https://miguelpynto.github.io/ShiftDisplay/

ShiftDisplay

by MiguelPynto

Arduino library for driving 7-segment displays using shift registers

• Show numbers, text, and custom characters
• Use the whole display as one, or separate by individual sections
• Compatible with multiplexed drive and constant drive
• Compatible with common cathode and common anode
• Compatible with custom made and commercial display modules
• Maximum of 8 digits (for now)
• Concatenate multiple displays as one
• Only 3 pins used on Arduino

Hardware

• 1x (or more) 7-segment LED display
• 2x shift register (eg: 74HC595, TPIC6B595)
• 2x 0.1uF ceramic capacitor
• 8x (per display) 220 Ohm resistor

Wiring

1. Connect Arduino board to shift registers:

2. Connect shift registers to display(s):

Install

1. Launch the Arduino IDE
2. Open the Library Manager by going to menu: Sketch > Include Library > Manage Libraries
3. Search for ShiftDisplay library by typing shiftdisplay in Filter your search
4. Select ShiftDisplay by MiguelPynto and click install

Example

#include <ShiftDisplay.h>

ShiftDisplay display(COMMON_CATHODE, 3);

void setup() {
    for (int i = 3; i > 0; i--) {
        // store number and show it for 400ms
        display.set(i, ALIGN_CENTER);
        display.show(400);
        // add dot to stored number and show it for 400ms
        display.changeDot(1);
        display.show(400);
    }
    display.set("GO"); // store "GO"
}

void loop() {
    display.update(); // show stored "GO" while in loop
}

Reference

Constructors

• ShiftDisplay()

  • ShiftDisplay display([latchPin, clockPin, dataPin, ]displayType, displaySize[, displayDrive])
  • ShiftDisplay display([latchPin, clockPin, dataPin, ]displayType, sectionSizes[, displayDrive])
  • ShiftDisplay display([latchPin, clockPin, dataPin, ]displayType, displaySize, swappedShiftRegisters[, indexes])
  • ShiftDisplay display([latchPin, clockPin, dataPin, ]displayType, sectionSizes, swappedShiftRegisters[, indexes])

  Create a ShiftDisplay object, initialize the library using the interface pins, display properties and configurations. A display can be set as a whole, or divided by sections. Sections can be a logical separation (for example hours and minutes on a 4 digit clock display), or a physical separation (for example timer and score on a scoreboard with multiple displays).

  latchPin, clockPin, dataPin (int): number of the Arduino digital pins connected to the latch, clock and data pins of the shift registers; if is not specified, the default pins are 6 for latch, 7 for clock, and 5 for data.

  displayType (DisplayType): type of the display, can be common anode or common cathode.

  displaySize (int): quantity of digits on the display.

  sectionSizes (int[]): quantity of digits for each section, defined by each value in array; end array with a 0 or lower value.

  displayDrive (DisplayDrive): drive algorithm of the display, can be multiplexed drive or static drive; if is not specified, the default is MULTIPLEXED_DRIVE.

  swappedShiftRegisters (bool): when set to true, changes shift registers order to first being digit index controller, and second being segment controller; if is specified, displayDrive is forced to MULTIPLEXED_DRIVE.

  indexes (int[]): custom digit index order, each array position contains the index of where the digit is output from the shift register; if is not specified, the default is { 0, 1, 2, 3, 4, 5, 6, 7 }.

Functions

• set()

  • display.set(number[, decimalPlaces][, leadingZeros][, alignment])
  • display.set(text[, alignment])
  • display.set(customs)
  • display.set(characters, dots)

  Encode and store a value for showing next on the display. The entire previous value is cleared.

  display (ShiftDisplay): object where function is called.

  number (int | long | float | double): numeric value to set; if is too big to fit in the display, it is trimmed according to alignment.

  text (char | char[] | String): textual value to set; valid characters are 0-9 a-z A-Z -, other characters are converted to space; char array must be null-terminated; if is too big to fit in the display, it is trimmed according to alignment.

  customs (byte[]): custom characters to set, encoded in abcdefgp format, each byte is a character on the display, from left to right; array length must match display size.

  characters (char[]): characters to set, each char is a character on the display, from left to right; valid characters are 0-9 a-z A-Z -, other characters are converted to a space; array length must match display size.

  dots (bool[]): dot values to set, each bool is a dot on the display, from left to right; true to show the dot, false to hide the dot; array length must match display size.

  decimalPlaces (int): quantity of digits following the decimal point; the value is rounded according to this; if is set to 0, the decimal point will be removed; if is not specified, the default is 1 for real numbers and 0 for integer numbers.

  leadingZeros (bool): show or hide zeros on the left of value; if is not specified, the default is false.

  alignment (Alignment): alignment of the value on the display; if is not specified, the default is ALIGN_RIGHT for numbers and ALIGN_LEFT for text.

