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

ShiftDisplay

by MiguelPynto

Arduino library for driving 7-segment displays using 74HC595 shift registers

• Show numbers and text
• Concatenate multiple displays as one, for a maximum of 8 digits
• Compatible with common cathode and common anode
• Only 3 pins used on Arduino

Hardware

• 1x (or more) 7-segment LED display
• 2x 74HC595 shift register
• 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 on 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--) {
		display.show(i, 400, ALIGN_CENTER); // store number and show it for 400ms
		display.setDot(1, true); // add dot to stored number
		display.show(400); // show number with dot for 400ms
	}
	display.set("GO"); // store "GO"
}

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

Reference

Constructors

• ShiftDisplay()

  • ShiftDisplay display(displayType, displaySize)
  • ShiftDisplay display(displayType, sectionCount, sectionSizes)
  • ShiftDisplay display(latchPin, clockPin, dataPin, displayType, displaySize)
  • ShiftDisplay display(latchPin, clockPin, dataPin, displayType, sectionCount, sectionSizes)

  Create a ShiftDisplay object, initialize the library using the interface pins and display properties. 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).

  display: newly created ShiftDisplay type object.

  displayType: constant COMMON_CATHODE or COMMON_ANODE, defining the type of the display.

  displaySize: quantity of digits on the display.

  sectionCount: quantity of sections on the display.

  sectionSizes: array of ints initialized with the quantities of digits for each section.

  latchPin, clockPin, dataPin: 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.

Functions

• set()

  • display.set(value)
  • display.set(value, alignment)
  • display.set(valueReal)
  • display.set(valueReal, alignment)
  • display.set(valueReal, decimalPlaces)
  • display.set(valueReal, decimalPlaces, alignment])
  • display.set(customs)
  • display.set(characters, dots)

  Store a value to show next on the display. The entire previous value is cleared.

  display: object of type ShiftDisplay.

  value: value to set, can be a number (int, long) or text (char, char array, string object); for text, valid characters are 0-9 a-z A-Z -, others are converted to a space; null-terminated char array; if is too big to fit in the display, it is trimmed according to alignment.

  valueReal: value to set, a real number (float, double); if is too big to fit in the display, it is trimmed according to alignment.

  alignment: alignment of the value or valueReal on the display; constant ALIGN_LEFT, ALIGN_RIGHT or ALIGN_CENTER; if is not specified, the default is ALIGN_RIGHT for numbers and ALIGN_LEFT for text.

  decimalPlaces: number of digits following the decimal point; if is not specified, the default is 2.

  customs: array of bytes initialized with the 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: array of chars initialized with the characters to set, each char is a character on the display, from left to right; valid characters are 0-9 a-z A-Z -, others are converted to a space; array length must match display size.

  dots: array of bools initialized with the dot values to set, each bool is a dot on the display, from left to right; bool value, true to show dot, false to hide dot; array length must match display size.

• setDot()

  • display.setDot(index, dot)

  Modify the stored value by showing or hiding a dot on the character of the specified index.

  display: object of type ShiftDisplay.

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

  dot: bool value, true to show dot, false to hide dot.

• setCustom()

  • display.setCustom(index, custom)

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

  display: object of type ShiftDisplay.

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

  custom: byte with the custom character to set, encoded in abcdefgp format.

• setAt()

  • display.setAt(section, value)
  • display.setAt(section, value, alignment)
  • display.setAt(section, real)
  • display.setAt(section, real, alignment)
  • display.setAt(section, real, decimalPlaces)
  • display.setAt(section, real, decimalPlaces, alignment)
  • display.setAt(section, customs)
  • display.setAt(section, characters, dots)

  Store a value to show next on the specified section. The previous value set for this section is cleared.

  display: object of type ShiftDisplay.

  section: number of the section on the display to set the value, starting at 0 for the first; if is invalid, function does not have any effect.

  value: value to set, can be a number (int, long) or text (char, char array, string object); for text, valid characters are 0-9 a-z A-Z -, others are converted to a space; null-terminated char array; if is too big to fit in the section, it is trimmed according to alignment.

