SF32 E-Paper EPUB Reader¶

What Is EPD Reader?¶

OpenSiFli EPD Reader adapts atomic14/diy-esp32-epub-reader to SiFli SF32-OED-EPD hardware. It uses SF32LB52X as the processing core, reads EPUB files from the built-in file system or a TF card, lays out content through ZIP/XML/XHTML parsing, FreeType fonts, and image decoders, then drives an e-paper panel with full- and partial-refresh waveforms.

The current application provides library, table-of-contents, reading, reading-settings, function-settings, welcome/screen-off, low-battery, charging, and shutdown pages. It supports keys and touch, Chinese and English text, dynamic TTF/OTF fonts, font size/weight, line spacing, margins, and persistence of reading settings to the TF card. To conserve resources, the bundled Chinese font does not enable separate bold/italic faces by default; validate the actual result of weight options with the target font. It is a complete reference for a low-refresh reading terminal, not proof of general EPUB conformance or a production e-reader.

Why the SF32 Implementation?¶

This path combines SF32LB52 external storage, EPIC/LCDC display acceleration, touch, keys, Bluetooth PAN configuration, battery monitoring, and low-power management in one application. For a product team, its value is not merely showing one page: it enables joint evaluation of layout memory, full/partial refresh ghosting, waveform adaptation, TF-card power management, font access, interaction flow, and sleep behavior on supported hardware.

Upstream publishes no authoritative purchase link for the SF32-OED-EPD boards or panels, and it specifies no EPUB coverage rate, panel operating-temperature range, production lifetime, or current figures for each mode. This page therefore treats hardware revision, panel/touch combination, and software commit as a mandatory engineering baseline. Other e-paper modules are not drop-in substitutes.

Outcome, Scope, and Entry Criteria¶

Outcome: on a pinned SF32-OED-EPD_V1.1 board and 6.0-inch YZC085 V1.05 panel, reproduce build/download, library/contents/reading, key/touch input, settings persistence, full/partial refresh, low-battery, sleep, and shutdown behavior, then retain the evidence required for a product decision.

Out of scope: this page does not prove complete EPUB/CSS/font compatibility, DRM support, arbitrary-panel waveform compatibility, commercial reading quality, wireless content distribution, certification, or production reliability. Current source enables Bluetooth/PAN configuration and status UI, but the official README does not define network download as part of the local EPUB reading baseline.

Entry criteria: the team can build and download SiFli-SDK applications and can identify the board revision, panel model, flex orientation, battery polarity, and TF-card file system. If the board/panel source and hardware documentation are unclear, stop purchase commitment until SiFli or the hardware provider confirms them.

Hardware and Software Specifications¶

Hardware Specification¶

Software Specification¶

Choose a Supported Baseline¶

Use SF32-OED-EPD V1.1 + YZC085 V1.05 + FT5446U for the first reproduction. Upstream documents an explicit sf32-oed-epd_v11 build/download path, and Kconfig makes this the V1.1 default combination. Pin top-level commit 7d72223 and SDK submodule 8a1eb8a; do not change board, panel, touch controller, and waveform together in the first pass.

git clone --recursive https://github.com/OpenSiFli/EPD_Reader.git
cd EPD_Reader/epdiy-epub/project
scons --board=sf32-oed-epd_v11 --board_search_path=.. -j8

The Windows download script is build_sf32-oed-epd_v11_hcpu\uart_download.bat. Run it and enter the COM port when prompted. Inspect options with:

scons --board=sf32-oed-epd_v11 --board_search_path=.. --menuconfig

Delivery Map¶

System Architecture and Dependencies¶

flowchart LR
    FS["Built-in Flash file system"] --> EL["EPUB list / ZIP / XML / XHTML"]
    SD["TF card: EPUB, fonts, settings.cfg"] --> EL
    SD --> FM["FreeType font manager"]
    EL --> LO["Pagination and reading state"]
    FM --> LO
    IM["PNG / JPEG decoding"] --> LO
    BTN["Keys"] --> UI["UI state machine"]
    TP["FT5446U touch"] --> UI
    UI --> LO
    LO --> FB["1 bpp / 4 bpp framebuffer"]
    FB --> EPD["EPIC/LCDC + full/partial waveforms"]
    EPD --> PANEL["YZC085 1032 × 758 e-paper"]
    BAT["Battery ADC / charging / timeout policy"] --> UI
    UI --> PM["TF-card sleep / welcome page / shutdown"]

The main failure domains are content archive/XHTML parsing, font files and memory, TF-card detection/power, touch/key mapping, panel model/waveform/VCOM, full/partial ghosting, battery ADC/charge state, and shutdown/wake. Bluetooth PAN exists in current configuration but should not obscure local-file, display, and power baseline failures.

Stage 1 — Pin the Physical and Source Baseline¶

Goal: prove that board, panel, touch controller, and source describe one supported combination.

1. Record V1.1 board markings, the SF32 device, panel model, touch controller, flex orientation, and power source.
2. Pin the top-level commit and SDK submodule and retain complete submodule status.
3. Build and download from a clean environment; hash every generated image and download script.

Evidence to retain: physical photos, component identifiers, Git state, configuration, build/download logs, image hashes, and startup log.

