Advice for Connecting LCD Display QP5520 (Large Display) to Arduino

Other Hardware Displays
1

Hi Guys,

I would just like to share some advice on connecting this particular type of display. I spent all day yesterday trying to get it to work. This LCD screen is not as common and has some painful differences. After troubleshooting for about 5 hours I feel like I want to share some important points you must know.

1.) This QP5520 is fully compatible with Arduino etc as it is based on the Hitachi HD44780.

2.) When you are facing the display, the pins should be visible on the bottom left (That is the correct orientation (Many posts I read, people had the display upside down)

3.) On the PCB... The pins are not in order from 1-16, (Instead... from left to right facing the display, it is (14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 15, 16).
UPDATE: As per this diagram-->> http://lavalance.com/Arduino/LCD%20DISPLAY%20QP5520%20PCB%20PIN%20ARRANGEMENT.jpg

Do not just copy this diagram http://arduino.cc/en/uploads/Tutorial/LCD_bb.png from the Arduino site. It is useful, but you need to account for the difference in pin order across the PCB.

4.) The example sketches in the liquid crystal library will not work unless you include the library SPI.h. This library is part of the Arduino IDE by default. So just include it. Disregard, My installation being wacky. Thanx Don

5.) If you see all black boxes across the top line it is most likely that your pins are not connected correctly/bad soldering.

6.) Oh, and If you can't get it to work, get a multimeter and check all you pins with traces on the board. Forget the human eye, it is their to trick you.

Let me know if you have any questions/feedback :smiley:

LCD Display QP5520 Datasheet: http://www.jaycar.com.au/products_uploaded/qp5520.pdf

2

You would never know that from the datasheet you linked but I saw the white silk screen "16",15", "1"......................"14".
So , would it be safe to say that you had an "Ah Hah !" moment when you finally saw that or did you
catch it right at the start ?

qp5520.pdf (30.3 KB)

3

When you are facing the display, the pins should be visible on the bottom left

In general the LCD modules with the connections below the display have a non standard pin-out and there are several variations.

4.) The example sketches in the liquid crystal library will not work unless you include the library SPI.h. This library is part of the Arduino IDE by default. So just include it.

Can you give any reasonable explanation for this? It sounds absurd to me.

Don

4

raschemmel:
You would never know that from the datasheet you linked but I saw the white silk screen "16",15", "1"......................"14".
So , would it be safe to say that you had an "Ah Hah !" moment when you finally saw that or did you
catch it right at the start ?

There was a slight "A-Ha" Moment, but I did have a soldered connection which was giving me grief. Multi-metre and some creativity got me through :slight_smile:

5

4.) The example sketches in the liquid crystal library will not work unless you include the library SPI.h. This library is part of the Arduino IDE by default. So just include it.

Can you give any reasonable explanation for this? It sounds absurd to me.

Don
[/quote]

Hi Don,

After downloading and installing the Liquidcrystal Library (through/from the Arduino Site) I used the "Hello World" example.
Code is as follows. I clicked verify without any changes to the sketch. which resulted in the following errors.

/*
  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
 * 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(16, 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);
}

Errors Compiling:
Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp: In member function 'void LiquidCrystal::initSPI(uint8_t)':
/Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp:117: error: 'SPI' was not declared in this scope
/Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp:120: error: 'SPI_CLOCK_DIV2' was not declared in this scope
/Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp:124: error: 'SPI_MODE0' was not declared in this scope
/Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp: In member function 'void LiquidCrystal::spiSendOut()':
/Users/lance/Documents/~Arduino/libraries/LiquidCrystal/LiquidCrystal.cpp:403: error: 'SPI' was not declared in this scope

So... I made the assumption that the Liquid crystal library references to the SPI library, and added "#include <SPI.h>" - Then when I click verify... It compiled no problem, and uploading/functioning correctly.

Does it seem absurd because the Liquid Crystal Library does not run on SPI? Im fairly new to the Arduino platform. Perhaps you could elaborate? :smiley:

  • Lance
6

So... I made the assumption that the Liquid crystal library references to the SPI library

It doesn't.

Does it seem absurd because the Liquid Crystal Library does not run on SPI?

Yes

Perhaps you could elaborate?

I just did.

I would guess that there is something messed up in your particular installation of the Arduino IDE since the LiquidCrystal library and the accompanying examples have been around for several years.

The LiquidCrystal library that you should be using is normally located with the rest of the 'official' Arduino libraries not in your 'Documents' folder which is where 'add-on' libraries typically reside.

Don