  valueReal: value to set, a real number (float, double); if is too big to fit in the section, it is trimmed according to alignment.

  alignment: alignment of the value or valueReal on the section; constant ALIGN_LEFT, ALIGN_RIGHT or ALIGN_CENTER; if is not specified, the default is ALIGN_RIGHT for numbers and ALIGN_LEFT for text.

  decimalPlaces: number of digits following the decimal point; if is not specified, the default is 2.

  customs: array of bytes initialized with the 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: array of chars initialized with the characters to set, each char is a character on the section, from left to right; valid characters are 0-9 a-z A-Z -, others are converted to a space; array length must match section size.

  dots: array of bools initialized with the dot values to set, each bool is a dot on the section, from left to right; bool value, true to show dot, false to hide dot; array length must match section size.

• setDotAt()

  • display.setDotAt(section, index, dot)

  Modify the stored value by showing or hiding a dot on the character of the specified index of section.

  display: object of type ShiftDisplay.

  section: number of the section on the display to set the dot, starting at 0 for the first; if is invalid, function does not have any effect.

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

  dot: bool value, true to show dot, false to hide dot.

• setCustomAt()

  • display.setCustomAt(section, index, custom)

  Modify the stored value by replacing the character (and dot) at the specified index of section with a custom character.

  display: object of type ShiftDisplay.

  section: number of the section on the display to set the custom character, starting at 0 for the first; if is invalid, function does not have any effect.

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

  custom: byte with the custom character to set, encoded in abcdefgp format.

• show()

  • display.show()
  • display.show(time)

  Show stored value on the display.

  display: object of type ShiftDisplay.

  time: duration in milliseconds to show the value; if is not specified, the value is shown for a single iteration; exact time showing will be an under aproximation.

• show()

  • display.show(value, time)
  • display.show(value, time, alignment)
  • display.show(valueReal, time)
  • display.show(valueReal, time, alignment)
  • display.show(valueReal, time, decimalPlaces)
  • display.show(valueReal, time, decimalPlaces, alignment)
  • display.show(customs, time)
  • display.show(characters, dots, time)

  Store and show a value on the display. The entire previous value is cleared.

  display: an object of type ShiftDisplay.

  value: value to set and show, can be a number (int, long) or text (char, char array, string object); for text, valid characters are 0-9 a-z A-Z -, others are converted to a space; null-terminated char array; if is too big to fit in the display, it is trimmed according to alignment.

  valueReal: value to set and show, a real number (float, double); if is too big to fit in the display, it is trimmed according to alignment.

  time: duration in milliseconds to show the value; exact time showing will be an under aproximation.

  alignment: alignment of the value or valueReal on the display; constant ALIGN_LEFT, ALIGN_RIGHT or ALIGN_CENTER; if is not specified, the default is ALIGN_RIGHT for numbers and ALIGN_LEFT for text.

  decimalPlaces: number of digits following the decimal point; if is not specified, the default is 2.

  customs: array of bytes initialized with the custom characters to set and show, encoded in abcdefgp format, each byte is a character on the display, from left to right; array length must match display size.

  characters: array of chars initialized with the characters to set and show, each char is a character on the display, from left to right; valid characters are 0-9 a-z A-Z -, others are converted to a space; array length must match display size.

  dots: array of bools initialized with the dot values to set and show, each bool is a dot on the display, from left to right; bool value, true to show dot, false to hide dot; array length must match display size.

Constants

• ALIGN_LEFT
• ALIGN_RIGHT
• ALIGN_CENTER
• COMMON_ANODE
• COMMON_CATHODE

Notes

• Common Cathode & Common Anode

TODO

• abcdefgp format

TODO

• Multiplexing

TODO

• Decoupling capacitor

TODO

Changelog

• 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

• Sectioned display
• Improve README
• Example for sectioned display
• Example for custom characters
• INDIVIDUAL_CATHODE and INDIVIDUAL_ANODE display types

Contacts

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