SevenSegmentTM1637 Arduino Library

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Arduino library for controlling a TM163x based 7-segment display module. These modules are sold under various names by various suppliers. For example:

• Seed Studio: Grove 4 digit display
• Ebay: 4 Bits Digital Tube LED TM1637
• DealExtreme: LED 4-Digit Display Module

They come in different sizes, colors and there is a clock (with a colon) and decimal (with four decimal dots) display variant. But the most common one is the red 0.36" clock version, this is also the cheapest one (you can get those for about $1.50). I've written this library using the above module, if I get my hands on any of the other variants I might add some specific code, for example to print floats on the decimal version.

Hardware setup

TM1637 PIN	Arduino PIN	Description
CLK	Any digital pin	Clock
DIO	Any digital pin	Digital output
VCC	5V	Supply voltage
GND	GND	Ground

Installation

Like any other Arduino library this library is installed by copying the files into a directory on the Arduino IDE search path. Most common is to put all files in a director in your sketch folder/libraries/SevenSegmentTM1637/. See installing additional Arduino libraries for more information.

Usage

This library uses the LCD API v1.0 so you can use the same functions/methods using this library as any lcd library which conforms to the LCD API. Furthermore this library (like described in the LCD API) inherent the Print class (See Serial.print() and for more details Print.h). This means that you can use all Print class functions/methods like you're used to when you're doing Serial.print("Something") or Serial.print(128, BIN) for example.

Basic methods

• SevenSegmentTM1637(clkPin, dioPin)Creates a display object
• init() Initializes the display
• print(value) Prints anything to the display (e.g. a string, number..)
• clear() Clears the display (and resets cursor)
• home() Resets cursor
• setCursor(row, col) Set the cursor to specified position
• setBacklight(value) Sets the brightness of the display
• on() Turn the display on (set brightness to default)
• off() Turns the display off (set brightness to zero)
• blink() Blinks what ever is on the display
• setColonOn(bool) Sets the colon in the middle of the display
• setPrintDelay(time) Sets the delay when printing more than 4 characters

Advanced methods

• encode() Encodes a single digit, single char or char array (C string)
• printRaw() Prints raw byte(s) to the display
• command() Sends one or more raw byte commands to the display

Low level methods

• comStart() Serial communication start command
• comWriteByte(bytes) Serial communication send byte command
• comAck() Serial communication get acknowledged command
• comStop() Serial communication stop command

If you still want or need more functionality, I've included two super classes:

• SevenSegmentExtended() Extends the base class with more usefull functions.
• SevenSegmentFun() Even more extensions for fun.

If you use any of these super classes, you will also get all the basic, advanced and low level methods as well. If you use the fun class extension you will get the extended class methods as well.

Extended class extra methods

• SevenSegmentExtended(clkPin, dioPin) Creates a display object
• printTime(hour, min, [blink], [blinkDelay]) Prints the time to the display
• printTime(time, [blink], [blinkDelay]) Prints the time to the display
• printDualCounter(leftValue, rightValue) Prints two digits to the display

Fun class extra methods

• SevenSegmentFun(clkPin, dioPin) Creates a display object
• printLevelVertical(level, [leftToRight]) Print 0-100% (2 steps per digit) vertical level e.g. volume, battery
• printLevelVertical(level, leftToRight, symbol) Print 0-100% (1 step per digit) vertical level using custom symbol
• printLevelHorizontal(levels[]) Prints 4 horizontal levels e.g. equalizer
• scrollingText() Prints text and (keeps) scrolling
• snake() Classic snake demo
• nightrider() Nightrider Kit demo
• bombTimer() Count down a (bomb) timer
• bouncingBall() Bouncing ball demo

For more extended information on what arguments all above functions accept and return see the header files of the classes (SevenSegmentTM1637.h, SevenSegmentExtended.h and SevenSegmentFun.h).

Trouble shooting

• Some boards might not have enough power on their 5V pin. In that case try to use an external 5V power supply. People reported that the ESP8266 might be one of those boards.

Todo

• Refactor library to make it more modular and support more chips
  • Add support for all TM16xx chips (most should already work)
  • Add support for MAX7219 displays
  • Add support for TM74HC595 displays

Changelog

• 09-07-2020 version 1.1.1
  • Bug fixes
    • fixed a typo in SevenSegmentFun.h file
• 04-07-2020 version 1.1.0
  • Improved printLevelVertical() using pablo-lp suggestions
    • The default printLevelVertical() can diplay twice the number of levels now (e.g. 9 levels for a defaulf 4 digit display)
  • Add configurable blink delay when using the printTime methods (thanks to simoneluconi)
  • Added a new printNumber() method to make it easier to print right aligned numbers
    • Thanks dan2600, Bilick88, jasonacox for your suggestions.
  • Bug fixes
    • Merge PR from berendkleinhaneveld to fix some compiler warnings
    • Merge PR from facelessloser Remove some Serial.prinln() calls
    • Merge PR from RAnders00 Fix incorrect repsonse from comReadByte()
    • Merge PR from per1234 Use correct separator in keywords.txt
• 04-11-2016 version 1.0.4
  • Fixed bombTimer not counting down to zero (thanks to foons for opening an issue)

• 22-05-2016 version 1.0.3

• add support for all AVR MCU's (thanks to per1234)

• 08-05-2016 version 1.0.2
  • fixed digitalHigh() macro for non AVR boards (thanks to per1234)
• 28-09-2015 version 1.0.1
  • fixed folder structure to comply with Arduino library 1.5 rev 2 specifications
• 28-09-2015 version 1.0.0
  • First release

Note

I spend quite a bit of time to build this library. I hope it will be useful to others. I decided to publish it, although there still might be small bugs. If you find one, just let me know and I will try to fix it. If you have any other suggestion, don't hesitate to contact me.

Sources

I've looked at many sources while constructing this library, bassicly all alternative Arduino TM1637 libraries and some AVR TM1637 libraries. While doing so I've found some really nice improvements compared to other implementations. For example, most libraries use a really low clock speed (~50us), I've tested with clock speeds as low as 1us and the chip still seems to respond well. Furthermore, from the (Chinese) datasheet it seems that you always have to perform three operation when communicating with the IC; set some configuration, set the address and send 1-4 digit data and set the display brightness. I've found out that this is not the case, you can do all of those separately if you want.

Still without all these fine examples it would have taken me a lot more time to figure out the inner workings of this IC!

Sources:

• http://blog.3d-logic.com/2015/01/21/arduino-and-the-tm1637-4-digit-seven-segment-display/
• http://www.arduino.md/hardware/lcd-and-leds/0-36-led-display-4-digit-red/
• https://brainy-bits.com/tutorials/4-bits-7-segment-led-display-with-arduino/

Keywords

People will probably Google for keywords when looking for a driver, so here are some:

TM1637 TM1636 library Arduino Led Driver 4 Digit Bits Digital LED Tube module LCD API Print.h Print class API display LCD AVR Atmega