Abstract base class for LCD segment display drivers. More...

#include <SegLCDLib.h>

Inheritance diagram for SegLCDLib:

Public Types
enum	BacklightMode { BACKLIGHT_DIGITAL , BACKLIGHT_PWM }
	Backlight mode for GPIO control. More...

Public Member Functions
virtual	~SegLCDLib ()
	Virtual destructor to ensure proper cleanup in derived classes.

virtual void	init ()=0
	Logical display sections that can be targeted by higher-level rendering logic.

virtual void	clear ()
	Clear all visible segments on the display.

void	home ()
	Set cursor to 0, 0 without clear display.

virtual void	setCursor (uint8_t row, uint8_t col)
	Set cursor on exact digit.

virtual size_t	write (uint8_t ch)

virtual void	command (uint8_t command)=0
	Send RAW command to controller.

virtual void	on ()=0
	Turn the display on.

virtual void	off ()=0
	Turn the display off.

void	initBacklight (int8_t backlightPin, BacklightMode backlightMode=BACKLIGHT_DIGITAL, bool backlightActiveHigh=true)
	Initialize GPIO backlight control.

virtual void	setBacklight (bool state)
	Set backlight state (on/off).

virtual void	setBacklight (int brightness)
	Set backlight brightness (0-255).

void	setAutoFlush (bool enable)
	Enable or disable autoflush mode.

bool	getAutoFlush () const
	Get current autoflush state.

virtual void	flush ()
	Flush all buffered changes to the display.

virtual void	flush (uint8_t startAddr, uint8_t length)
	Flush specific range of buffered changes to the display.

const uint8_t *	getRamBuffer () const
	Get pointer to internal RAM buffer (read-only).

size_t	getRamBufferSize () const
	Get size of internal RAM buffer in bytes.

Protected Member Functions
void	_setFlag (uint8_t mask)
	Set a specific flag bit.

void	_clearFlag (uint8_t mask)
	Clear a specific flag bit.

bool	_isFlagSet (uint8_t mask) const
	Check if a specific flag bit is set.

void	_clearAllFlags ()
	Clear all flags.

bool	_dotWrite (uint8_t ch, int8_t minCol, int8_t maxCol, int8_t ramOffset)
	Write decimal point.

void	_dotClearCur (int8_t minCol, int8_t maxCol)
	Clear current decimal (overwrite).

void	_colonClearIfNotFlagged (uint8_t ch, uint8_t colonCol, uint8_t colonFlag)
	Clear colon if its flag is not set.

virtual void	_setDecimal (uint8_t row, uint8_t col, bool state)
	Virtual method for setting decimal point.

virtual void	_setColon (uint8_t row, uint8_t col, bool state)
	Virtual method for setting colon.

void	_allocateBuffer (size_t size)
	Allocate RAM buffer for display data.

void	_writeRamMasked (uint8_t data, uint8_t address, uint8_t mask=0xFF)
	Write to display RAM with nibble-aware masking support.

virtual void	_writeRam (uint8_t data, uint8_t address)=0
	Low-level method to write a single byte to display RAM.

virtual void	_writeRam (uint8_t *data, size_t length, uint8_t address)=0
	Low-level method to write a data buffer to display RAM.

uint8_t	_get_char_value (char ch)
	Helper method to convert a character to its segment representation.

uint16_t	_get_16char_value (char ch)
	Helper method to convert a character to its 16-segment representation.

Protected Attributes
bool	_autoFlush = true
	Autoflush mode enabled flag (default: true for LCD API 1.0 compatibility).

int8_t	_backlightPin = -1
	Backlight GPIO pin (-1 if disabled)

BacklightMode	_backlightMode = BACKLIGHT_DIGITAL
	Backlight mode (DIGITAL or PWM)

bool	_backlightActiveHigh = true
	Backlight active high flag.

uint8_t	_backlightBrightness = 0
	Cached backlight brightness.

uint8_t	_displayFlags = 0
	LEDC channel for old ESP32 Arduino Core (2.0.x)

uint8_t *	_ramBuffer = nullptr
	Dynamic RAM buffer for display data (allocated by derived classes).

size_t	_ramBufferSize = 0
	Size of allocated RAM buffer in bytes.

uint8_t	_cursorRow = 0
	Current Row.

uint8_t	_cursorCol = 0
	Current Column.

