Controls multiple MAX7219/MAX7221 LED drivers via hardware SPI. More...

#include <SBK_MAX72xxHard.h>

Public Member Functions
	SBK_MAX72xxHard (uint8_t csPin, uint8_t devsNum=1)
	Construct a new hardware SPI SBK_MAX72xxHard driver instance.
void	setSPIClock (uint32_t frequency)
	Set SPI clock speed (hardware SPI only).
void	end ()
	Set SPI clock speed (hardware SPI only).
uint8_t	maxRows (uint8_t devIdx=0) const
	Returns the number of addressable row lines (anode outputs = SEGx).
uint8_t	maxColumns () const
	Returns the number of addressable columns (cathode outputs = DIGx).
uint8_t	maxSegments (uint8_t devIdx=0) const
	Returns the total number of addressable LED segments for this device.
void	begin ()
	Initialize SPI pins and all MAX72xx chips.
void	setShutdown (uint8_t devIdx, bool status)
	Enable or disable shutdown mode on a specific device.
void	setScanLimit (uint8_t devIdx, uint8_t limit)
	Set the scan limit (number of active digits) for a specific device.
void	setBrightness (uint8_t devIdx, uint8_t brightness)
	Set display brightness for a specific device.
uint8_t	devsNum () const
	Return the number of actives driver devices.
void	clear (uint8_t devIdx)
	Clear display buffer and hardware for one device.
void	clear ()
	Clear display buffers and hardware for all devices.
void	setLed (uint8_t devIdx, uint8_t rowIdx, uint8_t colIdx, bool state)
	Set the state of a specific LED in the device’s internal matrix buffer.
bool	getLed (uint8_t devIdx, uint8_t rowIdx, uint8_t colIdx) const
	Get the state of a specific LED in the device’s internal matrix buffer.
void	setCol (uint8_t devIdx, uint8_t colIdx, uint8_t value)
	Set the entire col value for a specific device (buffer only).
void	show ()
	Push the internal display buffer to all connected devices.
void	show (uint8_t devIdx)
	Push the internal display buffer to a specific device.

Detailed Description

Controls multiple MAX7219/MAX7221 LED drivers via hardware SPI.

Constructor & Destructor Documentation

◆ SBK_MAX72xxHard()

SBK_MAX72xxHard::SBK_MAX72xxHard	(	uint8_t	csPin,
		uint8_t	devsNum = 1 )

Construct a new hardware SPI SBK_MAX72xxHard driver instance.

Parameters

csPin	Chip Select (CS) pin used for SPI communication.
devsNum	Number of daisy-chained MAX72xx devices. Default is 1.

Initializes internal display buffer for each device in the chain. Each device reserves 8 bytes — one for each digit line (DIG0–DIG7), representing columns (cathode outputs).*

Note: Each byte in the buffer holds segment (SEG0–SEG7) values for one column.

Member Function Documentation

◆ clear()

void SBK_MAX72xxHard::clear ( uint8_t devIdx )

Clear display buffer and hardware for one device.

Parameters

devIdx Target device index.

◆ devsNum()

uint8_t SBK_MAX72xxHard::devsNum ( ) const

inline

Return the number of actives driver devices.

Returns: number of actives driver devices.

◆ end()

void SBK_MAX72xxHard::end ( )

Set SPI clock speed (hardware SPI only).

Parameters

frequency Frequency in Hz (e.g., 1000000 for 1 MHz).

◆ getLed()

bool SBK_MAX72xxHard::getLed	(	uint8_t	devIdx,
		uint8_t	rowIdx,
		uint8_t	colIdx ) const

Get the state of a specific LED in the device’s internal matrix buffer.

This function reads the last known state of a given LED at the specified row and column on a target device. It does not access the physical display hardware, but instead reads from the internal RAM buffer used for batching updates.

Note: This function may not reflect real-time display contents unless show() has been called after setLed(). For animations or state-dependent logic, ensure consistency by calling show() regularly.

Parameters

devIdx	Index of the target device (0-based).
rowIdx	Row index (0–7).
colIdx	Column index (0–7).

Returns: true if the LED is currently set ON in the buffer, false if OFF or invalid.

Note

The coordinate system follows a standard [row, col] layout. For MAX72xx drivers:

row corresponds to SEGx (segment outputs, V+ source = anode)
col corresponds to DIGx (digit selectors, GND sink = cathode)

◆ maxColumns()

uint8_t SBK_MAX72xxHard::maxColumns ( ) const

inline

Returns the number of addressable columns (cathode outputs = DIGx).

This is a fixed value of 8 for MAX7219/7221, since each digit line (DIG0–DIG7) selects one column (cathode). Each DIGx line maps to one 8-bit buffer entry representing the vertical SEGx lines.

