Scroll String Only On Second Line Using 2x16 LCD

Question

I'm trying to scroll a string in the second row of the LCD while letting the string on the first row stay intact. I use Serial to run that part of the code as you can see. It work at first but when I try to make it run again it doesn't display anything on the second row.

I borrowed the code from :

http://code.nishantarora.in/arduino-lcd-projects/src/3f10686e7464665c5c59d7be772c00af7a4a93e8/scrollOneLine/scrollOneLine.ino?at=master

And made some changes:

// include the library
#include <LiquidCrystal.h>

// init the lcd display according to the circuit
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

// it's a 16x2 LCD so...
int screenWidth = 16;
int screenHeight = 2;

String line1;
String line2;

int stringStart, stringStop = 0;
int scrollCursor = screenWidth;

String CompleteString;
String stringArray[] = {"s=Plane", "i=Car", "h=Boat", "u=Rocket", "d=Jet",  "p=Submarine", "l=Truck", "b=Bicycle", "m=Skate", "enter=Train"};

String string1 = "String";

int countMovement=0;
int arraylimit = 9;

void setup() {

   lcd.begin(screenWidth,screenHeight);
   Serial.begin(9600);

}

void loop(){

   char ser = Serial.read();

   if ( ser == 'c' ) {  
     CompleteString="";

     for (int i = 0 ; i <= arraylimit; i++) {
        CompleteString += stringArray[i] + " "; // Convert String Array To Single String
     }

     roop(string1,CompleteString);
  }

}

void roop(String line1, String line2) {

  countMovement = 0;

  while ( ( countMovement ) < (line2.length() + screenWidth )  ) {

     lcd.setCursor(scrollCursor, 1);
     lcd.print(line2.substring(stringStart,stringStop));
     lcd.setCursor(4, 0); // 1 = word eat array of words very cool
     lcd.print(line1);
     delay(300);
     lcd.clear();

     if(stringStart == 0 && scrollCursor > 0){
        // Serial.println(scrollCursor);     
        scrollCursor--;
        stringStop++;
     } else if (stringStart == stringStop){
        stringStart = stringStop = 0;
        scrollCursor = screenWidth;
     } else if (stringStop == line1.length() && scrollCursor == 0) {
        stringStart++;
     } else {
       stringStart++;
       stringStop++;
     }

     countMovement++;

  }

  lcd.setCursor(4, 0);
  lcd.print(line1);

}

From what I can see using Serial as debugging is that the problem resides in the function "roop" and in specific the line:

 if(stringStart == 0 && scrollCursor > 0){

It seems that the statement is being pass on and so it doesn't move the string as it's suppose to. I could be wrong but placing a Serial call in there yields no result the second time the function is called but the first time it did.

Any help would be much appreciated! And I know the community will be grateful too since it's difficult from what I can see in post to achieve this and make it autonomous so that no big modifications needs to be done.

Answer 1

You need to reset the stringStart, stringStop and scrollCursor at the beginning of the roop function.

void roop(String line1, String line2) {

  countMovement = 0;
  stringStart = 0;
  stringStop = 0;
  scrollCursor = screenWidth;

  ...

I think you also need to move the lcd.clear up. Or else the screen will be blanked when the roop function is done scrolling.

...

  while ( ( countMovement ) < (line2.length() + screenWidth )  ) {

     lcd.clear();
     lcd.setCursor(scrollCursor, 1);
     lcd.print(line2.substring(stringStart,stringStop));
     lcd.setCursor(4, 0); // 1 = word eat array of words very cool
     lcd.print(line1);
     delay(300);

...

Answer 2

The answer from the user Gerben worked perfect. So I'll be posting another solution I came upon and the one from my original question for feature reference.

Original Code:

// include the library
#include <LiquidCrystal.h>

// init the lcd display according to the circuit
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

// it's a 16x2 LCD so...
int screenWidth = 16;
int screenHeight = 2;

String line1;
String line2;

int stringStart, stringStop = 0;
int scrollCursor = screenWidth;

String CompleteString;
String stringArray[] = {"s=Plane", "i=Car", "h=Boat", "u=Rocket", "d=Jet", "p=Submarine", "l=Truck", "b=Bicycle", "m=Skate", "enter=Train"};
String string1 = "String";
boolean ArrayRead = true;
int countMovement=0;
int arraylimit = 9;

// most of the part is pretty basic
void setup() {

   lcd.begin(screenWidth,screenHeight);
   Serial.begin(9600);