Static Protected Attributes
static constexpr uint8_t	FLAG_PENDING_DOT = 0x80
	Common flag for decimal handling when RAM offset is 0.

Detailed Description

Abstract base class for LCD segment display drivers.

This class defines the generic interface required by all LCD segment drivers, including display control, character output, and data writing methods.

Member Enumeration Documentation

◆ BacklightMode

enum SegLCDLib::BacklightMode

Backlight mode for GPIO control.

Enumerator
BACKLIGHT_DIGITAL	Digital on/off mode.
BACKLIGHT_PWM	PWM brightness control (0-255)

Constructor & Destructor Documentation

◆ ~SegLCDLib()

SegLCDLib::~SegLCDLib ( )

virtual

Virtual destructor to ensure proper cleanup in derived classes.

Member Function Documentation

◆ _allocateBuffer()

void SegLCDLib::_allocateBuffer ( size_t size )

protected

Allocate RAM buffer for display data.

Parameters

size	Buffer size in bytes

◆ _clearAllFlags()

void SegLCDLib::_clearAllFlags ( )

protected

Clear all flags.

◆ _clearFlag()

void SegLCDLib::_clearFlag ( uint8_t mask )

protected

Clear a specific flag bit.

Parameters

mask	Bitmask with bit(s) to clear

◆ _colonClearIfNotFlagged()

void SegLCDLib::_colonClearIfNotFlagged	(	uint8_t	ch,
		uint8_t	colonCol,
		uint8_t	colonFlag
	)

protected

Clear colon if its flag is not set.

Internal helper for display-specific write() implementations.

Parameters

ch	Character being processed
colonCol	Colon position
colonFlag	Flag bit for this colon

◆ _dotClearCur()

void SegLCDLib::_dotClearCur	(	int8_t	minCol,
		int8_t	maxCol
	)

protected

Clear current decimal (overwrite).

Internal helper for display-specific write() implementations.

Parameters

minCol	Minimum valid column
maxCol	Maximum valid column

◆ _dotWrite()

bool SegLCDLib::_dotWrite	(	uint8_t	ch,
		int8_t	minCol,
		int8_t	maxCol,
		int8_t	ramOffset
	)

protected

Write decimal point.

Internal helper for display-specific write() implementations.

Parameters

ch	Character to process
minCol	Minimum valid column for decimal
maxCol	Maximum valid column for decimal
ramOffset	RAM offset for decimal (-1, 0, or +1)

Returns: true if character '.' was processed

◆ _get_16char_value()

uint16_t SegLCDLib::_get_16char_value ( char ch )

protected

Helper method to convert a character to its 16-segment representation.

◆ _get_char_value()

uint8_t SegLCDLib::_get_char_value ( char ch )

protected

Helper method to convert a character to its segment representation.

◆ _isFlagSet()

bool SegLCDLib::_isFlagSet ( uint8_t mask ) const

protected

Check if a specific flag bit is set.

Parameters

mask	Bitmask with bit(s) to check

Returns: true if all bits in mask are set

◆ _setColon()

virtual void SegLCDLib::_setColon	(	uint8_t	row,
		uint8_t	col,
		bool	state
	)

inlineprotectedvirtual

Virtual method for setting colon.

Default implementation is empty (no-op).

Reimplemented in SegLCD_HT1621_4SegDegree, SegLCD_HT1621_LCM59011, SegLCD_PCF85176_4DR821B, SegLCD_PCF85176_6DigitSignalBatteryProgress, SegLCD_PCF85176_T1T2Lcd, and SegLCD_PCF8576_4Seg6SegMaintSegBatUnits.

◆ _setDecimal()

virtual void SegLCDLib::_setDecimal	(	uint8_t	row,
		uint8_t	col,
		bool	state
	)

inlineprotectedvirtual

Virtual method for setting decimal point.

Each LCD has its own implementation with HW specifics. Default implementation is empty (no-op).

Reimplemented in SegLCD_HT1621_4SegDegree, SegLCD_HT1621_6SegBat, SegLCD_HT1621_LCM0844, SegLCD_HT1621_LCM88128, SegLCD_HT1622_10Dig16Seg, SegLCD_PCF85176_2Row4DigSigBatPwr, SegLCD_PCF85176_4DR821B, SegLCD_PCF85176_6DigitSignalBatteryProgress, SegLCD_PCF85176_OneDigit, SegLCD_PCF85176_T1T2Lcd, SegLCD_PCF85176_TempHumidity, SegLCD_PCF8576_4Seg6SegMaintSegBatUnits, and SegLCD_VK0192_5DigSigBattProgress.

