TM1638 Scrolling text on Arduino

The following explanation of the code and how it works and how to connect TM1638
(with led array, display and button array) to Arduino.
For IDE and project Initialization I used PlatformIO and due to that and since it makes lots of stuff easier it generates project in C++ with lots os useful configs pre-prepared and if your using Git you will find already prepared .git-ignore file in project as well.

Video example:

Code explanation:

In following code you can see the imports which I used, from Arduino lib which you can ignore if you are using Native IDE.
Regarding TM1638.h you can get it on THIS Github and add it in Platformio under lib or in native IDE under libraries folder.

#include "Arduino.h"
#include <TM1638.h>

Now comes the variable initialisation part.
As seen on the video we connect the wires to 8,9,10 pins on TM1638 with TM1638 module(8, 9, 10); command.
For default interval I have chosen 1000ms which is the rate before it moves letters one forward for scrolling.
String textScroll is a variable containing the text that will get displayed on the display.
bckp variable will be used for reinitializing the text after it scrolled through. It may not be the best way of doing it since later we are popping letters out of string, but I tried to minize the amount of code and kinda simplify it šŸ˜€
Well buttons variable should be quite obvious so let’s continue to final previousMillis variable.
This variable will be used for helping to detect button press between moving the display letters. That’s because if we would use Delay command we would be essentially stopping the clock and unable to detect button press, or a lot harder and unintuitive to detect them.

// define a module on data pin 8, clock pin 9 and strobe pin 10
TM1638 module(8, 9, 10);
long interval=1000;
String textScroll="This is long sentence";
String bckp;
byte buttons;
unsigned long previousMillis = 0;

In setup loop we only set textScroll string to bckp string variable so we can restore text after we pop up the whole string.

void setup()
{
  bckp = textScroll;
}

Start of the main loop:
In the main loop we start with setDisplayToString through which we connect to TM1638 module and set the string variable. After that we date our currentMillis to get millisecond amount which passed. We compare that in the IF statement and check if the difference is bigger then interval that is determined in the variable (P.S. later we configure interval to be adjustable). The next line is just updating previousMillis to currentMillis to reset the counter for next time.
After that we finally get to the interesting part.
In if(textScroll.length()>0 we check if string variable length is bigger than 0 and if it is then we remove the first character of the string and re-show it on display of TM1638 with clearDisplayDigitclearDisplayDigit

void loop()
{

module.setDisplayToString(textScroll);
unsigned long currentMillis = millis();

if (currentMillis - previousMillis >= interval) {
  // save the last time you blinked the LED
  previousMillis = currentMillis;
  if(textScroll.length()>0){
    textScroll.remove(0, 1);
    if(textScroll.length()<8){
      module.clearDisplayDigit(textScroll.length(), false);
    }
  } else {
    textScroll = bckp;
  }
}

The most important code of scrolling text is now over, but here is some extra code regarding turning LED’s ON with buttonsĀ and changing the interval time for text scrolling

buttons=module.getButtons();
if(buttons==1) {
  module.setLED(TM1638_COLOR_RED, 0);
  interval=500;
  delay(100);
}if (buttons==4) {
  module.setLED(TM1638_COLOR_RED, 2);
  interval=1500;
  delay(100);
}if (buttons==8) {
  module.setLED(TM1638_COLOR_RED, 3);
  interval=2500;
  delay(100);
}
module.setLED(0, 0);
module.setLED(0, 2);
module.setLED(0, 3);

}

Full code:

In code bellow you can see full united code. You can also see everything in a sample project under THIS URL in Github.

#include "Arduino.h"
#include <TM1638.h>

// define a module on data pin 8, clock pin 9 and strobe pin 10
TM1638 module(8, 9, 10);
long interval=1000;
String textScroll="This is long sentence";
String bckp;
byte buttons;
unsigned long previousMillis = 0;

void setup()
{
  bckp = textScroll;
}

void loop()
{

module.setDisplayToString(textScroll);
unsigned long currentMillis = millis();

if (currentMillis - previousMillis &gt;= interval) {
  // save the last time you blinked the LED
  previousMillis = currentMillis;
  if(textScroll.length()>0){
    textScroll.remove(0, 1);
    if(textScroll.length()<8){
      module.clearDisplayDigit(textScroll.length(), false);
    }
  } else {
    textScroll = bckp;
  }
}

buttons=module.getButtons();
if(buttons==1) {
  module.setLED(TM1638_COLOR_RED, 0);
  interval=500;
  delay(100);
}if (buttons==4) {
  module.setLED(TM1638_COLOR_RED, 2);
  interval=1500;
  delay(100);
}if (buttons==8) {
  module.setLED(TM1638_COLOR_RED, 3);
  interval=2500;
  delay(100);
}
module.setLED(0, 0);
module.setLED(0, 2);
module.setLED(0, 3);

}

By |April 24th, 2016|Categories: ALL, Electronics, How to|Tags: , , |

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Senior lead developer currently working in Java, architecture design, mix of tech from Front-end in JS and templating to chef,rundeck etc. For fun and challenge I am writing different blog posts from stories to poems, programming tutorials and many more. Currently working on my Masters degree on a part-time basis.