Error with I2C LCD

Projects Programming
1

Hey all, I am using the code exactly as shown here but I am getting the following error when trying to verify
http://arduino.cc/playground/Code/I2CPortExpanderAndLCDs

lcd_i2c.cpp: In function 'void setup()':
lcd_i2c:30: error: 'WriteLCD' was not declared in this scope

any ideas here?

2

The WriteLCD function isn't implemented. That's not your fault.

3

cool, any ideas how to fix it?

4

My guess would be to replace calls to WriteLCD with WriteLCDByte or with SendToLCD but it's just a guess. I didn't write the code.

5

that is far beyond my comprehension. How did unusable code end up on the Arduino website?

6

WindowMaker:
that is far beyond my comprehension.

Add the word "Byte" where you see the word "WriteLCD".

So WriteLCD(ADDR,'a'); would become WriteLCDByte(ADDR,'a');

WindowMaker:
How did unusable code end up on the Arduino website?

Anyone can add pages to the Playground. Maybe whoever posted that page didn't proofread their own code.

I guess a question for you is, what module are you using? Are you sure that code will work with whatever you are using?

7

thanks for the explanation. when I add Byte, it goes to this error

lcd_i2c:32: error: 'class LCDI2C4Bit' has no member named 'WriteLCDByte'

8

Change setup in the example code to read:

void setup()
{
  Serial.begin(9600);
  Wire.begin(); // join i2c bus (address optional for master)
  lcd.init();
  lcd.printIn("test");
  lcd.print('a');
  lcd.clear();
  lcd.print('c');
  lcd.cursorTo(0,0);
  lcd.printIn("0");
  lcd.cursorTo(1,0);
  lcd.printIn("1");
  lcd.cursorTo(2,0);
  lcd.printIn("2");
  lcd.cursorTo(3,0);
  lcd.printIn("3");
}

Then it compiles.

9

Yes it does! Awesome!

One final question :smiley:

How do I find the device address? I am using the MCP23008 (i have more than one running), I have A0, A1, and A2 wired to 5v so my understanding would be that the address is 0100111. Do I just put that int he brackets at Wire.begin?

here is the datasheet

10

There is a I2C scanner here:

If you have more than one MCP23008 set the A0, A1, A2 to different combinations (eg. Gnd/5V/Gnd and so on).

This is the line you change:

int ADDR = 0xA7;

Since you want (say) 3 devices you could have:

LCDI2C4Bit lcd1 = LCDI2C4Bit(0b0100000,4,20);
LCDI2C4Bit lcd2 = LCDI2C4Bit(0b0100001,4,20);
LCDI2C4Bit lcd3 = LCDI2C4Bit(0b0100010,4,20);

That way you have three instances of the class with different addresses for each one. Although I think that does an unnecessary copy operation. How about:

LCDI2C4Bit lcd1 (0b0100000, 4, 20);
LCDI2C4Bit lcd2 (0b0100001, 4, 20);
LCDI2C4Bit lcd3 (0b0100010, 4, 20);