◆ _setFlag()

void SegLCDLib::_setFlag ( uint8_t mask )

protected

Set a specific flag bit.

Parameters

mask	Bitmask with bit(s) to set

◆ _writeRam() [1/2]

virtual void SegLCDLib::_writeRam	(	uint8_t *	data,
		size_t	length,
		uint8_t	address
	)

protectedpure virtual

Low-level method to write a data buffer to display RAM.

Parameters

data	Pointer to data buffer
length	Length of data buffer
address	Start RAM address

Implemented in SegDriver_3Wire, SegDriver_HT1622, SegDriver_PCx85, and SegDriver_VK0192.

◆ _writeRam() [2/2]

virtual void SegLCDLib::_writeRam	(	uint8_t	data,
		uint8_t	address
	)

protectedpure virtual

Low-level method to write a single byte to display RAM.

Parameters

data	Data byte
address	RAM address

Implemented in SegDriver_3Wire, SegDriver_HT1622, SegDriver_VK0192, and SegDriver_PCx85.

◆ _writeRamMasked()

void SegLCDLib::_writeRamMasked	(	uint8_t	data,
		uint8_t	address,
		uint8_t	mask = `0xFF`
	)

protected

Write to display RAM with nibble-aware masking support.

Handles both byte-aligned and nibble-aligned addresses with read-modify-write when mask is not 0xFF. Updates internal buffer and writes to hardware.

Parameters

data	Value to write
address	RAM address (nibble-level addressing)
mask	Bitmask for selective bit updates (0xFF = write all bits)

◆ clear()

void SegLCDLib::clear ( )

virtual

Clear all visible segments on the display.

Reimplemented in SegDriver_HT1621, SegDriver_HT1622, SegDriver_PCx85, SegDriver_VK0192, SegLCD_HT1621_4SegDegree, SegLCD_PCF85176_TempHumidity, and SegLCD_PCF8576_4Seg6SegMaintSegBatUnits.

◆ command()

virtual void SegLCDLib::command ( uint8_t command )

pure virtual

Send RAW command to controller.

Parameters

command Raw command byte

Implemented in SegDriver_3Wire, and SegDriver_PCx85.

◆ flush() [1/2]

void SegLCDLib::flush ( )

virtual

Flush all buffered changes to the display.

Writes the entire display buffer to the hardware. This is useful when autoflush is disabled to batch multiple write() calls into a single hardware update cycle.

Safe to call even when autoflush is enabled (no effect).

See also: setAutoFlush()

Reimplemented in SegDriver_HT1621, SegDriver_HT1622, SegDriver_PCx85, and SegDriver_VK0192.

◆ flush() [2/2]

void SegLCDLib::flush	(	uint8_t	startAddr,
		uint8_t	length
	)

virtual

Flush specific range of buffered changes to the display.

Writes a specific address range from the display buffer to hardware. This is an advanced API for optimizing updates when only part of the display needs to be refreshed.

For example, to update only the first row of a multi-row display:

lcd.flush(0, 6); // Update first 6 bytes (row 0)

Safe to call even when autoflush is enabled (no effect).

Parameters

startAddr	Starting buffer address in bytes (RAM buffer index)
length	Number of bytes to flush

See also: setAutoFlush()

Reimplemented in SegDriver_HT1621, SegDriver_HT1622, SegDriver_PCx85, SegDriver_VK0192, SegDriver_HT1621, SegDriver_HT1622, SegDriver_PCx85, and SegDriver_VK0192.

◆ getAutoFlush()

bool SegLCDLib::getAutoFlush ( ) const

Get current autoflush state.

Returns: true if autoflush is enabled, false if in manual flush mode

◆ getRamBuffer()

const uint8_t * SegLCDLib::getRamBuffer ( ) const

Get pointer to internal RAM buffer (read-only).

Returns: Pointer to RAM buffer or nullptr if not allocated.

◆ getRamBufferSize()

size_t SegLCDLib::getRamBufferSize ( ) const

Get size of internal RAM buffer in bytes.

