lcd.print and 2D arrays

Question

Click here to see my program running

I have created a 2D array (see my full code below), and each row contains one state of a battery here is a schematic :

row [0] : "▯▢▢▷" // this row represents an empty AAA battery 
row [1] : "▮▩▢▷"
row [2] : "▮▩▩▷"
row [3] : "▮▩▩ ▶" // this row represents a Full AAA battery 

Each "▩" character is a custom made character with this function:

lcd.createChar(0, customLcdfont_squareONE);

As you saw in my video it works at the end, but it's absolutely not the way I want it to work. The code that works is a mess!

I think the problem is that the Raw n°1 ([0]) starts with a 0, (try it out it's very strange). If we replace

char batteryFonts [10][5] = {
 { 0, 1, 1, 2 }, // you see { this "0", 1, 1, 2 }, is a problem I think 
 { 3, 1, 1, 2 },
 {etc}, }
lcd.print( batteryFonts[0]); // this sentence does not work

with

"char batteryFonts [10][5]={{ 4, 1, 1, 2 }, // 4 or what ever you want 
 {etc}, 
 {etc}, }
 lcd.print( batteryFonts[0]); // this sentence behind does work, but only with a row that does not start with a 0. Why?

It works!

Here is my full code. Just connect the pins 12, 13, 7, 4, 3, 2 to the LCD.

//This is a simple program that charges alkaline batteries 
//Copyleft
#include <LiquidCrystal.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 13, 7, 4, 3, 2); // why pin 13 and not 12 ? because I love the led attached to it <3
// the empty battery - end 
byte customLcdfont_A [8] = { // B stand for "Binary" and then the pixel ... 
B01111,
B11000,
B10101,
B10100,
B10100,
B10100,
B11000,
B01111
// the empty battery body with fancy graphics enabled
};
byte customLcdfont_B [8] = { // B stand for "Binary" and then the pixel ... 
B11111,
B00000,
B11001,
B00000,
B00000,
B00000,
B00000,
B11111
};
// the empty battery + end
byte customLcdfont_C [8] = { // B stand for "Binary" and then the pixel ... 
B11100,
B00100,
B10111,
B00101, 
B00111,
B00111,
B00100,
B11100
};
// the full battery - end
byte customLcdfont_D [8] = { // B stand for "Binary" and then the pixel ... 
B1111,
B11111,
B10110,
B10111,
B10111,
B10111,
B11111,
B1111
};
// the FULL battery + end
byte customLcdfont_E [8] = { // B stand for "Binary" and then the pixel ... 
B11100,
B11100,
B01111,
B11101,
B11111,
B11111,
B11100,
B11100
};
// the full battery body
byte customLcdfont_F [8] = {
B11111,
B11111,
B00110,
B11111,
B11111,
B11111,
B11111,
B11111
};
// the 1/3 battery body 
byte customLcdfont_G [8] = {
B11111,
B11000,
B00001,
B11000,
B11000,
B11000,
B11000,
B11111
};
// the 2/3 battery body 
byte customLcdfont_H [8] = {
B11111,
B11110,
B00111,
B11110,
B11110,
B11110,
B11110,
B11111
};
/**************************************************************************/
void setup() {
 int i = 0 ; 
 // initialize serial communications at 9600 bps:
 lcd.createChar(0, customLcdfont_A);
 lcd.createChar(1, customLcdfont_B);
 lcd.createChar(2, customLcdfont_C); 
 lcd.createChar(3, customLcdfont_D);
 lcd.createChar(4, customLcdfont_E);
 lcd.createChar(5, customLcdfont_F);
 lcd.createChar(6, customLcdfont_G);
 lcd.createChar(7, customLcdfont_H);
 lcd.begin(16, 2); 
// WATCH HERE IS THE PROBLEM !!!!
//the char table behind creates my different battery states as shown in the video ;) 
 char batteryFonts [10][5]={
 { 0, 1, 1, 2 }, // this is an empty one f%*# this does not work !!!
 { 3, 1, 1, 2 },
 { 3, 6, 1, 2 },
 { 3, 7, 1, 2 },// this is a 50 % full charged battery ! 
 { 3, 5, 1, 2 },
 { 3, 5, 6, 2 },
 { 3, 5, 7, 2 }, 
 { 3, 5, 5, 2 },
 { 3, 5, 5, 4 },// this is nice full one 
 };
 // this sentence behind does not work !!! but only with the raw [0]
 lcd.print( batteryFonts[0]); // I F***ing want this to display the first raw !!!! 
 lcd.setCursor(0,1 );
 lcd.print(" not working ");
 lcd.setCursor(0,0 );
 delay(9300); // this make a short pause for us so that we can see the result
lcd.setCursor(0,1 );
 lcd.print(" working ");
 lcd.setCursor(0,0 );
 for (i=0; i=10 ; i+=1 ){
 delay(300);
 lcd.setCursor(6,0 );
 lcd.write(byte(0)); lcd.write(byte(1)); lcd.write(byte(1)); lcd.write(byte(2));
 delay(700); // batterry 0/8 empty aka discharged
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(1)); lcd.write(byte(1)); lcd.write(byte(2));
 delay(1000); //batterry 1 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(6)); lcd.write(byte(1)); lcd.write(byte(2));
 delay(1000);//batterry 2 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(7)); lcd.write(byte(1)); lcd.write(byte(2)); //batery 3 /8
 delay(1000);
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(5)); lcd.write(byte(1)); lcd.write(byte(2));
 delay(1000); //batery 4 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(5)); lcd.write(byte(6)); lcd.write(byte(2));
 delay(1000); //batery 5 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(5)); lcd.write(byte(7)); lcd.write(byte(2));
 delay(1000); //batery 6 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(5)); lcd.write(byte(5)); lcd.write(byte(2));
 delay(1000); //batery 7 /8
 lcd.setCursor(6,0 );
 lcd.write(byte(3)); lcd.write(byte(5)); lcd.write(byte(5)); lcd.write(byte(4)); //batery 8 /8
 delay(1000); 
 }
 lcd.setCursor(15, 1);
 delay(115000);
}
/**************************************************************************/
void loop() {
//This is not interesting here 
 lcd.print(" ~ The end of the code ... thank you for reading ;) ~ ");
}

Answer 1

You are correct; in C a NUL (0x00) is used to indicate the end of a char*. You will need to use LiquidCrystal::write() in order to send the character data byte by byte instead of depending on LiquidCrystal::print() to handle it.

Also, consider moving all of that static data into flash; you're going to need to handle it manually so you may as well do it right in the first place.

• Thundercoal: This confirms my doubs ! It's sloppy isn't it ? It's the same as in the C89 I studied, but slightly uncomfortable and I think the arduino compiler should be updated to avoid this "issue"
• Ignacio Vazquez-Abrams: It has nothing at all to do with the compiler. It is a fundamental tenet of C/C++, and LiquidCrystal::print() adheres to it.
• Thundercoal: Oh realy ? So I should study more !
• Thundercoal: I don't say thanks... as the comment box told me to avoid to say thanks (y) But I realy want to !
• Ignacio Vazquez-Abrams: It's okay, your sentiment has reached me.