Simple, but not geting there yet - Text strings

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hi there,

Been reading this forum for a while. Got my arduino and love it.
Got my LCD working. But now want to improve it.
I have 16 chars in my LCD, but I want to display 24... hum.. scroling I thought!

Since the text I wana scroll is in byte variables, I first must convert them in to text, and the add it to a string to scroll in the LCD, Right?

Well it's easier to say than do... :frowning: Heeelppp Please :S

#include <LCD4Bit_mod.h> 

byte second=0;
byte minute=0;
byte hour=0;
byte dayofweek=1;
byte day=1;
byte month=1;
byte year=10;


void setup(){
  
    Serial.begin(19200);
 lcd.init();
 lcd.clear();
 lcd.printIn("***LCD ON***");
 delay(200);

}



void loop(){

char* dias [] ={" Domingo"," Segunda"," Terça"," Quarta"," Quinta"," Sexta"," Sábado"};
      
//day=0; RTC returns days as 0 to 7, Sunday, Monday..etc.



char temp="";
char MESSAGE[24];

sprintf(MESSAGE, "%i:%i %c %i-%i-%i", hour,minute, dias[dayofweek],day,month,year);
//  Desired result line below
// char MESSAGE[] = "12:12 Segunda 01-10-2010";





int MESSAGE_LENGTH = sizeof(MESSAGE) - 1;
const int DISPLAY_WIDTH = 15;
int g_nPosition = 0;

  int i;
     if(g_nPosition < MESSAGE_LENGTH - DISPLAY_WIDTH)
     {
           for(i=0; i<DISPLAY_WIDTH; i++)
           {
            lcd.cursorTo(i, 0);                 
            lcd.printIn(MESSAGE[g_nPosition + i]);
           }
     }
     else
     {
           int nChars = MESSAGE_LENGTH - g_nPosition;
           for(i=0; i<nChars; i++)
           {

            lcd.cursorTo(i, 0);                 
            lcd.printIn(MESSAGE[g_nPosition + i]);
           }

           for(i=0; i<(DISPLAY_WIDTH - nChars); i++)
           {
            lcd.cursorTo(i, 0);                 
            lcd.printIn(MESSAGE[g_nPosition + i]);
           }
     }

     g_nPosition++;
     if(g_nPosition >= MESSAGE_LENGTH)
     {
           g_nPosition = 0;
     }

     delay(500);
     
}

For now waiting to get home after work and see where we stand.. eehehhe :slight_smile:

2 
char temp="";
char MESSAGE="";

Can't assign a string to a char.. Reserve space with something like:

char MESSAGE[24];

temp=char(hour);

Casting from byte to char doesn't do much for you here (both are 8-bit, only difference is that char can be negative). Take a look at sprintf

3

Anyone tried this yet?

Looks to have been added in v0019 and supports substring() which would make extracting parts of the string much easier.

4

The listed functionality appears to be the same as the String library available for 0018.

5

Meh. I never even knew that existed... how much easier my recent life would have been if I only I'd known. IF ONLY...

:stuck_out_tongue:

6

Thank you all for the tips :slight_smile:

drhex
Sprintf is a good solution. ;D

But now, is the sintax somethig like this?
temp=sprintf(MESSAGE, "%b:%b %c %b"-"%b"-"%b", hour,minute, dias[dayoftheweek],day,month,year);

:-?

// char MESSAGE[] = "12:12 Segunda 01-10-2010"; // Desired result :slight_smile:

Does sprintf handle byte with %b as %i for int ?

7

%b is not a valid format specifier. Use %i.

8

Thanks PaulS.

Notice that I'm using a byte to adress the index of the days variable. Is this alowed? doesn't it have to be a int?

9

Implicit casting will be performed whenever necessary. When the cast is from a smaller data type (byte) to a larger data type (int), the cast will always succeed, with no loss of information (as long as the same modifiers (signed/unsigned, etc.) are used.