MAX7219_SS_RPI Class Reference

Drive MAX7219 seven segment displays. More...

#include <MAX7219_7SEG_RDL.hpp>

Public Types
enum	DecodeMode_e : uint8_t { DecodeModeNone = 0x00 , DecodeModeBCDOne = 0x01 , DecodeModeBCDTwo = 0x0F , DecodeModeBCDThree = 0xFF }
enum	CodeBFont_e : uint8_t {   CodeBFontZero = 0x00 , CodeBFontOne = 0x01 , CodeBFontTwo = 0x02 , CodeBFontThree = 0x03 ,   CodeBFontFour = 0x04 , CodeBFontFive = 0x05 , CodeBFontSix = 0x06 , CodeBFontSeven = 0x07 ,   CodeBFontEight = 0x08 , CodeBFontNine = 0x09 , CodeBFontDash = 0x0A , CodeBFontE = 0x0B ,   CodeBFontH = 0x0C , CodeBFontL = 0x0D , CodeBFontP = 0x0E , CodeBFontSpace = 0x0F }
enum	TextAlignment_e : uint8_t { AlignLeft = 0 , AlignRight = 1 , AlignRightZeros = 2 }
enum	DecimalPoint_e : uint8_t { DecPointOff = 0 , DecPointOn = 1 }
enum	Intensity_e : uint8_t { IntensityMin = 0x00 , IntensityDefault = 0x08 , IntensityMax = 0x0F }
enum	ScanLimit_e : uint8_t {   ScanOneDigit = 0x00 , ScanTwoDigit = 0x01 , ScanThreeDigit = 0x02 , ScanFourDigit = 0x03 ,   ScanFiveDigit = 0x04 , ScanSixDigit = 0x05 , ScanSevenDigit = 0x06 , ScanEightDigit = 0x07 }
enum	RegisterModes_e : uint8_t {   MAX7219_REG_NOP = 0x00 , MAX7219_REG_DecodeMode = 0x09 , MAX7219_REG_Intensity = 0x0A , MAX7219_REG_ScanLimit = 0x0B ,   MAX7219_REG_ShutDown = 0x0C , MAX7219_REG_DisplayTest = 0x0F }

Public Member Functions
	MAX7219_SS_RPI (uint8_t clock, uint8_t chipSelect, uint8_t data, int gpioDev)
	Constructor for class MAX7219_SS_RPI software SPI.
	MAX7219_SS_RPI (int device, int channel, int speed, int flags)
	Constructor for class MAX7219_SS_RPI hardware SPI.
rdlib::Return_Codes_e	InitDisplay (ScanLimit_e numDigits, DecodeMode_e decodeMode)
	Init the display.
void	ClearDisplay (void)
	Clear the display.
rdlib::Return_Codes_e	DisplayEndOperations (void)
	End display operations, called at end of program.
void	SetBrightness (uint8_t brightness)
	sets the brighttness of display
void	DisplayTestMode (bool OnOff)
	Turn on and off the Display Test Mode.
void	ShutdownMode (bool OnOff)
	Turn on and off the Shutdown Mode.
uint16_t	GetCommDelay (void)
	Get the communication delay value.
void	SetCommDelay (uint16_t commDelay)
	Set the communication delay value.
bool	GetHardwareSPI (void)
	get value of _HardwareSPI , true hardware SPI on , false off.
uint8_t	GetCurrentDisplayNumber (void)
	Get the Current Display Number.
void	SetCurrentDisplayNumber (uint8_t)
	Set the Current Display Number.
void	DisplayChar (uint8_t digit, uint8_t value, DecimalPoint_e decimalPoint)
	Displays a character on display.
void	DisplayText (char *text, TextAlignment_e TextAlignment)
	Displays a text string on display.
void	DisplayText (char *text)
	Displays a text string on display.
void	DisplayIntNum (unsigned long number, TextAlignment_e TextAlignment)
	Display an integer and leading zeros optional.
void	DisplayDecNumNibble (uint16_t numberUpper, uint16_t numberLower, TextAlignment_e TextAlignment)
	Display an integer in a nibble (4 digits on display)
void	DisplayBCDChar (uint8_t digit, CodeBFont_e value)
	Displays a character on display using MAX7219 Built in BCD code B font.
void	DisplayBCDText (char *text)
	Displays a BCD text string on display using MAX7219 Built in BCD code B font.
void	SetSegment (uint8_t digit, uint8_t segment)
	Set a seven segment LED ON.