• changeDot()

  • display.changeDot(index[, dot])

  Modify the stored value by adding or hiding a dot.

  display (ShiftDisplay): object where function is called.

  index (int): position on the display to change the dot, starting at 0 for the leftmost; if is out of bounds, function does not have any effect.

  dot (bool): true to show the dot, false to hide the dot; if is not specified, the default is true.

• changeCharacter()

  • display.changeCharacter(index, custom)

  Modify the stored value by replacing the character (and dot) with a custom character.

  display (ShiftDisplay): object where function is called.

  index (int): position on the display to change the character, starting at 0 for the leftmost; if is out of bounds, function does not have any effect.

  custom (byte): custom character to set, encoded in abcdefgp format.

• setAt()

  • display.setAt(section, number[, decimalPlaces][, leadingZeros][, alignment])
  • display.setAt(section, text[, alignment])
  • display.setAt(section, customs)
  • display.setAt(section, characters, dots)

  Encode and store a value for showing next on the specified section. The section previous value is cleared.

  display (ShiftDisplay): object where function is called.

  section (int): position of the section on the display to set the value, starting at 0 for the first; if is out of bounds, function does not have any effect.

  number (int | long | float | double): numeric value to set; if is too big to fit in the section, it is trimmed according to alignment.

  text (char | char[] | String): textual value to set; valid characters are 0-9 a-z A-Z -, other characters are converted to space; char array must be null-terminated; if is too big to fit in the section, it is trimmed according to alignment.

  customs (byte[]): custom characters to set, encoded in abcdefgp format, each byte is a character on the section, from left to right; array length must match section size.

  characters (char[]): characters to set, each char is a character on the section, from left to right; valid characters are 0-9 a-z A-Z -, other characters are converted to a space; array length must match section size.

  dots (bool[]): dot values to set, each bool is a dot on the section, from left to right; true to show the dot, false to hide the dot; array length must match section size.

  decimalPlaces (int): quantity of digits following the decimal point; the value is rounded according to this; if is set to 0, the decimal point will be removed; if is not specified, the default is 1 for real numbers and 0 for integer numbers.

  leadingZeros (bool): show or hide zeros on the left of value; if is not specified, the default is false.

  alignment (Alignment): alignment of the value on the section; if is not specified, the default is ALIGN_RIGHT for numbers and ALIGN_LEFT for text.

• changeDotAt()

  • display.changeDotAt(section, index[, dot])

  Modify the stored value by adding or hiding a dot in a section.

  display (ShiftDisplay): object where function is called.

  section (int): position of the section on the display to change the dot, starting at 0 for the first; if is out of bounds, function does not have any effect.

  index (int): position on the section to change the dot, starting at 0 for the leftmost; if is out of bounds, function does not have any effect.

  dot (bool): true to show the dot, false to hide the dot; if is not specified, the default is true.

• changeCharacterAt()

  • display.changeCharacterAt(section, index, custom)

  Modify the stored value by replacing the character (and dot) with a custom character in a section.

  display (ShiftDisplay): object where function is called.

  section (int): position of the section on the display to change the character, starting at 0 for the first; if is out of bounds, function does not have any effect.

  index (int): position on the section to change the character, starting at 0 for the leftmost; if is out of bounds, function does not have any effect.

  custom (byte): custom character to set, encoded in abcdefgp format.

• update()

  • display.update()

  Show on the display the stored value. For multiplexed drive, this must be called in a loop; for static drive, the value is shown until update()/clear()/show() is called.

  display (ShiftDisplay): object where function is called.

• clear()

  • display.clear()

  Hide the display content, without erasing stored value.

  display (ShiftDisplay): object where function is called.

• show()

  • display.show(time)

  Show on the display the stored value, for the given time, then clear. Blocking function.

  display (ShiftDisplay): object where function is called.

  time (long): duration in milliseconds to show the value; exact time showing will be an under approximation.

