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.

• Thomas S.: You may add the LiquidCrystal.h/.cpp code to your project and modify it if necessary.
• DarkXDroid: Why do I need to do that? I'm almost there. I know it only needs a little bit of understanding and a simple explanation to make it work. Someone to point what's wrong in the code.

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);
...

• DarkXDroid: Seriously man that's what I was talking about! A simple mistake with an easy solution. I found another code that does the same in both directions so I'll be posting both codes for future reference. Thanks 4 your time
• Gerben: Great! Glad to have helped.

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円'; // 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
 }
}