Display 40x2 driver problem

Other Hardware Displays
1

Hi i'm trying to use a 40x2 display from a fire alarm control panel.
I wired it up like a new lcd but i get weird characters. I'm guessing the driver is not corect.


Is there anyway to identify what driver to apply?
this is the code:

/*
  LiquidCrystal Library - Hello World

 Demonstrates the use a 16x2 LCD display.  The LiquidCrystal
 library works with all LCD displays that are compatible with the
 Hitachi HD44780 driver. There are many of them out there, and you
 can usually tell them by the 16-pin interface.

 This sketch prints "Hello World!" to the LCD
 and shows the time.

  The circuit:
 * LCD RS pin to digital pin 12
 * LCD Enable pin to digital pin 11
 * LCD D4 pin to digital pin 5
 * LCD D5 pin to digital pin 4
 * LCD D6 pin to digital pin 3
 * LCD D7 pin to digital pin 2
 * LCD R/W pin to ground
 * LCD VSS pin to ground
 * LCD VCC pin to 5V
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)

 Library originally added 18 Apr 2008
 by David A. Mellis
 library modified 5 Jul 2009
 by Limor Fried (http://www.ladyada.net)
 example added 9 Jul 2009
 by Tom Igoe
 modified 22 Nov 2010
 by Tom Igoe

 This example code is in the public domain.

 http://www.arduino.cc/en/Tutorial/LiquidCrystal
 */

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

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(40, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis() / 1000);
}

Thanks.

2

I believe that Bill Perry's hd44780 library supports the 40x2 LCD display. The library is available through the library manager. You would use the hd44780pinIO class. There are examples and documentation included with the library.

If you have trouble Bill is often on the forum to answer questions and render aid.

3

While I do recommend the hd44780 library with the hd44780_pinIO class for 4 bit mode,
pretty much any "LiquidCrystal" library should be able to talk to that display.

If you are getting gobbledygook on the display, it very likely is not hooked up correctly.
It is easy to accidentally miscount the pins or get the even/odd top/bottom orientation incorrect
or get the pin orientation on the corresponding header/connector on the other and of the cable backwards.
(I've done that myself a few times)

-- bill

4

bperrybap:
While I do recommend the hd44780 library with the hd44780_pinIO class for 4 bit mode,
pretty much any "LiquidCrystal" library should be able to talk to that display.

If you are getting gobbledygook on the display, it very likely is not hooked up correctly.
It is easy to accidentally miscount the pins or get the even/odd top/bottom orientation incorrect
or get the pin orientation on the corresponding header/connector on the other and of the cable backwards.
(I've done that myself a few times)

-- bill

Thanks for the answer.
it was the R/W pin to pin 11 on the arduino.fixed to the ground and it works.