Private Member Functions
void	HighFreqshiftOut (uint8_t value)
	Shifts out a uint8_t of data on to the MAX7219 SPI-like bus.
void	WriteDisplay (uint8_t RegisterCode, uint8_t data)
	Write to the MAX7219 display register.
uint8_t	ASCIIFetch (uint8_t character, DecimalPoint_e decimalPoint)
	Fetch's the seven segment code for a given ASCII code from the font.
void	SetDecodeMode (DecodeMode_e mode)
	Set the decode mode of the MAX7219 decode mode register.
void	SetScanLimit (ScanLimit_e numDigits)
	Set the decode mode of the MAX7219 decode mode register.
uint8_t	flipBitsPreserveMSB (uint8_t byte)
	Flips the positions of bits in a byte while preserving the MSB bit.

Private Attributes
uint8_t	_Display_CS
uint8_t	_Display_SDATA
uint8_t	_Display_SCLK
uint16_t	_CommDelay = 0
uint8_t	_NoDigits = 8
int	_DeviceNumGpioChip = 0
int	_GpioHandle = 0
int	_spiHandle = 0
int	_spiDev = 0
int	_spiChan = 0
int	_spiBaud = 50000
int	_spiFlags = 0
bool	_HardwareSPI = false
DecodeMode_e	CurrentDecodeMode
uint8_t	_CurrentDisplayNumber = 1

Detailed Description

Drive MAX7219 seven segment displays.

Member Enumeration Documentation

CodeBFont_e

enum MAX7219_SS_RPI::CodeBFont_e : uint8_t

sets BCD code B font (0-9, E, H, L,P, and -) Built-in font

Enumerator
CodeBFontZero	Code B decode for Zero
CodeBFontOne	Code B decode for One
CodeBFontTwo	Code B decode for Two
CodeBFontThree	Code B decode for Three
CodeBFontFour	Code B decode for Four
CodeBFontFive	Code B decode for Five
CodeBFontSix	Code B decode for Six
CodeBFontSeven	Code B decode for Seven
CodeBFontEight	Code B decode for Eight
CodeBFontNine	Code B decode for Nine
CodeBFontDash	Code B decode for Dash
CodeBFontE	Code B decode for letter E
CodeBFontH	Code B decode for letter H
CodeBFontL	Code B decode for letter L
CodeBFontP	Code B decode for letter P
CodeBFontSpace	Code B decode for Space

DecimalPoint_e

enum MAX7219_SS_RPI::DecimalPoint_e : uint8_t

Activate Decimal point segment

Enumerator
DecPointOff	Decimal point segment off
DecPointOn	Decimal point segment on

DecodeMode_e

enum MAX7219_SS_RPI::DecodeMode_e : uint8_t

The decode-mode register sets BCD code B or no-decode operation for each digit

Enumerator
DecodeModeNone	No decode for digits 7–0
DecodeModeBCDOne	Code B decode for digit 0, No decode for digits 7–1
DecodeModeBCDTwo	Code B decode for digits 3–0, No decode for digits 7–4
DecodeModeBCDThree	Code B decode for digits 7–0

Intensity_e

enum MAX7219_SS_RPI::Intensity_e : uint8_t

Set intensity/brightness of Display

Enumerator
IntensityMin	Minimum Intensity
IntensityDefault	Default Intensity
IntensityMax	Maximum Intensity

RegisterModes_e

enum MAX7219_SS_RPI::RegisterModes_e : uint8_t

Register opcodes of the MAZ7219 chip, Register Address Map

Enumerator
MAX7219_REG_NOP	No operation
MAX7219_REG_DecodeMode	Decode-Mode Register
MAX7219_REG_Intensity	Intensity Register, brightness of display
MAX7219_REG_ScanLimit	Scan Limit, The scan-limit register sets how many digits are displayed
MAX7219_REG_ShutDown	When the MAX7219 is in shutdown mode, the scan oscillator is halted, all segment current sources are pulled to ground, and all digit drivers are pulled to V+, thereby blanking the display.
MAX7219_REG_DisplayTest	Display-test mode turns all LEDs on by overriding, but not altering, all controls and digit registers