}

void loop(){

   char ser = Serial.read();

   if ( ser == 'c' ) {  
      CompleteString="";

      for (int i = 0 ; i <= arraylimit; i++) {
         CompleteString += stringArray[i] + " "; // Convert String Array To Single String
      }

      roop(string1,CompleteString);
   }

}

void roop(String line1, String line2) {

   countMovement = 0;
   stringStart = 0;
   stringStop = 0;
   scrollCursor = screenWidth;

   while ( ( countMovement ) < (line2.length() + screenWidth )  ) {

      lcd.clear();
      lcd.setCursor(scrollCursor, 1);
      lcd.print(line2.substring(stringStart,stringStop));
      lcd.setCursor(5, 0); // 1 = word eat array of words very cool
      lcd.print(line1);
      delay(300);
      lcd.clear();
      if(stringStart == 0 && scrollCursor > 0){     
         scrollCursor--;
         stringStop++;
      } else if (stringStart == stringStop){
         stringStart = stringStop = 0;
         scrollCursor = screenWidth;
      } else if (stringStop == line1.length() && scrollCursor == 0) {
         stringStart++;
      } else {
         stringStart++;
         stringStop++;
      }

      countMovement++;

   }

   lcd.setCursor(4, 0);
   lcd.print(line1);

}

The other code provided by the user "HazardsMind" for I2C LCD Module: The changes made are Serial communication and adapted for the 6 pin LCD Module.

// include the library
#include <LiquidCrystal.h>

// init the lcd display according to the circuit
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

//char * SerialComm[70];
//{"s = Plane i=Car h=Boat u=Rocket d=Jet p=Submarine l=Truck b=Bicycle m=Skate enter=Train"};

#define N_CHARS  ((sizeof(MessageOut)/sizeof(MessageOut[0]))-1)
#define N_CHARS2  ((sizeof(MessageOut2)/sizeof(MessageOut2[0]))-1)

//int len = strlen(SerialComm);

char MessageOut[30];
char MessageOut2[30];



int index = 19, index2 = 0;
unsigned long oldTime = 0, oldTime2 = 0;

byte indexer = 0; // Index into array; where to store the character
char inData[58]; // Allocate some space for the string
char inChar; // Where to store the character read



void setup()
{
   Serial.begin(9600);
   lcd.begin(16, 2);                      // initialize the lcd  
}

void loop() 


  while(Serial.available() > 0) // Don't read unless
                                              // there you know there is data
  {
      if(indexer < 57) // One less than the size of the array
      {
         inChar = Serial.read(); // Read a character
         inData[indexer] = inChar; // Store it
         indexer++; // Increment where to write next
         inData[indexer] = '\0'; // Null terminate the string
      }
  }
  // Now do something with the string (but not using ==)

  // Serial.print(inData);
  setHeadingRight("Royal", 0, 500);
  setHeadingLeft(inData, 1, 500);

  //setHeadingRight("Hello Welcome", 0, 1000); // message, row, duration
  // setHeadingLeft("Welcome", 1, 500);
}

void setHeadingRight(char * msg, byte row, unsigned long duration) 
{
   strncpy(MessageOut, msg, sizeof(MessageOut));
   if(millis() - oldTime > duration) // check the difference of the current time "millis()" to the previous time "oldTime" against the duration you want.
   {
      oldTime = millis(); // update oldTime with the current time
      if(index >= 0) // make sure the index does not go under 0
      { 
        index--; // decrecment index by 1
        for (int i = 0; i < N_CHARS; i++) // this part here displays the message on the display
        {
           lcd.setCursor(i,row); // set the column to show the element in the array
           if(index == N_CHARS) index = 0; // set index back to 0 if the index has reached the arrays max size.

              if(MessageOut[index++] != NULL) // if the element @ index is anything but NULL, show it.
                  lcd.print(MessageOut[index-1]);
              else 
                  lcd.print(' '); // if the element @ index is NULL, display a space.   
        }
      }
   else index = 19; // if index is less than 0, then set it back to 19
 }
}

void setHeadingLeft(char * msg, byte row, unsigned long duration2) 
{
  strncpy(MessageOut2, msg, sizeof(MessageOut2));
  if(millis() - oldTime2 > duration2)
  {
     oldTime2 = millis();
     if(index2 < 20) // check to see if index2 is under the array max size
     {
        index2++; // increment index
        for (int i = 0; i < N_CHARS2; i++) // same as above
        {
           lcd.setCursor(i,row);
           if(index2 == N_CHARS2) index2 = 0;

              if(MessageOut2[index2++] != NULL)
                 lcd.print(MessageOut2[index2-1]);
              else 
                 lcd.print(' ');    
              }
           }
           else index2 = 0; // otherwise set it back to 0
     }
}