Ereader

Mini E-Reader

A pocket, frontlit e-paper reader you can build and hack. ESP32-S3 + 4.26" E-Paper (800×480) + tunable-white frontlight, USB-C charged, LiPo powered.

This repository holds the open hardware (KiCad) and project documentation for a small e-reader. Docs follow the Colophon method: a Brief (this file), Decisions (docs/adr/), a Log (docs/research-log.md), a Runbook (docs/runbook.md), and a Changelog.

One KiCad project, one source of truth. The board lives at the repo root: ereader.kicad_pcb, with the electrical design in the ereader-*.md docs — ereader-connection-list.md (net-by-net source of truth), ereader-schematic.md (subsystem schematic), ereader-pcb-design.md (full spec), ereader-footprints.md (BOM/footprint picklist) — and the ereader-kicad.net netlist. (Rev C — placed, planed, stitched, DRC-ruled; routing pending.) An earlier, simpler hardware/ reference spec was removed once ereader.* superseded it; the historical comparison is in docs/research-log.md. The Rev C parts are reconciled into the ADRs: 0006 (power) supersedes 0003 and 0007 (frontlight) supersedes 0005.

Why

Commercial e-readers are closed and hard to modify. This is a compact, documented reference design — cheap parts, two-layer board, hand- or JLCPCB-assemblable — for reading plain text / EPUB on a persistent, sunlight-readable display with an adjustable frontlight and Wi-Fi sync. A buildable learning platform, not a product.

Scope & non-scope

In scope

• Schematic + 2-layer PCB: MCU, 4.26" SPI E-Paper, tunable frontlight, power (USB-C + 1S LiPo), buttons, optional microSD.
• A bill of materials and fabrication-ready outputs.
• Automated ERC/DRC + gerber export in CI.

Out of scope (for now)

• Enclosure / industrial design (CAD).
• Firmware (tracked separately once hardware is proven).
• Touch input, audio, multi-panel support.
• Certification / mass production.

Success criteria

1. Schematic captured with ERC clean in KiCad 8.
2. PCB placed + routed with DRC clean; gerbers export in CI.
3. A built prototype: powers from USB and battery, charges, enumerates over native USB, refreshes the E-Paper, and lights the frontlight with independent brightness + colour-temperature control.

Capabilities

• Render text/EPUB to a 4.26" 800×480 monochrome E-Paper panel over SPI.
• Tunable-white frontlight: independent cold/warm channels, PWM brightness and colour-temperature mixing.
• Wi-Fi/BLE (ESP32-S3) for fetching and syncing books.
• Battery power (1S LiPo) with USB-C charging and USB-priority power path.
• Battery state-of-charge and charge-status telemetry.
• Three navigation buttons; BOOT/RESET jumper pads (screwdriver-shortable) for flashing.
• Optional microSD for local library storage.

Non-functional baseline

• Power: deep-sleep with the page retained in the µA range; runs from a single LiPo; charges over USB-C.
• Cost/build: two-layer FR-4, common parts, low-cost assembly.
• Serviceability: test points on key rails and buses; native-USB programming with no external bridge.
• Docs: every significant decision captured as an ADR before it is built.

Stack

• MCU: ESP32-S3-WROOM-1 (Wi-Fi/BLE, PSRAM, native USB).
• Display: Good Display GDEY0426T82-FL01C — 4.26" 800×480 E-Paper, controller SSD1677, 4-wire SPI, 24-pin FPC, with an integrated dual frontlight (5+5 series white LEDs, VF≤15 V, IF≤15 mA).
• Power: MCP73831 charger, discrete USB-priority load-share, AP2112K-3.3 LDO; 2× TPS61165 frontlight boost drivers.
• EDA: KiCad 8. CI: GitHub Actions (kicad-cli ERC/DRC/export).

Status & milestones

v0.1 — design captured; reviewable schematic in ereader-schematic.md; native Eeschema .kicad_sch + routed PCB not yet drawn in KiCad.

• Architecture, power tree, net list, pin map — ereader-pcb-design.md + ereader-connection-list.md
• Decisions recorded — docs/adr/0001–0005
• KiCad board ereader.* placed + config that opens cleanly
• BOM + SKiDL netlist generator
• CI: kicad-cli ERC/DRC/export workflow
• [~] Schematic — reviewable subsystem diagrams in ereader-schematic.md; native Eeschema capture + ERC clean pending
• PCB placed, routed + DRC clean
• Prototype built + brought up

Live verification state: the milestone checklist above.

Key decisions

Getting started

# Open the board in KiCad 8
kicad ereader.kicad_pro

# Read the electrical design (source of truth)
less ereader-connection-list.md

See docs/runbook.md for capture, verification, CI, fabrication, and bring-up. Component-level detail lives in ereader-pcb-design.md and ereader-schematic.md.

Repository layout

README.md              This Brief
CHANGELOG.md           Project history
ereader.*              The KiCad board (project, PCB, netlist, cmp)
ereader-*.md           Electrical source of truth: connection-list, schematic, pcb-design, footprints, README
ereader.pretty/        Project footprints (side tactile, ALPS SLLB5 lever)
ereader.3dshapes/      Simple 3D bodies for the project footprints
fp-lib-table           Registers the ereader.pretty footprint library
fab.py                 Gerber/drill export helper (preflight-gated)
gen_netlist.py         SKiDL netlist generator (real symbols → clean import)
preflight.py           Board↔netlist parity check (CI gate; fab.py guard)
docs/
  adr/                 Decisions (0001–0008 + template)
  research-log.md      Dated exploration notes
  runbook.md           Capture / verify / fabricate / bring-up
templates/             Colophon document templates (for ongoing use)
.github/workflows/     CI (KiCad ERC/DRC/export)

License

MIT for code, hardware, and documentation. (This repository started from the Colophon template; the doc method is reused under MIT here — the template's separate CC BY methodology license has been removed.)