ScanLimit_e

enum MAX7219_SS_RPI::ScanLimit_e : uint8_t

The scan-limit register sets how many digits are displayed

Enumerator
ScanOneDigit	Scan One digit
ScanTwoDigit	Scan Two digit
ScanThreeDigit	Scan Three digit
ScanFourDigit	Scan Four digit
ScanFiveDigit	Scan Five digit
ScanSixDigit	Scan Six digit
ScanSevenDigit	Scan Seven digit
ScanEightDigit	Scan Eight digit

TextAlignment_e

enum MAX7219_SS_RPI::TextAlignment_e : uint8_t

Alignment of text on display

Enumerator
AlignLeft	Align text to the left on display
AlignRight	Align text to the right on display
AlignRightZeros	Add leading zeros to the text

Constructor & Destructor Documentation

MAX7219_SS_RPI() [1/2]

MAX7219_SS_RPI::MAX7219_SS_RPI	(	uint8_t	clock,
		uint8_t	chipSelect,
		uint8_t	data,
		int	gpioDev
	)

Constructor for class MAX7219_SS_RPI software SPI.

Parameters

clock	CLk pin
chipSelect	CS pin
data	DIO pin
gpioDev	The device number of a gpiochip. @

Note

overloaded this one is for Software SPI

MAX7219_SS_RPI() [2/2]

MAX7219_SS_RPI::MAX7219_SS_RPI	(	int	device,
		int	channel,
		int	speed,
		int	flags
	)

Constructor for class MAX7219_SS_RPI hardware SPI.

Parameters

device	A SPI device, >= 0.
channel	A SPI channel, >= 0.
speed	The speed of serial communication in bits per second.
flags	The flags may be used to modify the default behaviour. Set to 0(mode 0) for this device.

Note

overloaded this one is for Hardware SPI

Member Function Documentation

ASCIIFetch()

uint8_t MAX7219_SS_RPI::ASCIIFetch ( uint8_t  character, DecimalPoint_e  decimalPoint  )

private

Fetch's the seven segment code for a given ASCII code from the font.

Parameters

character	The ASCII character to lookup
decimalPoint	Is the decimal point(dp) to be set or not.

Returns

The seven segment representation of the ASCII character in a byte dpabcdefg

DisplayBCDChar()

void MAX7219_SS_RPI::DisplayBCDChar	(	uint8_t	digit,
		CodeBFont_e	value
	)

Displays a character on display using MAX7219 Built in BCD code B font.

Parameters

digit	The digit to display character in, 7-0 ,7 = LHS 0 =RHS
value	The BCD character to display

Note

sets BCD code B font (0-9, E, H, L,P, and -) Built-in font

DisplayBCDText()

void MAX7219_SS_RPI::DisplayBCDText

(

char *

text

)

Displays a BCD text string on display using MAX7219 Built in BCD code B font.

Parameters

text	pointer to character array containg text string

Note

sets BCD code B font (0-9, E, H, L,P, and -) Built-in font

DisplayChar()

void MAX7219_SS_RPI::DisplayChar	(	uint8_t	digit,
		uint8_t	character,
		DecimalPoint_e	decimalPoint
	)

Displays a character on display.

Parameters

digit	The digit to display character in, 7-0 ,7 = LHS 0 =RHS
character	The ASCII character to display
decimalPoint	Is the decimal point(dp) to be set or not.

DisplayDecNumNibble()

void MAX7219_SS_RPI::DisplayDecNumNibble	(	uint16_t	numberUpper,
		uint16_t	numberLower,
		TextAlignment_e	TextAlignment
	)

Display an integer in a nibble (4 digits on display)

Parameters

numberUpper	upper nibble integer 2^16
numberLower	lower nibble integer 2^16
TextAlignment	left or right alignment or leading zeros

Note

Divides the display into two nibbles and displays a Decimal number in each. takes in two numbers 0-9999 for each nibble.

