Hallway Display Build
Hallway Display Build
Summary
Build a battery-powered e-ink panel for the hallway showing the day’s calendar, outside temperature, and bin day. Target: at least three months on a charge. Completed 2026-08-20.
Ongoing operation lives at hallway-display; this page is the historical build record.
Use Cases
| Need | Why |
|---|---|
| Calendar at a glance on the way out | Phone works but nobody checks it in the hallway |
| Outside temperature | Decides coat, every morning |
| Bin day reminder | The actual reason this got built |
Explicitly not interactive — no touch, no buttons. Anything requiring input belongs on a phone.
Hard- and Software
| Option | Cost | Pros | Cons |
|---|---|---|---|
| ESP32-C6 + 4.2” e-ink ✅ | ~€40 | Lowest sleep current; e-ink needs no power to hold an image | Slow refresh; no colour |
| ESP32-C3 + same panel | ~€32 | Cheaper | Higher sleep current — projected ~6 weeks, under target |
| Small LCD + mains power | ~€25 | Fast, colour | Needs a socket in the hallway. There isn’t one |
| Repurposed tablet | €0 | Already owned | Battery lasts a day; screen is a light source at night |
Selected: ESP32-C6 + 4.2” e-ink. The mains-power option was ruled out first — running a cable to that wall was the whole problem. Between the C6 and C3, sleep current alone decided it: the C3 missed the three-month target and the ~€8 difference is irrelevant against a rebuild.
Software: ESPHome, config in scripts/hallway-display/.
Plan / Phases
Phase 1 — Breadboard ✅
- Flash ESPHome to the C6, confirm Wi-Fi and OTA
- Drive the panel, confirm partial refresh works
- Measure sleep current with a meter — 41 µA
Phase 2 — Layout ✅
- Calendar, temperature, bin day on one screen
- Full refresh every 20 partials to clear ghosting
Phase 3 — Enclosure and mounting ✅
- Frame, battery mounted behind
- Hung by the door
Phase 4 — Operational entity ✅
- Create hallway-display with
change_history: trueand the current state
Open Questions
- Is three months achievable on one charge? → Yes. At a 15-minute wake interval, measured draw projects to ~5 months.
- Wake interval? → 15 min. Started at 5; the underlying data doesn’t change faster than 15, and the shorter interval cost most of the battery life for nothing.
Log
[2026-08-27] Firmware pinned after a battery scare
Battery dropped to a week’s charge remaining after an ESPHome upgrade. Sleep current had gone 41 µA → 1.2 mA. Rolled back and pinned to 2026.7.2; recorded on the entity page. The logs showed nothing — this was only visible on a meter and in the battery curve.
[2026-08-22] Wake interval raised to 15 min
Projected life went from 6 weeks to ~5 months. Should have started here.
[2026-08-20] Built, mounted, project completed
All four phases done. Operational entity created; project moved to completed/.
[2026-08-14] Project created, plan approved
Options table filled in and the C3 ruled out on sleep current before anything was bought.