LCD local display format

Format on-site temperature and humidity LCD lines so you can validate probes on-site without opening a laptop.

Top view of a blue Arduino Uno microcontroller board on a white background
Arduino-compatible boards run the sketch that polls probes and publishes JSON. Photo: Wikimedia Commons contributor. CC0

The 16×2 LCD gives installers immediate feedback without Wi-Fi or a laptop. Two rows are tight: firmware usually rotates or splits probe 0, probe 1, and average across lines or timed pages.

Typical layout

  • Row 0: Probe 0 temp and humidity abbreviated (e.g. P0 38F 41%).
  • Row 1: Probe 1 or rolling average depending on sketch version.
  • Backlight: On during reads; optional timeout to reduce glare at night.

Units and refresh

Match units to what you expect on the website or label the LCD. Refresh only when new valid reads arrive: avoid flicker from partial updates. GPIO wiring: LCD GPIO map.

When LCD disagrees with web

Compare against live JSON via curl: JSON schema. Stale cache on Redis relay can lag the LCD; local display is often fresher.