DisplayEndOperations()

rdlib::Return_Codes_e MAX7219_SS_RPI::DisplayEndOperations

(

void

)

End display operations, called at end of program.

Returns

a rdlib::Return_Codes_e code

1. rdlib::Success
2. rdlib::GpioPinFree
3. rdlib::SPICloseFailure
4. rdlib::GpioChipDevice

DisplayIntNum()

void MAX7219_SS_RPI::DisplayIntNum	(	unsigned long	number,
		TextAlignment_e	TextAlignment
	)

Display an integer and leading zeros optional.

Parameters

number	integer to display 2^32
TextAlignment	enum text alignment, left or right alignment or leading zeros

DisplayTestMode()

void MAX7219_SS_RPI::DisplayTestMode

(

bool

OnOff

)

Turn on and off the Display Test Mode.

Parameters

OnOff

true = display test mode on , false display Test Mode off

Note

Display-test mode turns all LEDs on

DisplayText() [1/2]

void MAX7219_SS_RPI::DisplayText

(

char *

text

)

Displays a text string on display.

Parameters

text	pointer to character array containg text string

Note

This method is overloaded, see also DisplayText(char *, TextAlignment_e )

DisplayText() [2/2]

void MAX7219_SS_RPI::DisplayText	(	char *	text,
		TextAlignment_e	TextAlignment
	)

Displays a text string on display.

Parameters

text	pointer to character array containg text string
TextAlignment	left or right alignment or leading zeros

Note

This method is overloaded, see also DisplayText(char *)

flipBitsPreserveMSB()

uint8_t MAX7219_SS_RPI::flipBitsPreserveMSB ( uint8_t  byte )

private

Flips the positions of bits in a byte while preserving the MSB bit.

Parameters

byte	A byte of data, ASCII character

Returns

A byte from font representing LED segment data with bits positions flipped and MSB bit value preserved

The reason for this function is that the MAX7219 requires ASCII segment data in following order : dp-abcdefg but the font we use is dp-gfedcba where letters represent seven segment LEDS, and dp represents decimal point.. We flip the bits in the code rather than change the font data in font file because the font data is used by other modules(TM1638 + TM1637) and they use dp-gfedcba order. Thus we can share same font file between all seven segment modules.

GetCommDelay()

uint16_t MAX7219_SS_RPI::GetCommDelay

(

void

)

Get the communication delay value.

Returns

Get the communication delay value uS Software SPi

GetCurrentDisplayNumber()

uint8_t MAX7219_SS_RPI::GetCurrentDisplayNumber

(

void

)

Get the Current Display Number.

Returns

Get the Current Display Number

GetHardwareSPI()

bool MAX7219_SS_RPI::GetHardwareSPI

(

void

)

get value of _HardwareSPI , true hardware SPI on , false off.

Returns

_HardwareSPI , true hardware SPI on , false off.

HighFreqshiftOut()

void MAX7219_SS_RPI::HighFreqshiftOut ( uint8_t  value )

private

Shifts out a uint8_t of data on to the MAX7219 SPI-like bus.

Parameters

value

The uint8_t of data to shift out

Note

_CommDelay microsecond delay may have to be adjusted depending on processor

InitDisplay()

rdlib::Return_Codes_e MAX7219_SS_RPI::InitDisplay	(	ScanLimit_e	numDigits,
		DecodeMode_e	decodeMode
	)

Init the display.

Parameters

numDigits	scan limit set to 8 normally , advanced use only
decodeMode	Must users will use 0x00 here

Returns

a rdlib::Return_Codes_e code

1. rdlib::Success
2. rdlib::GpioPinCliam
3. rdlib::SPIOpenFailure
4. rdlib::GpioChipDevice

Note

when cascading supplies init display one first always!

SetBrightness()

void MAX7219_SS_RPI::SetBrightness

(

uint8_t

brightness

)

sets the brighttness of display

Parameters

brightness

rang 0x00 to 0x0F , 0x00 being least bright.

