lcd display not working arduino quotation

This stems from the fact that the LCD controller itself does not inherently support the function and in fact treats the ASCII codes for and as displayable characters instead of control codes.

The fact that the LiquidCrystal library inherits from Print class and thus permits the use of println() essentially makes things worse. Instead of barfing and spitting out an error message it just happily displays two unrelated characters on the screen and the uninitiated have no idea of the cause.

In my opinion the basic LiquidCrystal library should concentrate on implementing all of the capabilities of the LCD controller and no more. If people want a library that more closely emulates a CRT (or LCD) terminal that is fine, but I think it should be done in a different library.

It"s 16x2, i"ve written some code to print out text but the only thing that appears is the top row filled with boxes and the bottom row showing nothing..

I"ve read another forum talking about setting the LCD baud rate to my serial monitor rate, but i"m not sure how to do any of that. this is the product i bought: OSEPP - Multi Colored LED Assortment Set

My normal answer would be that you can use any available Arduino I/O pin for any of the LCD control or signal lines, but that is only true when you are doing the wiring between the two devices.

In this case the original poster did not tell us that he was using a shield. In that case the wiring between the two devices has already been done and your constructor (LiquidCrystal lcd(...)) must match that wiring.

Unfortunately this is one of the "bodgie" shields for which the warning at the top of this forum applies. It is all right as long as you never make pin 10 an output and write it HIGH - which also means you must not include it in the descriptor.

Unfortunately this is one of the "bodgie" shields for which the warning at the top of this forum applies. It is all right as long as you never make pin 10 an output and write it HIGH - which also means you must not include it in the descriptor.

Posting a monstrously huge picture is not necessary and posting any picture without specifying the code that produced it is usually a waste of time and bandwidth.

Posting a monstrously huge picture is not necessary and posting any picture without specifying the code that produced it is usually a waste of time and bandwidth.

(1) If the module has a backlight then get it working properly. This involves only pins 15 and 16 on most LCD modules. Make sure to use a current limiting resistor if there is none on the LCD module.

(2) Get the power and contrast working properly. This involves only pins 1, 2, and 3 on most LCD modules. You should be able to just barely see blocks on one row of a two row display and on two rows of a four row display.

NOTE: The Arduino has not been used yet, except as a possible source for the power needed for the first two steps. Do not try to go any further until this is working. If you don"t see the blocks then no amount of program code will help.

If you get a display but it is garbled or has some other problems then try again with a "static" sketch, one that displays a simple message on the top row of the display and then stops. All of your code should be in setup() and loop() should be empty between the brackets.

If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module. We also need a copy/paste version of the code that you are actually using, not a link to the code that you think you are using.

In 4 bit mode, the host and the LCD must remain in nibble sync. If they lose nibble sync with each other, it will never recover so the LCD will start to see garbage commands.

So if the library is in 4 bit mode and you power cycle only the LCD, the host (arduino) and the LCD will not be in the same mode (LCD in 8 bit mode, host in 4 bit mode) and the LCD will see garbage commands.

In 8 bit mode, it is still possible to get glitches on the display, but since things are done byte at a time there is no nibble synchronization issue so any effects of noise should be short lived and future commands to the LCD should continue to work.

For an I2C LCD display to work, the I2C address and the I2C backpack to LCD pin mapping must be correct. If the library default settings for either or both are not correct the LCD will not work. You can try to figure out the right pin mapping and use an I2C scanner to find the address, but if you install and use the hd44780 library that is done automatically by the library.

Install the hd44780 library. The hd44780 library is the best available for I2C LCDs. The library is available in the Library Manager. Go to Library Manager (in the IDE, Sketch, Include Libraries, Manage Libraries) and in the Topics dropdown choose Display and in the Filter your search box enter hd44780. Select and install the hd44780 library by Bill Perry.

The class that you want to use is the hd44780_I2Cexp class. There are examples to show how to use the library. The nice thing about the hd44780 library is that it will autodetect the I2C address and the I2C backpack to LCD pin mapping.

In the examples, there is a diagnostic sketch that will help us to help you if you still have trouble with the display. Run the diagnostic sketch and post the results.

Also there is the contrast adjustment, usually a small blue trimpot on the I2C expander backpack. If that is not adjusted properly the display will show nothing or just boxes.

This stems from the fact that the LCD controller itself does not inherently support the function and in fact treats the ASCII codes for and as displayable characters instead of control codes.

The fact that the LiquidCrystal library inherits from Print class and thus permits the use of println() essentially makes things worse. Instead of barfing and spitting out an error message it just happily displays two unrelated characters on the screen and the uninitiated have no idea of the cause.

