COI - Scrolling Text

You can use the code linked at the bottom as a skeleton for your own program. Modify the appendLCD or scrollLCD code to display the text you want, and be sure to include the initLCD(); command in the setup function.

Step 1: Hardware

• Intel Edison
• Static Mat
• Computer
• 2 Mini USB Cables
• Jumper Cable
• Seeed RGB Backlight LCD

Step 2: Setup

1. Plug your Grove base shield into your Edison.
2. Plug jumper cable into I2C port (which one doesn’t matter). Plug other end into RGB Backlight LCD.
3. Download code at the end of the page.
4. Paste code into Arduino IDE.
5. Upload the code into Edison.
6. Play around with the scrolling text to see what you can create.

Step 3: Programming/Code

Download the file at the end of the instructable, or copy the following code into your Arduino-Intel IDE (Integrated Development Environment). Upload the code to the Edison Board.

//This is a library of functions designed to simplify the task of setting up scrolling code on the lcd screen
//There are several modes of text scrolling:
//Continuous scrolling - characters will scroll across the lcd screen as they are added.
//Looped scrolling - Update a String that scrolls on loop, choose the row to scroll.

#include
#include

rgb_lcd lcd;

const int lcdRows = 2;
const int lcdCols = 16;

int milisPerChar = 125;
long prevMilis = 0;

int scrollPos[lcdRows];
String prevStrings[lcdRows];

//EXAMPLE STRINGS:
String scrollingText = "This text will scroll at the specified rate on loop from right to left.";

void initLCD(){
  lcd.begin(lcdCols, lcdRows);
  for(int i = 0; i < lcdRows; i++){
    scrollPos[i] = 0;
    prevStrings[i] = " ";
    for(int j = 0; j < lcdCols - 1; j++){
      prevStrings[i] += " ";
    }
  }
  lcd.setRGB(255,255,255); //White by default, can be customized
}

void scrollLCD(int rowNum, String text){
  text = text + " ";
  if(millis() - prevMilis > milisPerChar){
    scrollPos[rowNum] += (millis()-prevMilis)/milisPerChar;
    scrollPos[rowNum] = scrollPos[rowNum] % text.length();
    prevMilis = millis();
  }

  lcd.setCursor(0,rowNum);
  for(int i = 0; i < lcdCols; i++){
    lcd.print(" ");
  }
  lcd.setCursor(0,rowNum);
  if(text.length() < lcdCols){
    lcd.print(text);
    lcd.setRGB(255,0,0);
  } 
  else {
    for(int i = 0; i < lcdCols; i++){
      lcd.print(text[(scrollPos[rowNum] + i)%text.length()]);
    }
  }
}

void appendLCD(int rowNum, String textToAppend){
  prevStrings[rowNum] = prevStrings[rowNum] + textToAppend;
  prevStrings[rowNum] = prevStrings[rowNum].substring(prevStrings[rowNum].length()-1-lcdCols, prevStrings[rowNum].length());
  lcd.setCursor(0, rowNum);
  lcd.print(prevStrings[rowNum]);
}

void setup() {
  initLCD();

  //Perform Other Initialization Steps Here:
}

void loop() {
  scrollLCD(0, scrollingText);
  if(random(4)==0){
    String alphabet = "ABCDEFGHIGJKLMNOPQRSTUVWXYZ";
    int ranVal = random(alphabet.length());
    appendLCD(1, alphabet.substring(ranVal, ranVal+1));
  }
  
  delay(100);//Unless you are doing a lot of processing, this is necessary to prevent screen flickering.
}

Step 4: Results/Lessons Learned

This product allows the user to display a long string of text on a screen that isn’t large enough to display it. It can be used for a variety of things ranging from displaying a grocery list to advertising the benefits of a product.