SetCommDelay()

void MAX7219_SS_RPI::SetCommDelay

(

uint16_t

commDelay

)

Set the communication delay value.

Parameters

commDelay

Set the communication delay value uS software SPI

SetCurrentDisplayNumber()

void MAX7219_SS_RPI::SetCurrentDisplayNumber

(

uint8_t

DisplayNum

)

Set the Current Display Number.

Parameters

DisplayNum

Set the Current Display Number

SetDecodeMode()

void MAX7219_SS_RPI::SetDecodeMode ( DecodeMode_e  mode )

private

Set the decode mode of the MAX7219 decode mode register.

Parameters

mode	Set to 0x00 for most users

SetScanLimit()

void MAX7219_SS_RPI::SetScanLimit ( ScanLimit_e  numDigits )

private

Set the decode mode of the MAX7219 decode mode register.

Parameters

numDigits

Usually set to 7(digit 8) The scan-limit register sets how many digits are displayed, from 1 to 8.

Note

Advanced users only , read datasheet

SetSegment()

void MAX7219_SS_RPI::SetSegment	(	uint8_t	digit,
		uint8_t	segment
	)

Set a seven segment LED ON.

Parameters

digit	The digit to set segment in, 7-0 ,7 = LHS 0 =RHS
segment	The segment of seven segment to set dpabcdefg

ShutdownMode()

void MAX7219_SS_RPI::ShutdownMode

(

bool

OnOff

)

Turn on and off the Shutdown Mode.

Parameters

OnOff

true = Shutdown mode on , false shutdown mode off

Note

power saving mode

WriteDisplay()

void MAX7219_SS_RPI::WriteDisplay ( uint8_t  RegisterCode, uint8_t  data  )

private

Write to the MAX7219 display register.

Parameters

RegisterCode	the register to write to
data	The data byte to send to register

Member Data Documentation

_CommDelay

uint16_t MAX7219_SS_RPI::_CommDelay = 0

private

uS delay used in communications SW SPI, User adjust

_CurrentDisplayNumber

uint8_t MAX7219_SS_RPI::_CurrentDisplayNumber = 1

private

Which display the user wishes to write to in a cascade of connected displays

_DeviceNumGpioChip

int MAX7219_SS_RPI::_DeviceNumGpioChip = 0

private

SWSPI The device number of a gpiochip ls /dev/gpio

_Display_CS

uint8_t MAX7219_SS_RPI::_Display_CS

private

GPIO connected to CS on MAX7219, SW SPI only

_Display_SCLK

uint8_t MAX7219_SS_RPI::_Display_SCLK

private

GPIO connected to CLK on MAX7219, SW SPI only

_Display_SDATA

uint8_t MAX7219_SS_RPI::_Display_SDATA

private

GPIO connected to DIO on MAX7219, SW SPI only

_GpioHandle

int MAX7219_SS_RPI::_GpioHandle = 0

private

This holds a handle to a device opened by lgGpiochipOpen

_HardwareSPI

bool MAX7219_SS_RPI::_HardwareSPI = false

private

Is the Hardware SPI on , true yes , false SW SPI

_NoDigits

uint8_t MAX7219_SS_RPI::_NoDigits = 8

private

Number of digits in display

_spiBaud

int MAX7219_SS_RPI::_spiBaud = 50000

private

The speed of serial communication in bits per second.

_spiChan

int MAX7219_SS_RPI::_spiChan = 0

private

A SPI channel, >= 0.

_spiDev

int MAX7219_SS_RPI::_spiDev = 0

private

A SPI device, >= 0.

_spiFlags

int MAX7219_SS_RPI::_spiFlags = 0

private

The flags 2 LSB defines SPI mode See MAX7219_SS_RPI constructor notes

_spiHandle

int MAX7219_SS_RPI::_spiHandle = 0

private

Hold a handle for the SPI device on the channel lgSpiOpen(

CurrentDecodeMode

DecodeMode_e MAX7219_SS_RPI::CurrentDecodeMode

private

Enum to store current decode mode

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

• MAX7219_7SEG_RDL.hpp
• MAX7219_7SEG_RDL.cpp