In my opinion the basic LiquidCrystal library should concentrate on implementing all of the capabilities of the LCD controller and no more. If people want a library that more closely emulates a CRT (or LCD) terminal that is fine, but I think it should be done in a different library.

Let me start with where I started, I am working on a project involving and arduino and a display that I want to display a new quote once a day for a month, before needing to have new quotes loaded. I decided, because I wanted to run it off of battery power to try and use an e-paper display, I originally purchased a pervasive display 4.41 inch display along with an Arduino Uno. I was able to get the two talking over SPI, I was also able to send basic commands like refreshing the display, however, I soon realized that the display require 15K bytes of image data to be sent each time I want to load new image data. I decided to move up to and Arduino Due, which I was bale to get talking again, however, it stopped working, and I was have intermittent problems, to the point where I reconnected the Uno and even previous code I had written would not work as I expected. I can only assume I cooked something on the pervasive display timing controller? If anyone has a suggestion regarding this I would appreciate it.

I have now decided to try going with a regular LCD display, I am thinking about the 20X4 character display for simplicity"s sake. The next question would be how can someone who does not want to go into the code to change the quotes change them, I am assuming I would need to incorporate some sort of SD card interface.

SparkFun LCD page you liked to says the LCD you using is a 3V LCD display; HOWEVER, the datasheet shows it works from 2.7v to 5.5 - which means it really isn"t a 3v LCD.

We sell tons of lovely character LCDs for use with Arduino, they are extremely common and a fast way to have your project show status messages. This tutorial will show how you can easily connect a character LCD, either 16x2 or 20x4.

i"m sure all my connections are correct, the display works according to the program but it is very unclear even after adjusting the 10k pot..im not sure what the problem is please help me out..some extra info:

Yes, as I say, that error has been simply copied by one "tutorial" after another, and incorporated into the I²C backpacks since it "sort of" works so people think it is OK. But it makes contrast setting more difficult and wastes half a milliamp. That may not seem much to worry about except that the LCD itself uses less than a milliamp and this would be significant it operating from a battery. The backlight of course draws 20 mA.

Not really. You will note if you tried both ways, that the contrast control is much more flexible connected this way. Instead of working only over a very narrow range at one end, it works over a much wider range - at both ends.

This is the equivalent of turning the potentiometer all the way to the ground end. In general, it will work and is OK to test if you are having problems (as you are), but generally does not provide the clearest display.

And indeed, if that is the display with no code running, the fact that you get only half a line of blocks demonstrates that the display is definitely faulty.

So the verdict is a dead display. I was a bit puzzled with your original picture and thought you had a 2004 display but of course, it is a 1602. On a 2004, the uninitialised display is "blocks" on the first and third line.

Pardon us when we ask for your actual code, but we always want to check what is in your IDE, not what the tutorial said because - it isn"t always the same.

Not sure what you are trying to articulate there, but if you are talking about the resistor in series with pin 15, that is another story. It is unnecessary with AFAIK, all of the currently available 1602 and 2004 modules since "R8" on the back of the module is "101" or 100 Ohms.

Well, it always used to be, but on the one shown in #11, "R7" is now 330 Ohms so the external resistor is even less necessary. I can"t quite see what "R8" is doing here, but it appears to add another 220 Ohms also. An extra resistor will not hurt things, it will just dim the backlight slightly and save some current.

Dealing with these LCDs is really very interesting. Like so many other things they are really quite straightforward once you understand them but they seem really complex when you don"t. What makes them more challenging is that in some respects they require you to meticulously follow the data sheet and in other respects they are quite tolerant of deviations.

What really messes people up is that the various clones of the original Hitachi design seem to be tolerant of different deviations. So experimenter "A" comes up with some not exactly correct code that works with his LCD and passes on this "working" code. Experimenter "B", with a different brand LCD, tries it and when it doesn"t work for him he comes up with another version of not exactly correct code that works with his LCD and passes that code on....

Something completely different: I looked at your hd44780 library and the hd44780_I2Cexp.h file. The .h file contains a lot of implementation code instead of just declarations, violating proper programming practices. Wy did you organise it this way? What are the reasons you could not properly split declaration (interface) and definition (implementation)?

Specifically the hd44780_I2Cexp i/o class has support for two types of backpacks and when only one is being used there is close to 800 bytes to 1k of code that is not used taking up space.

I discovered it I2CScanner, a short sketch that lists all I2C devices connected at that moment. So, run it (with the LCD connected) and watch with Serial Monitor for the address of your LCD.

I just recently purchased an Arduino Uno 3 and I wanted to make an ultrasonic distance sensor that outputs the readings to a 16x2 LCD. I followed this guide:

http://www.mertarduino.com/using-ultrasonic-distance-sensor-hc-sr04-with-lcd-display-and-arduino/2018/11/22/ but it gave an error when I uploaded the code. The error was: a function definition is not allowed here before "{" token. I don"t know too much about Arduinos, so I need help.

