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.