Types

• DisplayType: COMMON_ANODE, COMMON_CATHODE

• DisplayDrive: MULTIPLEXED_DRIVE, STATIC_DRIVE

• Alignment: ALIGN_LEFT, ALIGN_RIGHT, ALIGN_CENTER

Notes

• Common Anode & Common Cathode

TODO

• Multiplexed Drive & Static Drive

TODO

• abcdefgp format

TODO

• Decoupling capacitor

TODO

• Commercial Display Modules

TODO

Changelog

• master ()
  • NEW: added static drive
  • NEW: added clear() function
  • NEW: leading zeros in set(number) functions
  • NEW: support for commercial display modules (fix for issue #1)
  • CHANGE: every set(number) functions has the same possible args
  • CHANGE: default decimal places is now 1
  • CHANGE: renamed show() to update() and changed its behaviour
  • CHANGE: display type constants changed from int to DisplayType
  • CHANGE: renamed setDot() and setDotAt() to changeDot() and changeDotAt()
  • CHANGE: dot value is now optional in above functions
  • CHANGE: renamed setCustom() and setCustomAt() to changeCharacter() and changeCharacterAt()
  • CHANGE: deprecated show(value, time) for simplicity sake
  • CHANGE: alignment is now a type
  • DOC: removed 74HC595 references because it works with other shift registers
  • DOC: added argument types
  • DOC: added custom types
  • DOC: differentiate between numbers and text in set()
  • DOC: square brackets for optional args
  • DOC: example for sectioned display
  • FIX: compiler warnings
• 3.6.1 (17/9/2017)
  • DOC: improved README
• 3.6.0 (15/9/2017)
  • NEW: sectioned display feature
  • NEW: setAt() function
  • NEW: setDot() function
  • NEW: setDotAt() function
  • NEW: setCustom() function
  • NEW: setCustomAt() function
  • FIX: decimal point would not show in double value at display index 0
  • DOC: reviewed code comments
• 3.5.0 (8/9/2017)
  • Feature: set/show characters array with dot array
  • Feature: set/show custom characters
• 3.4.0 (6/9/2017)
  • Feature: loadDots() function
  • Change: print(time, value) updated to show(value, time)
  • Change: insertPoint() and removePoint() updated to insertDot() and removeDot()
  • Documentation: small fixes
• 3.3.3 (30/3/2017)
  • Change: updated contact details
• 3.3.2 (6/1/2017)
  • Change: faster show() function
  • Bugfix: better non-Arduino support (eg. attiny)
• 3.3.1 (18/12/2016)
  • Bugfix: Countdown example
• 3.3.0 (18/12/2016)
  • Feature: insertPoint() function
  • Feature: removePoint() function
  • Change: removed punctuation characters
• 3.2.3 (26/11/2016)
  • Bugfix: decimal point not showing in common anode displays
• 3.2.2 (25/11/2016)
  • Documentation: website
• 3.2.1 (24/11/2016)
  • Documentation: explain examples
• 3.2.0 (22/11/2016)
  • Bugfix: default alignments
  • Change: float/double function alignment without decimalPlaces obligation
• 3.1.0 (21/11/2016)
  • Bugfix: float/double functions problems with 0.x and -0.x
  • Bugfix: common anode display initiates unclear
  • Feature: new constructor with default pins
  • Feature: punctuation characters
  • Change: small improvements
• 3.0.1 (19/11/2016)
  • Bugfix: float/double functions not working
  • Bugfix: show/print functions exceeding time
• 3.0.0 (17/11/2016)
  • Code rewriting: performance and behavior improvement
  • Change: function signatures
  • Feature: buffer
  • Documentation: new examples
  • Documentation: updated images
• 2.2.0 (14/07/2015)
  • Feature: minimal print function
  • Feature: exit left/right animation
• 2.1.0 (03/07/2015)
  • Feature: center alignment
• 2.0.0 (23/06/2015)
  • Code refactoring
  • Full and lightweight versions
  • Feature: left and right alignment
• 1.0.0 (26/05/2015)
  • Initial release

TODO

• [ ] Finish README Notes section
• [x] Example for sectioned display
• [ ] Example for custom characters
• [ ] Example for commercial display module
• [ ] Example for static drive
• [ ] Schematics for static drive
• [ ] Remove display max size for static drive

Contacts

• https://github.com/MiguelPynto/ShiftDisplay/
• https://twitter.com/MiguelPynto
• miguelpynto@outlook.com