Maxim Integrated / MAX7219

Library for the MAX7219 LED display driver

Dependents:   MAXREFDES99_demo MAXREFDES99_RTC_Display nucleo_spi_max7219_led8x8 max7219 ... more

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Max7219 Class Reference
Public Types | Public Member Functions

Max7219 Class Reference

Serially Interfaced, 8-Digit, LED Display Driver. More...

#include <max7219.h>

Public Types

enum  max7219_register_e
 

Digit and Control Registers.

More...
enum  max7219_intensity_e
 

Intensity values.

More...
enum  max7219_scan_limit_e
 

Scan limit for mutiplexing digits.

More...

Public Member Functions

 Max7219 (SPI *spi_bus, PinName cs)
 Constructor for Max7219 Class.
 Max7219 (PinName mosi, PinName miso, PinName sclk, PinName cs)
 Constructor for Max7219 Class.
 ~Max7219 ()
 Default destructor for Max7219 Class.
int32_t set_num_devices (uint8_t num_devices)
 Sets the number of MAX7219 devices being used.
void set_display_test (void)
 Tests all devices being used.
void clear_display_test (void)
 Stops test.
int32_t init_device (max7219_configuration_t config)
 Initializes specific device in display with given config data.
void init_display (max7219_configuration_t config)
 Initializes all devices with given config data.
int32_t enable_device (uint8_t device_number)
 Enables specific device in display.
void enable_display (void)
 Enables all device in display.
int32_t disable_device (uint8_t device_number)
 Disables specific device in display.
void disable_display (void)
 Disables all devices in display.
int32_t write_digit (uint8_t device_number, uint8_t digit, uint8_t data)
 Writes digit of given device with given data, user must enter correct data for decode_mode chosen.
int32_t clear_digit (uint8_t device_number, uint8_t digit)
 Clears digit of given device.
int32_t device_all_on (uint8_t device_number)
 Turns on all segments/digits of given device.
int32_t device_all_off (uint8_t device_number)
 Turns off all segments/digits of given device.
void display_all_on (void)
 Turns on all segments/digits of display.
void display_all_off (void)
 Turns off all segments/digits of display.

Detailed Description

Serially Interfaced, 8-Digit, LED Display Driver.

The MAX7219/MAX7221 are compact, serial input/output common-cathode display drivers that interface microprocessors (µPs) to 7-segment numeric LED displays of up to 8 digits, bar-graph displays, or 64 individual LEDs. Included on-chip are a BCD code-B decoder, multiplex scan circuitry, segment and digit drivers, and an 8x8 static RAM that stores each digit. Only one external resistor is required to set the segment current for all LEDs. The MAX7221 is compatible with SPI™, QSPI™, and MICROWIRE™, and has slew-rate-limited segment drivers to reduce EMI.

 #include "mbed.h"
 #include "max7219.h"

 Max7219 max7219(SPI0_MOSI, SPI0_MISO, SPI0_SCK, SPI0_SS);

 int main()
 {
     max7219_configuration_t cfg = {
         .device_number = 1,
         .decode_mode = 0,
         .intensity = Max7219::MAX7219_INTENSITY_8,
         .scan_limit = Max7219::MAX7219_SCAN_8
     };

     max7219.init_device(cfg);
     max7219.enable_device(1);
     max7219.set_display_test();
     wait(1);
     max7219.clear_display_test();

     while (1) {
         max7219.write_digit(1, Max7219::MAX7219_DIGIT_0, ...
     }
 }

Definition at line 102 of file max7219.h.

Member Enumeration Documentation

enum max7219_intensity_e

Intensity values.

Digital control of display brightness is provided by an internal pulse-width modulator, which is controlled by the lower nibble of the intensity register.

Definition at line 135 of file max7219.h.

enum max7219_register_e

Digit and Control Registers.

The 14 addressable digit and control registers.

Definition at line 110 of file max7219.h.

enum max7219_scan_limit_e

Scan limit for mutiplexing digits.

The scan-limit register sets how many digits are displayed, from 1 to 8. They are displayed in a multiplexed manner with a typical display scan rate of 800Hz with 8 digits displayed.

Definition at line 163 of file max7219.h.

Constructor & Destructor Documentation

Max7219 ( SPI *  spi_bus,
PinName  cs 
)

Constructor for Max7219 Class.

