MAX7219 Class Reference

MAX7219 and MAX7221 controller. More...

#include <MAX7219.h>

Public Member Functions
	MAX7219 (SPI *spi, int numDevices=1)
	Create a new MAX7219 controller. More...
void	clearDisplay (int addr)
	Switch all Leds on the display off. More...
int	getDeviceCount ()
	Gets the number of devices attached to this MAX7219. More...
void	setChar (int digit, char value, bool dp=false, int addr=0)
	Display a character on a 7-Segment display. More...
void	setColumn (int col, uint8_t value, int addr=0)
	Set all 8 Led's in a column to a new state. More...
void	setDigit (int digit, uint8_t value, bool dp=false, int addr=0)
	Display a hexadecimal digit on a 7-Segment Display. More...
void	setIntensity (int intensity, int addr=0)
	Set the brightness of the display. More...
void	setLed (int row, int col, bool state, int addr=0)
	Set the status of a single Led. More...
void	setNumber (uint32_t number, int addr=0)
	Display a number on the 7-Segment display. More...
void	setRow (int row, uint8_t value, int addr=0)
	Set all 8 Led's in a row to a new state. More...
void	setScanLimit (int limit, int addr=0)
	Set the number of digits (or rows) to be displayed. See datasheet for side effects of the scanlimit on the brightness of the display. More...
void	shutdown (bool status, int addr=0)
	Set the shutdown (power saving) mode for the device. More...

Detailed Description

MAX7219 and MAX7221 controller.

This is a port of the Arduino MAX7219 class to the ESP32. We can attach multiple IC instances daisy chained together. Each device has its own address with the first device being 0 (the default).

All the devices are in shutdown mode by default when we start. Any devices that are to be used must be taken out of shutdown mode with a call to:

shutdown(false);

For a given configuration, we are likely going to work with the MAX7219 as either an 8 digit 7 segment LED driver or an 8x8 led matrix. Working with the two styles have similarities and distinctions. For the 7 segment LED, we will typically use setDigit(), setChar() and setNumber() to set digits while in the 8x8 led matrix, we will use setLed(), setRow() and setColumn().

Constructor & Destructor Documentation

MAX7219::MAX7219	(	SPI *	spi,
		int	numDevices = 1
	)

Create a new MAX7219 controller.

Parameters

[in]	spi	SPI controller.
[in]	numDevices	maximum number of devices that can be controlled that are daisy chained together.

Member Function Documentation

void MAX7219::clearDisplay

(

int

addr

)

Switch all Leds on the display off.

Parameters

[in]

addr

Address of the display to control.

int MAX7219::getDeviceCount

(

)

Gets the number of devices attached to this MAX7219.

Returns

The number of devices on this MAX7219.

void MAX7219::setChar	(	int	digit,
		char	value,
		bool	dp = false,
		int	addr = 0
	)

Display a character on a 7-Segment display.

There are only a few characters that make sense here : '0','1','2','3','4','5','6','7','8','9','0', 'A','b','c','d','E','F','H','L','P', '.','-','_',' '

Parameters

[in]	digit	The position of the character on the display (0..7).
[in]	value	The character to be displayed.
[in]	dp	Sets the decimal point.
[in]	addr	Address of the display.

void MAX7219::setColumn	(	int	col,
		uint8_t	value,
		int	addr = 0
	)

Set all 8 Led's in a column to a new state.

Parameters

[in]	col	column which is to be set (0..7).
[in]	value	each bit set to 1 will light up the corresponding Led.
[in]	addr	address of the display.

void MAX7219::setDigit	(	int	digit,
		uint8_t	value,
		bool	dp = false,
		int	addr = 0
	)

Display a hexadecimal digit on a 7-Segment Display.

Parameters

[in]	digit	The position of the digit on the display (0..7).
[in]	value	The value to be displayed. (0x00..0x0F).
[in]	dp	Sets the decimal point.
[in]	addr	Address of the display.

void MAX7219::setIntensity	(	int	intensity,
		int	addr = 0
	)

Set the brightness of the display.

Parameters

[in]	intensity	the brightness of the display. (0..15).
[in]	addr	The address of the display to control.

void MAX7219::setLed	(	int	row,
		int	col,
		bool	state,
		int	addr = 0
	)

Set the status of a single Led.

Parameters

[in]	row	The row of the Led (0..7).
[in]	col	The column of the Led (0..7).
[in]	state	If true the led is switched on, if false it is switched off.
[in]	addr	Address of the display.

void MAX7219::setNumber	(	uint32_t	number,
		int	addr = 0
	)

Display a number on the 7-Segment display.

A non negative whole number that is 8 digits or less is displayed.

Parameters

[in]	number	The number to display.
[in]	addr	Address of the display.

void MAX7219::setRow	(	int	row,
		uint8_t	value,
		int	addr = 0
	)

Set all 8 Led's in a row to a new state.

Parameters

[in]	row	Row which is to be set (0..7).
[in]	value	Each bit set to 1 will light up the corresponding Led.
[in]	addr	Address of the display.

void MAX7219::setScanLimit	(	int	limit,
		int	addr = 0
	)

Set the number of digits (or rows) to be displayed. See datasheet for side effects of the scanlimit on the brightness of the display.

Parameters

[in]	limit	Number of digits to be displayed (1..8).
[in]	addr	Address of the display to control.

void MAX7219::shutdown	(	bool	status,
		int	addr = 0
	)

Set the shutdown (power saving) mode for the device.

Parameters

[in]	status	If true the device goes into power-down mode. Set to false for normal operation.
[in]	addr	The address of the display to control.

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

• MAX7219.h
• MAX7219.cpp