth color transitions to target colors

Project Structure

barnum/
├── barnum.c              # Main application (network + LED control)
├── barnum-initial.c      # Original LED cycling demo
├── ch9120.c/.h           # CH9120 ethernet chip driver
├── ws2812.pio           # PIO program for WS2812 timing
├── CMakeLists.txt       # Build configuration
├── test_client.py       # Python test client
├── test_ethernet.py     # Network diagnostics
├── network_scan.py      # Network discovery tool
├── README_ETH.md        # Ethernet implementation details
└── rp-2040.md          # Hardware documentation

Troubleshooting

No Network Connectivity

1. Check ethernet cable connection
2. Verify green/amber LEDs on RJ45 connector
3. Monitor serial output for configuration errors
4. Ensure IP settings match your network

LED Not Responding

1. Verify WS2812 connection to GPIO 25
2. Check power supply to LED strip
3. Look for "Received command" in serial output

Build Issues

1. Ensure Pico SDK is properly installed
2. Check board type in CMakeLists.txt
3. Verify pico_sdk_import.cmake is present

Development Notes

• Built with Pico SDK 2.1.1
• Uses PIO for precise WS2812 timing
• CH9120 handles TCP/IP stack entirely
• Dual-core RP2040 allows concurrent LED/network operations
• Serial debug output at 115200 baud

Future Enhancements

• Multiple LED support
• Animation patterns
• Web interface
• MQTT integration
• Color persistence
• Network configuration via commands