Returns: Buffer size in bytes (0 if not allocated).

◆ home()

void SegLCDLib::home ( )

Set cursor to 0, 0 without clear display.

◆ init()

virtual void SegLCDLib::init ( )

pure virtual

Logical display sections that can be targeted by higher-level rendering logic.

Initialize the display driver, clear display and set position to 0,0.

Implemented in SegDriver_3Wire, SegDriver_PCx85, SegLCD_HT1621_4SegDegree, SegLCD_HT1621_6SegBat, SegLCD_HT1621_LCM0844, SegLCD_HT1621_LCM59011, SegLCD_HT1621_LCM88128, SegLCD_HT1622_10Dig16Seg, SegLCD_PCF85176_2Row4DigSigBatPwr, SegLCD_PCF85176_4DR821B, SegLCD_PCF85176_6DigitSignalBatteryProgress, SegLCD_PCF85176_OneDigit, SegLCD_PCF85176_T1T2Lcd, SegLCD_PCF85176_TempHumidity, SegLCD_PCF8576_4Seg6SegMaintSegBatUnits, and SegLCD_VK0192_5DigSigBattProgress.

◆ initBacklight()

void SegLCDLib::initBacklight	(	int8_t	backlightPin,
		BacklightMode	backlightMode = `BACKLIGHT_DIGITAL`,
		bool	backlightActiveHigh = `true`
	)

Initialize GPIO backlight control.

Must be called from init() of concrete implementations to setup the backlight GPIO.

Parameters

backlightPin	GPIO pin for backlight control (-1 to disable)
backlightMode	Backlight mode (DIGITAL or PWM)
backlightActiveHigh	true if backlight is active high (default), false for active low

◆ off()

virtual void SegLCDLib::off ( )

pure virtual

Turn the display off.

Implemented in SegDriver_3Wire, and SegDriver_PCx85.

◆ on()

virtual void SegLCDLib::on ( )

pure virtual

Turn the display on.

Implemented in SegDriver_3Wire, and SegDriver_PCx85.

◆ setAutoFlush()

void SegLCDLib::setAutoFlush ( bool enable )

Enable or disable autoflush mode.

In autoflush mode (default), each write() call immediately updates the display. This maintains LCD API 1.0 compatibility but can cause flicker when multiple segments are updated rapidly (e.g., writing "123.4" causes decimal point to flicker).

In manual flush mode, write() only updates the internal buffer. Call flush() to write all buffered changes to the display at once, eliminating flicker.

Example usage:

// Disable autoflush for rapid updates
lcd.setAutoFlush(false);
 
void loop() {
    lcd.setCursor(0, 0);
    lcd.print(value);  // Buffer only, no HW write
    lcd.flush();       // Single HW write of all changes
    delay(100);
}

Parameters

enable true to enable autoflush (default), false for manual flush mode

See also: flush()

◆ setBacklight() [1/2]

void SegLCDLib::setBacklight ( bool state )

virtual

Set backlight state (on/off).

Parameters

state true to turn backlight on, false to turn off

◆ setBacklight() [2/2]

void SegLCDLib::setBacklight ( int brightness )

virtual

Set backlight brightness (0-255).

Parameters

brightness Brightness level 0-255, where 0 is off and 255 is full brightness

◆ setCursor()

void SegLCDLib::setCursor	(	uint8_t	row,
		uint8_t	col
	)

virtual

Set cursor on exact digit.

Because LCD API is mainly used for character displays in this segment displays this function will be littlebit confusing. Because most of Segment LCD has only one row, thus this will be like row 0 and column will represent actual digit.

But if there is LCD like T1T2 LCD. Row 0 will be clock part, Row 1 will be T1: part and Row 2 will be T2: part of LCD

Parameters

row	Row, where 0-MAXROWS
col	Column 0-MAXDIGITS in current row

Reimplemented in SegLCD_HT1621_4SegDegree, SegLCD_PCF85176_4DR821B, SegLCD_PCF85176_6DigitSignalBatteryProgress, SegLCD_PCF85176_T1T2Lcd, SegLCD_PCF85176_TempHumidity, SegLCD_PCF8576_4Seg6SegMaintSegBatUnits, and SegLCD_VK0192_5DigSigBattProgress.