Returns: Number of columns (DIGx = cathode outputs), always 8.

◆ maxRows()

uint8_t SBK_MAX72xxHard::maxRows ( uint8_t devIdx = 0 ) const

inline

Returns the number of addressable row lines (anode outputs = SEGx).

Parameters

devIdx Index of the target device (0-based in daisy chain). This parameter is ignored for MAX7219/7221 chips, but included for API compatibility with SBK_BarDrive.

For MAX7219/7221 drivers, this value is always 8, since each column (DIGx) can display up to 8 vertical segments connected to SEG0–SEG7 (anode lines).

Returns: Number of row lines (SEGx/anodes), always 8 for MAX72xx devices.

◆ maxSegments()

uint8_t SBK_MAX72xxHard::maxSegments ( uint8_t devIdx = 0 ) const

inline

Returns the total number of addressable LED segments for this device.

Parameters

devIdx Index of the target device (0-based in daisy chain). This parameter is ignored for MAX7219/7221 chips, but is included for API compatibility with SBK_BarDrive.

This value is computed as: maxRows(devIdx) × maxColumns() For MAX7219/7221, this is always 8 × 8 = 64 segments per device.

Returns: Total number of addressable LED segments (pixels) for this device.

◆ setBrightness()

void SBK_MAX72xxHard::setBrightness	(	uint8_t	devIdx,
		uint8_t	brightness )

Set display brightness for a specific device.

Parameters

devIdx	Target device index.
brightness	Value from 0 (min) to 15 (max).

◆ setCol()

void SBK_MAX72xxHard::setCol	(	uint8_t	devIdx,
		uint8_t	colIdx,
		uint8_t	value )

Set the entire col value for a specific device (buffer only).

Parameters

devIdx	Index of the target device.
colIdx	Column number (0 to 7).
value	8-bit value for the row.

◆ setLed()

void SBK_MAX72xxHard::setLed	(	uint8_t	devIdx,
		uint8_t	rowIdx,
		uint8_t	colIdx,
		bool	state )

Set the state of a specific LED in the device’s internal matrix buffer.

Parameters

devIdx	Index of the target device (0-based in daisy chain).
rowIdx	Logical rowIdx index (0 to maxRows(_devIdx) - 1) — vertical position (anode).
colIdx	Logical column index (0 to maxColumns() - 1) — horizontal position (cathode).
state	true = LED ON, false = LED OFF.

Note

The coordinate system follows a standard [row, col] layout. For MAX72xx drivers:

row corresponds to SEGx (segment outputs, V+ source = anode)
col corresponds to DIGx (digit selectors, GND sink = cathode)

This function updates the internal buffer; call show() to apply changes to hardware.

◆ setScanLimit()

void SBK_MAX72xxHard::setScanLimit	(	uint8_t	devIdx,
		uint8_t	limit )

Set the scan limit (number of active digits) for a specific device.

Parameters

devIdx	Target device index.
limit	Value from 0 to 7.

◆ setShutdown()

void SBK_MAX72xxHard::setShutdown	(	uint8_t	devIdx,
		bool	status )

Enable or disable shutdown mode on a specific device.

Parameters

devIdx	Index of the target device.
status	false = shutdown, true = normal operation

◆ setSPIClock()

void SBK_MAX72xxHard::setSPIClock ( uint32_t frequency )

Set SPI clock speed (hardware SPI only).

Parameters

frequency Frequency in Hz (e.g., 1000000 for 1 MHz).

◆ show() [1/2]

void SBK_MAX72xxHard::show ( )

Push the internal display buffer to all connected devices.

This flushes all buffered LED states to the physical hardware for every device managed by this driver instance. Use this after making multiple setLed() calls to apply the changes to the display.

Typically used in split-device or multi-bar meter setups.

◆ show() [2/2]

void SBK_MAX72xxHard::show ( uint8_t devIdx )

Push the internal display buffer to a specific device.

Parameters

devIdx Index of the target device (0-based in the daisy chain).

Only the specified device's display will be updated. Useful for optimized partial updates when only one device has changed.

Note: The driver must track changes correctly for this to be meaningful.

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

C:/Users/sbara/OneDrive/Documents/GitHub/SBK_MAX72xx/src/SBK_MAX72xxHard.h
C:/Users/sbara/OneDrive/Documents/GitHub/SBK_MAX72xx/src/SBK_MAX72xxHard.cpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ SBK_MAX72xxHard()

Member Function Documentation

◆ clear()

◆ devsNum()

◆ end()

◆ getLed()

◆ maxColumns()

◆ maxRows()

◆ maxSegments()

◆ setBrightness()

◆ setCol()

◆ setLed()

◆ setScanLimit()

◆ setShutdown()

◆ setSPIClock()

◆ show() [1/2]

◆ show() [2/2]