HARDWARE

A small reader, built around known parts.

ENKU uses a ready ESP32-S3 + 3.97″ e-paper platform for reference validation while a dedicated portrait-first ENKU mainboard is developed in parallel. The goal is a reproducible open hardware platform that can support DIY builds, small batches and future kits without hiding the engineering record.

REFERENCE BOARD

Waveshare ESP32-S3 ePaper 3.97″

DISPLAY

800 × 480 · monochrome E Ink

CUSTOM MAINBOARD

R0.1 · portrait-first · in design

REFERENCE PLATFORM

The hardware baseline.

The Waveshare board remains the reference platform for firmware and electrical bring-up, but ENKU is no longer limited to a development board. A dedicated portrait-first mainboard is now being designed to improve ergonomics, reduce small-batch cost, integrate physical controls and sensors, and create a clean path toward reproducible kits.

MCUESP32-S3Application, storage, rendering and connectivity.

DISPLAY3.97″ · 800 × 480SSD1677-family monochrome e-paper path.

INPUTPhysical controlsUp / Function / Down + BOOT; no touchscreen dependency.

STORAGEmicroSDLocal books and persistent device data.

CONNECTIVITYWi‑Fi · BLEWi‑Fi used for local management; reading remains offline-capable.

POWERAXP2101 + Li‑PoCharging, telemetry and PMU-assisted power states.

VERIFICATION

Known versus measured.

ENKU separates vendor/source-confirmed implementation details from things that only become facts after measurement. That distinction matters especially for e-paper refresh behavior, sleep current, charging and mechanical fit.

SOURCE-VERIFIED

Control mapping

Current official source maps Up → GPIO4, Function → GPIO5, Down → GPIO6 and BOOT → GPIO0. ENKU keeps those raw pins below its logical input layer.

SOURCE-VERIFIED

Display interface

The ESP-IDF target uses the vendor-aligned SSD1677 path with BUSY, DC, CS, SCLK, MOSI and RST already represented in the platform layer.

SOURCE-VERIFIED

Power architecture

AXP2101 PMU behavior, panel sleep and full PMU shutdown are modeled as distinct states. Display sleep is not treated as system sleep.

PHYSICAL TEST

Refresh quality

Full, fast and partial refresh code exists, but timing, orientation, ghosting and escalation thresholds must be observed on the real panel.

PHYSICAL TEST

Battery & sleep

Final battery size, charge behavior, practical runtime, suspend current and wake semantics remain deliberately unclaimed until measured.

PHYSICAL TEST

Mechanical envelope

The enclosure starts from real measurements of the board, display stack, buttons, connectors and battery — not from catalog dimensions alone.

CUSTOM HARDWARE

From reference board to an ENKU mainboard.

The custom board is being designed around the actual reader UX: portrait orientation, bottom-center USB-C, a real hard power switch, right-side page controls, BMI270 motion/orientation sensing, Hall-cover wake and population options for future frontlight hardware.

BASEOne core PCBESP32-S3, e-paper, microSD, USB-C, battery, buttons, BMI270 and service pads.

DOCKMagnetic pogo optionReserved low-profile secondary 5 V charging interface for a stand or cable accessory.

PROWireless-readyCoil/receiver space can be reserved without forcing wireless-charging cost into every Base unit.

OPEN HARDWAREReproducible BOMDesign files, assembly data and bring-up notes are intended to stay public and versioned.

KITSFuture small batchesPossible electronics, Base, Cover and Pro kits after hardware validation.

STATUSEngineering in progressKit availability is a roadmap item, not a current product claim.

CHARGING

USB-C first, optional dock and wireless power.

USB-C remains the universal charge/data connection. ENKU also reserves room for lower-friction charging options where they make sense, while keeping Base cost under control.

PRIMARY

USB-C

Bottom-center USB-C stays standard across the enclosure family for charging, flashing and service.

OPTION

Magnetic pogo dock

A keyed four-contact charging interface is being considered for a dock or magnetic cable. Its 5 V input would be isolated from USB VBUS before the charger stage.

PRO / DNP

Wireless charging

Wireless charging is treated as a Pro or optional population feature. Coil position, shielding, heat and certification need physical validation before it can be called a finished feature.

ENKU DOCK

Charge it. Then let the screen keep working.

A separate ENKU Dock is planned as a low-cost pogo charging stand. Dock detection gives the reader a new low-refresh mode instead of treating the stand like an ordinary cable.

INTERFACE4-pin pogoProtected 5 V input, ground and explicit dock detection with asymmetric alignment.

DEFAULT VIEWClockMinute-resolution e-paper clock with refresh behavior tuned to control ghosting.

READINGBook dashboardCurrent cover, progress, battery and daily reading information can stay visible on the desk.

CUSTOMDashboard presetsLocal configurable blocks such as time, date, battery, cached weather and custom text.

FIRST DOCKPassive hardwareNo dock MCU required: pogo contacts, USB-C power input and mechanical/magnetic alignment.

SEPARATE OPTIONQi for ProWireless charging remains a different Pro/DNP path rather than making the simple dock expensive.

BOARD MAP

Current integration pins.

These values are implementation references from the current full-board/vendor baseline and are kept public so firmware and documentation can be checked against the same assumptions.

Area	Signal	GPIO / address
Display	BUSY / DC / CS / SCLK / MOSI / RST	3 / 9 / 10 / 11 / 12 / 46
SDMMC	CLK / CMD / D0 / D1 / D2 / D3	16 / 17 / 15 / 7 / 8 / 18
I²C	SDA / SCL	41 / 42
PMU	AXP2101	0x34
Buttons	Up / Function / Down / BOOT	4 / 5 / 6 / 0

DETAILS

The repository carries the engineering record.

The website shows the current readable hardware snapshot. Pin provenance, bring-up notes, power behavior and future measurements remain versioned with the firmware.

Hardware docs ↗ Project status →