The solderless breadboard distributes 5 V and ground from the Arduino to the LCD, DHT22 pull-ups, contrast pot, and Ethernet shield support components. Clean power rails reduce mysterious LCD garbage and sensor timeouts.
Rail layout
- Red rail: 5 V from Arduino 5V pin (USB or barrel power when installed).
- Blue rail: Common ground tied to Arduino GND.
- Jumpers: Short, same-length wires where possible; one ground star point at the board.
LCD and sensor power
The 16×2 LCD draws modest current; DHT22 peaks during conversion. If cables run long to remote probes, consider a dedicated 5 V supply with common ground rather than starving the Uno regulator. Contrast pot wiring shares ground—see LCD GPIO map.
Bench verification
Measure rail voltage under load before sealing an enclosure. Troubleshooting steps live in circuit wiring troubleshooting. Full overview: Arduino circuit wiring.