Gate 1 exit criterion: the assembly matches the sf32-oed-epd_v11 default combination, and pinned inputs reproducibly generate and start the same image.

Stage 2 — Validate the Untouched Reading Flow¶

Goal: prove the core user journey before modification.

1. Discover EPUB files from built-in storage and TF card separately; firmware gives the TF card priority.
2. Complete Home → Library → Contents → Reading, verifying four library items per page, six contents items per page, and key/touch “select, then confirm” behavior.
3. Validate left/right page turns, the swipe-up overlay, -5/-1/+1/+5 jumps, contents/library return, and reading-settings entry.
4. Check Chinese, English, PNG/JPEG, and chapter navigation, recording unsupported or malformed content structures.

Evidence to retain: source/hash of test EPUBs, page photos, interaction timeline, logs, memory headroom, and classified failures.

Gate 2 exit criterion: the main flow repeats across the target sample set and every failure is classified as content, font, storage, memory, input, or display—not “intermittent.”

Stage 3 — Qualify Settings, Storage, and Recovery¶

Goal: ensure that real content and settings cannot leave the user in an unrecoverable state after storage events.

1. Place .ttf/.otf files in TF /fonts; validate discovery of up to 64 external fonts, selection, and fallback when a font disappears.
2. Test font sizes 24–48 px, font weight, 1.0×–2.0× line spacing, 5–20 px margins, and reboot persistence through /settings.cfg.
3. At safe non-write points, test no card, removal, reinsertion, corrupt settings, and unavailable fonts; do not hot-remove in a way that intentionally corrupts the file system.
4. Verify the current boundary: Continue Reading retains the most recently opened book index and chapter during the current run; do not describe it as complete reading-progress synchronization across reboots.

Evidence to retain: card specification/format, asset manifest, settings file, reboot results, error logs, and recovery actions.

Gate 3 exit criterion: target content and settings load repeatedly; missing card, invalid configuration, and missing font have comprehensible fallbacks that do not prevent return to Home.

Stage 4 — Qualify E-Paper Quality and Power¶

Goal: decide whether the panel driver and low-power policy fit the intended reading experience.

1. Validate full-refresh periods 5, 10, 20, and every time (0), recording ghosting, flashing, refresh time, and page consistency.
2. Validate the target panel's waveform, VCOM, and timing over the expected temperature range; do not copy values from another panel configuration.
3. Validate user timeout choices of 5/10/30 minutes, 1 hour, and never, plus the independent default policy that enters the shutdown page after five hours without interaction in the main loop.
4. Validate the status-bar battery percentage and charging-bolt icon, including removal of the charge icon at 98%; measure current for pagination, partial refresh, full refresh, idle, TF-card wake/sleep, low battery, charging, and shutdown paths.

Evidence to retain: panel/waveform version, temperature, page images, refresh statistics, current traces, battery conditions, and wake/shutdown results.

Gate 4 exit criterion: display quality, refresh latency, temperature, power, and recovery thresholds are defined and met, with an explicit disposition for every miss.

Stage 5 — Make a Controlled Adaptation and Review Readiness¶

Goal: prove that the team can adapt one boundary without breaking the baseline.

Suitable changes include adding one licensed font, adjusting one page, implementing one bounded EPUB-compatibility fix, or adding a separate driver for one new panel. New-panel work must cover Kconfig, resolution/DPI, touch, bus, waveform, temperature bands, LUT, timing, and VCOM while preserving the original board target for regression.

The product review must answer at least:

• What compatibility rate and memory ceiling apply to the target EPUB/XHTML/CSS/image/language corpus?
• Who controls and specifies panel supply, waveform, VCOM, temperature range, and lifetime?
• How do licenses for content, fonts, the main application, and every third-party library permit distribution?
• How does the device recover from TF-card corruption, settings corruption, low battery, abnormal shutdown, corrupted firmware, and interrupted update?
• If Bluetooth/PAN enters scope, how are its purpose, pairing, security, privacy, and radio compliance defined?
• How will production test cover display defects/ghosting, touch, keys, storage, battery ADC, charging, and sleep current?

Evidence to retain: change review, diff, regression matrix, risk register, owners, and product decision.

Gate 5 exit criterion: the controlled change passes every applicable regression, and remaining content, display, power, security, licensing, supply, and regulatory risks have owners, mitigations, and a proceed, defer, or stop decision.

Handoff to Product Design¶

The handoff package should include board/panel/touch revisions, pinned code and SDK, memory/partitions, file systems, font/content assets, waveform/VCOM/timing, full/partial-refresh policy, input map, battery curve, power measurements, fault recovery, license manifest, and production-test plan. Use the SF32LB52x integration path to select the chip, module, board, hardware design guide, and checklist, then redesign custom hardware from the qualified functional boundary.

Authoritative Sources¶

• OpenSiFli/EPD_Reader
• Project review commit 7d72223
• Official Chinese EPD Reader README
• Pinned SiFli-SDK submodule commit 8a1eb8a
• EPD Reader board/panel Kconfig
• EPD Reader V1.1 board configuration
• EPD Reader main-application MIT license
• atomic14/diy-esp32-epub-reader
• SiFli SF32LB52x build and download guide