MicroReader

A minimal EPUB/TXT reader for ESP32-C3 e-ink devices.

Features

• Antialiased font rendering
• TXT file reader with advanced text layout
• File browser for SD card navigation
• EPUB reader

Next Steps

• Bold/Italic Font support
• EPUB support
• Hyphenation for better text justification

Hardware

• Board: ESP32-C3 (QFN32) revision v0.4
• Chip: ESP32-C3 (RISC-V @ 160MHz)
• MAC Address: 9c:13:9e:64:a6:c4
• RAM: 400KB SRAM
• Flash: 16MB
• Display: 4.26" E-Ink GDEQ0426T82 (800×480px, SSD1677 controller)
  • Custom SPI pins: SCLK=8, MOSI=10, CS=21, DC=4, RST=5, BUSY=6
  • Supports B&W and 4-level grayscale modes
• Storage: SD Card
• Features: WiFi, BLE

Building

# Build
platformio run

# Upload
platformio run -t upload

# Monitor
platformio device monitor

Firmware Backup & Restore

Backup Original Firmware

Before flashing custom firmware, back up the factory firmware:

# Read entire 16MB flash
python -m esptool --chip esp32c3 --port COM5 read_flash 0x0 0x1000000 firmware_backup.bin

# Read only app0 (faster)
python -m esptool --chip esp32c3 --port COM5 read_flash 0x10000 0x640000 app0_backup.bin

Restore Original Firmware

To restore the backed-up firmware:

# Write back the entire flash
python -m esptool --chip esp32c3 --port COM5 write_flash 0x0 firmware_backup.bin

# Write back only app0 (faster)
python -m esptool --chip esp32c3 --port COM5 write_flash 0x10000 app0_backup.bin

Important: Make sure to use the correct COM port for your device.

Switching Boot Partitions (app0/app1)

# Backup current OTA data first
python -m esptool --port COM4 read_flash 0xE000 0x2000 otadata_backup.bin

# Flash to switch boot partition
# Boot app0
python -m esptool --port COM4 write_flash 0xE000 otadata_boot_app0.bin

# Boot app1
python -m esptool --port COM4 write_flash 0xE000 otadata_boot_app1.bin

Testing Text Layout on Windows

The project includes a test suite for validating text layout, word providers, and rendering:

Available Tests:

• StringWordProviderBidirectionalTest - Validates bidirectional text tokenization
• GreedyLayoutBidirectionalParagraphTest - Tests greedy line breaking with bidirectional navigation
• TextLayoutPageRenderTest - Full page rendering and pagination tests

Utility Scripts

Font Generation

scripts/generate_simplefont/ - Generate grayscale font headers from TrueType fonts

• CLI tool with character subset support
• GUI for glyph preview
• Generates bitmap preview images

# Install dependencies first
python -m pip install -r scripts/generate_simplefont/requirements.txt

# Generate font header
python -m scripts.generate_simplefont.cli --name Font14 --size 16 --chars-file .\data\chars_input.txt --out src/resources/fonts/Font14.h --ttf .\data\YourFont.ttf

# Preview glyphs with GUI
python scripts/generate_simplefont/gui.py

Image Conversion

scripts/simple_convert_image.py - Convert images to C++ byte arrays for display

• Supports 1-bit (B&W) and 2-bit (4-level grayscale) output
• Generates .h header files

LUT Editor

scripts/lut_editor.py - Visual editor for e-ink display waveform lookup tables

• Edit voltage patterns and timing groups
• Configure display refresh settings

Character Extraction

scripts/extract_chars.py - Extract unique characters from text files for font generation