SegLCDLib

Arduino library for segment LCD displays. Provides abstract interface, controller drivers (PCF85134/PCF85176/HT1621/HT1622/VK0192), and implementations for common displays.

Development Status

Versions 0.0.x are alpha/prerelease builds. API and behavior may change at any time, including breaking changes without semantic-versioning major bumps.

Quick Start

#include "SegLCD_HT1621_4SegDegree.h"

SegTransport3WireArduino transport(6, 5);  // DATA, WR pins
SegLCD_HT1621_4SegDegree lcd(transport, 7);  // CS pin

void setup() {
    lcd.init();
}

void loop() {
    lcd.setCursor(0, 0);
    lcd.print(25);        // Display: 25
    delay(1000);
}

Documentation

• Getting Started: Installation, first project, LCD selection
• Migration Guide: Version upgrade notes and required code changes
• Supported LCDs: Complete catalog with pinout and examples
• Architecture: Class hierarchy and design patterns
• Controllers: Protocol details (I2C, 3-wire serial)
• Adding New LCD: Tutorial for custom displays
• API Reference: Full Doxygen documentation

Supported Controllers

Controller	Protocol	Pins	Max Digits
PCF85134	I2C	2	display-dependent
PCF85176	I2C	2	13
PCF8576	I2C	2	13
HT1621	3-wire	3	6
HT1622	3-wire	3	10+
VK0192	3-wire	3	5

Featured Displays

See Supported LCDs for full catalog.

Display	Controller	Features
Xygax SEG_I2C	PCF85134	6-position SEG_I2C board
Temperature/Humidity	PCF85176	6-digit, icons
6-Digit Signal/Battery	PCF85176	Signal bars, battery, progress
2x4-Digit Sig/Bat/Power	PCF85176	2 rows, signal, battery, power
4-Digit with Degree	HT1621	Colon, degree symbol
6-Digit with Battery	HT1621	Battery indicator
LCM0844	HT1621	8 digits, labels, battery/load
LCM88128	HT1621	8 digits, labels, battery/load/PV
LCM59011	HT1621	4 digits, colon, wifi, battery, symbols
10-Digit 16-Segment	HT1622	Enhanced segments
5-Digit Signal/Battery	VK0192	Signal/battery/progress indicators

Installation

Arduino Library Manager

1. Sketch → Include Library → Manage Libraries
2. Search SegLCDLib
3. Click Install

Manual

1. Download: https://github.com/petrkr/SegLCDLib
2. Copy to Arduino/libraries/SegLCDLib
3. Restart Arduino IDE

Examples

21 complete examples in examples/ directory:

• PCF85134: 2 examples (RawLCD, XygaxSegI2C)
• PCF85176: 7 examples (RawLCD, TempHum, 2Row4DigSigBatPwr, etc.)
• HT1621: 6 examples (4DigDeg, 6DigBat, LCM0844, LCM59011, LCM88128, RawLCD)
• HT1622: 2 examples (10Digit16Segment, RawLCD)
• VK0192: 2 examples (5DigSigBatProg, RawLCD)
• PCF8576: 1 example (4Seg6SegMaintSegBatUnits)
• MenuControl: 1 example (pluginable menu system for ESP32)

Features

• Abstract Interface: Consistent LCD API 1.0 (Arduino LCD standard)
• Multiple Protocols: I2C (PCF85134/PCF85176) and 3-wire serial (HT1621/1622/VK0192)
• RAM Efficient: Buffered writes, minimal memory overhead
• Print Compatibility: Inherits from Print class for print()/println()
• Flexible: Easy to add support for new displays

Architecture

Application Code
    ↓
SegLCDLib Base (LCD API 1.0)
    ↓
Controller Driver (PCF85176, HT1621, etc.)
    ↓
LCD Implementation (display-specific)
    ↓
Hardware (I2C / 3-wire serial)

See Architecture for details.

Support

• Issues: https://github.com/petrkr/SegLCDLib/issues
• Documentation: https://petrkr.github.io/SegLCDLib/
• Reference: https://playground.arduino.cc/Code/LCDAPI/