A custom-built e-ink reading device based on the ESP32-C3, designed for everyday use. Built around a 4.2" e-ink display with a frontlight for reading in the dark environment, running a modified version of the Crosspoint open-source firmware adapted for custom hardware. The goal was to build a capable, low-cost alternative to commercial e-readers with full control over both hardware and software.
Note: This is a fork of Crosspoint Reader. See What's changed from upstream for a summary of hardware-specific modifications.
The hardware designs in /Hardware are licensed under the
CERN-OHL-W v2.
Building your own? See the Build guide for step-by-step assembly instructions.
| Component | Details |
|---|---|
| MCU | ESP32-C3 (4MB flash) |
| Display | Good Display 4.2" grayscale e-ink panel |
| Storage | SD card (books, cache, user settings) |
| Frontlight | TI TPS61169 PWM-controlled LED driver, 15V boost |
| Battery | 700mAh LiPo |
| USB | USB-C (charging + native USB via differential pair) |
| PCB | 4-layer, custom KiCad design (Rev. B) |
F.Cu — signal
GND — full ground plane
PWR — power distribution
B.Cu — signal
Ground pour with stitching vias on both outer layers. EMI-sensitive boost converter traces kept compact.
| Rail | Source | Purpose |
|---|---|---|
| 3.4–4.2V | LiPo battery | System input |
| 3.3V | LDO | ESP32-C3, logic |
| 5V | USB-C input | Charging |
| ±20V | Boost converter | E-ink panel driver |
| 15V | Boost converter (TPS61169) | Frontlight LED driver |
Three operating states optimized for battery life:
| State | Description | Wake latency |
|---|---|---|
| Active | Full speed, display updating | — |
| Sleep | Reduced CPU clock, peripherals idle | Fast |
| Deep sleep | µA range consumption, triggered by power button | Slow |
The device enters Sleep automatically after a display update completes. Deep sleep is only used when powered off via the power button.
| Button | Function |
|---|---|
| Left / Right / Back / Confirm | Context-sensitive navigation (current function shown on display) |
| Power button | Short press: page turn / Long press: power on/off |
Based on Crosspoint Reader with modifications for custom hardware and 4MB flash constraint.
- HalFrontlight — new HAL driver for PWM-controlled frontlight via TPS61169
- HalPowerManager — smaller tweaks
- HalGPIO — GPIO, button layout adapted to custom PCB
- partitions_4mb.csv — custom partition scheme to fit 4MB flash (replaces upstream 16MB default)
- platformio.ini — 4MB build configuration
- Display refresh — modified refresh handling for Good Display 4.2" panel compatibility
See docs/4mb-build/ for detailed documentation on the 4MB build process and known issues.
ESP32_E-Reader/
├── Hardware/
│ ├── 3D CAD/ — enclosure 3D models
│ ├── Bill Of Materials/ — BOM spreadsheets
│ ├── PCB/ — KiCad project (Rev. B)
│ ├── REV-A/ — Rev. A schematic/layout reference
│ └── LICENSE — CERN-OHL-W v2
├── Datasheets of Components/ — component datasheets (PDF)
└── Software/
└── crosspoint-reader/ — firmware (fork of Crosspoint Reader)
├── src/ — application source (activities, UI)
├── lib/ — internal libraries (Epub engine, GfxRenderer, HAL, I18n)
├── open-x4-sdk/ — Xteink X4 community SDK (submodule)
├── docs/ — build docs, file formats, 4mb-build notes
├── scripts/ — build/codegen/debugging scripts
├── test/ — unit tests
├── platformio.ini — build configuration
└── LICENSE — MIT
- PlatformIO
- ESP32-C3 board with 4MB flash
git clone https://github.com/IS7V4N/ESP32_E-Reader.git
cd ESP32_E-Reader
git submodule update --init --recursive
~/.platformio/penv/bin/pio run -e 4mb -t upload/Hardware are licensed under the
CERN-OHL-W v2.
Firmware modifications follow the license of the upstream Crosspoint Reader project.