Allows user to pass pointer to existing SPI bus

On Entry:

Parameters:
[in]spi_bus- pointer to existing SPI object
[in]cs- pin to use for cs

On Exit:

Returns:
None

Definition at line 39 of file max7219.cpp.

Max7219 ( PinName  mosi,
PinName  miso,
PinName  sclk,
PinName  cs 
)

Constructor for Max7219 Class.

Allows user to specify SPI peripheral to use

On Entry:

Parameters:
[in]mosi- pin to use for mosi
[in]miso- pin to use for miso
[in]sclk- pin to use for sclk
[in]cs- pin to use for cs

On Exit:

Returns:
None

Definition at line 49 of file max7219.cpp.

~Max7219 (  )

Default destructor for Max7219 Class.

Destroys SPI object if owner

On Entry:

On Exit:

Returns:
None

Definition at line 61 of file max7219.cpp.

Member Function Documentation

int32_t clear_digit ( uint8_t  device_number,
uint8_t  digit 
)

Clears digit of given device.

On Entry:

Parameters:
[in]device_number- device to write too
[in]digit- digit to clear

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0
Returns -3 if digit > 8
Returns -4 if digit < 1

Definition at line 400 of file max7219.cpp.

void clear_display_test ( void   )

Stops test.

Clear bit0 of DISPLAY_TEST regiser in all devices

On Entry:

On Exit:

Returns:
None

Definition at line 103 of file max7219.cpp.

int32_t device_all_off ( uint8_t  device_number )

Turns off all segments/digits of given device.

On Entry:

Parameters:
[in]device_number- device to write too

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0

Definition at line 482 of file max7219.cpp.

int32_t device_all_on ( uint8_t  device_number )

Turns on all segments/digits of given device.

On Entry:

Parameters:
[in]device_number- device to write too

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0

Definition at line 450 of file max7219.cpp.

int32_t disable_device ( uint8_t  device_number )

Disables specific device in display.

On Entry:

Parameters:
[in]device_number- device to disable

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0

Definition at line 294 of file max7219.cpp.

void disable_display ( void   )

Disables all devices in display.

On Entry:

On Exit:

Returns:
None

Definition at line 334 of file max7219.cpp.

void display_all_off ( void   )

Turns off all segments/digits of display.

On Entry:

On Exit:

Returns:
None

Definition at line 528 of file max7219.cpp.

void display_all_on ( void   )

Turns on all segments/digits of display.

On Entry:

On Exit:

Returns:
None

Definition at line 513 of file max7219.cpp.

int32_t enable_device ( uint8_t  device_number )

Enables specific device in display.

On Entry:

Parameters:
[in]device_number- device to enable

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0

Definition at line 239 of file max7219.cpp.

void enable_display ( void   )

Enables all device in display.

On Entry:

On Exit:

Returns:
None

Definition at line 279 of file max7219.cpp.

int32_t init_device ( max7219_configuration_t  config )

Initializes specific device in display with given config data.

On Entry:

Parameters:
[in]config- Structure containing configuration data of device

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0

Definition at line 118 of file max7219.cpp.

void init_display ( max7219_configuration_t  config )

Initializes all devices with given config data.

All devices are configured with given data

On Entry:

Parameters:
[in]config- Structure containing configuration data On Exit:
Returns:
None

Definition at line 199 of file max7219.cpp.

void set_display_test ( void   )

Tests all devices being used.

Sets bit0 of DISPLAY_TEST regiser in all devices

On Entry:

On Exit:

Returns:
None

Definition at line 88 of file max7219.cpp.

int32_t set_num_devices ( uint8_t  num_devices )

Sets the number of MAX7219 devices being used.

Defaults to one

On Entry:

Parameters:
[in]num_devices- number of MAX7219 devices being used, max of 255

On Exit:

Returns:
Returns number of devices

Definition at line 73 of file max7219.cpp.

int32_t write_digit ( uint8_t  device_number,
uint8_t  digit,
uint8_t  data 
)

Writes digit of given device with given data, user must enter correct data for decode_mode chosen.

On Entry:

Parameters:
[in]device_number- device to write too
[in]digit- digit to write
[in]data- data to write

On Exit:

Returns:
Returns 0 on success
Returns -1 if device number is > _num_devices
Returns -2 if device number is 0
Returns -3 if digit > 8
Returns -4 if digit < 1

Definition at line 350 of file max7219.cpp.

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