◆ write()

virtual size_t SegLCDLib::write ( uint8_t ch )

inlinevirtual

Reimplemented in SegLCD_HT1621_4SegDegree, SegLCD_HT1621_6SegBat, SegLCD_HT1621_LCM0844, SegLCD_HT1621_LCM59011, SegLCD_HT1621_LCM88128, SegLCD_HT1622_10Dig16Seg, SegLCD_PCF85176_2Row4DigSigBatPwr, SegLCD_PCF85176_4DR821B, SegLCD_PCF85176_6DigitSignalBatteryProgress, SegLCD_PCF85176_OneDigit, SegLCD_PCF85176_T1T2Lcd, SegLCD_PCF85176_TempHumidity, SegLCD_PCF8576_4Seg6SegMaintSegBatUnits, SegLCD_PCx85_Raw, and SegLCD_VK0192_5DigSigBattProgress.

Field Documentation

◆ _autoFlush

bool SegLCDLib::_autoFlush = true

protected

Autoflush mode enabled flag (default: true for LCD API 1.0 compatibility).

◆ _backlightActiveHigh

bool SegLCDLib::_backlightActiveHigh = true

protected

Backlight active high flag.

◆ _backlightBrightness

uint8_t SegLCDLib::_backlightBrightness = 0

protected

Cached backlight brightness.

◆ _backlightMode

BacklightMode SegLCDLib::_backlightMode = BACKLIGHT_DIGITAL

protected

Backlight mode (DIGITAL or PWM)

◆ _backlightPin

int8_t SegLCDLib::_backlightPin = -1

protected

Backlight GPIO pin (-1 if disabled)

◆ _cursorCol

uint8_t SegLCDLib::_cursorCol = 0

protected

Current Column.

◆ _cursorRow

uint8_t SegLCDLib::_cursorRow = 0

protected

Current Row.

◆ _displayFlags

uint8_t SegLCDLib::_displayFlags = 0

protected

LEDC channel for old ESP32 Arduino Core (2.0.x)

Generic flag storage for display-specific state tracking.

Individual LCD implementations can use these bits to track state like:

Colon positions active
Previous dot written
Special characters displayed

Usage: Define bit constants in derived class, use helper methods to set/clear/check.

◆ _ramBuffer

uint8_t* SegLCDLib::_ramBuffer = nullptr

protected

Dynamic RAM buffer for display data (allocated by derived classes).

◆ _ramBufferSize

size_t SegLCDLib::_ramBufferSize = 0

protected

Size of allocated RAM buffer in bytes.

◆ FLAG_PENDING_DOT

constexpr uint8_t SegLCDLib::FLAG_PENDING_DOT = 0x80

staticconstexprprotected

Common flag for decimal handling when RAM offset is 0.

Used when decimal point shares the same RAM byte as the digit. Set when '.' is written, cleared after next character preserves it.

The documentation for this class was generated from the following files:

src/SegLCDLib.h
src/SegLCDLib.cpp

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ BacklightMode

Constructor & Destructor Documentation

◆ ~SegLCDLib()

Member Function Documentation

◆ _allocateBuffer()

◆ _clearAllFlags()

◆ _clearFlag()

◆ _colonClearIfNotFlagged()

◆ _dotClearCur()

◆ _dotWrite()

◆ _get_16char_value()

◆ _get_char_value()

◆ _isFlagSet()

◆ _setColon()

◆ _setDecimal()

◆ _setFlag()

◆ _writeRam() [1/2]

◆ _writeRam() [2/2]

◆ _writeRamMasked()

◆ clear()

◆ command()

◆ flush() [1/2]

◆ flush() [2/2]

◆ getAutoFlush()

◆ getRamBuffer()

◆ getRamBufferSize()

◆ home()

◆ init()

◆ initBacklight()

◆ off()

◆ on()

◆ setAutoFlush()

◆ setBacklight() [1/2]

◆ setBacklight() [2/2]

◆ setCursor()

◆ write()

Field Documentation

◆ _autoFlush

◆ _backlightActiveHigh

◆ _backlightBrightness

◆ _backlightMode

◆ _backlightPin

◆ _cursorCol

◆ _cursorRow

◆ _displayFlags

◆ _ramBuffer

◆ _ramBufferSize

◆ FLAG_PENDING_DOT