Granted, the Arduino doesn’t have much use for text when used on it’s own. It has no display. But a display can be attached, or text can be send/received through the serial port and other ways of communication.

In the case of a string, the array keeps going, until your Arduino finds a NULL character. The NULL character terminates the string – or indicates the end of the string.

It’s character zero. But we do not (yet) have to worry about that – but it is something to keep in mind. Since strings are quite often used, the language “C” which we use for Arduino Programming, comes with a standard library of string related functions, which handle quite a lot already automatically.

Note that if the number is bigger than the number of characters we need, then this will work just fine. However, your Arduino might allocate the extra characters as well and waste memory space as we’re not using it. On the other hand, if you expect the string to change in the program and all those characters might be needed, then you’d already be prepared.

Not really. Remember how I said before that the variable (in our example “Name”) actually points to the memory location of the first element in the array? It’s a memory address, which is not the same as a string. Believe me, this is something you’ll run into quite often, and it’s one of the reason why I’m not a fan of the C-language (I’m more of a Pascal fan – and plenty of people will argue with me on that one).

Now sometimes we’d like to print for example double quotes, but just typing them into a string will not work – the string would break. The compiler will think you’re done after seeing the second double quotes and everyting remaining will become an unclear mess.

The code highlighting of the Arduino IDE text editor, will show you if a string “breaks” or not, by changing character colors in the string you just typed.

The first line shows us the wrong way of doing it. The keywords of importance are printed in orange en the string in a green-like color. But … our string has a chunk of black text in it. The word “guest” is black. It means that this is not part of the string, which is caused by the double quotes around the word “guest”.

Note that when you want the next character to be special as well, then you’d need to “escape” those as well. For example if we add multiple double quotes around the word “guest”: Serial.println("Hello \"\"guest\"\", welcome to Arduino");

Obviously, using ASCII is not the obvious way to do it when you’d like to assign text to a string. However, there are scenario’s where this can be very practical. I’ll illustrate this with a quick nonesense example, which quickly lists all the letters of the alphabet, where we can use a “for” loop to count from 65 (=A) to 90 (=Z).

“strlen()” (read as: String Length) takes one parameter, a string, and returns the number of characters in the string. It will however not count the NULL character at the end.

When we added ” has two nephews, called Bram and Max!” to that string/array, we royally exceed the pre-defined space, and your Arduino will try to print that anyway. Not being able to find the NULL character (we have overwritten it with a non-NULL character, a space-character, in this example), it will keep spitting out whatever is in memory until it finds a NULL character. Which might be right away, or never …

Another reason is that once an object has been defined, it actually kind-a behaves like a data type, which can use for variables. Say we have one “car” then we create a variable “MyCar” as the object (data type) “car”. But if we have a garage filled with cars, then we can re-use that same definition to create multiple variables (MyCar, YourCar, DadsCar, MomsCar), or even an array of cars (Cars[0], Cars[1], Cars[2],…).

With “Serial” we have already seen the methods (functions) “begin”, “print” and “println”. We call these methods to have the object do something , like start communication, or send a string to our Serial Monitor of our Arduino IDE.

As mentioned and shown before: the array of char variant of a string is a little cumbersome to work with. So the good people at Arduino created an object to make working with strings easier. Again a reminder: it’s the “String” with a capital “S”!!!

As we have seen with the old “string”, we can simply create a variable and assign it a value in one single line. Nothing new there, well except for the keyword “String” of course and the lack of square brackets.

Now let’s make that string longer, in the previous example, when using the array of char “string”, we noticed that we had to pay attention to the size of the array, so we wouldn’t go beyond it’s capacity. The “String” object however saves us that worry. It corrects automatically.

For two reasons. For one, the object will take up more memory, since it has all these fancy properties and methods. Another reason is that the String object, actually uses the “string” array of characters as well.

Now the “String” object, has a lot of methods (functions) we can work with, which can make our life a lot easier when working with strings, and this is where we will really see the power of objects.

We create the String object “Name” and assign it the value “Hans” (lines 7 and 8), which we can print with “Serial” as we have seen before. Now in line 12, we retrieve the length of our string – which is just the number of characters in the string, and not including the NULL terminating character. This is done with the “length()” method of the “String” object: Name.length() . This method will return a number, an integer, which we send right away to “Serial.print”.

The “String” object however is even more powerful and can right away convert a number (int in this example) to a string, and replace or attach it to an existing string – see line 34 – which is something we cannot do with the previous “string” array of characters.

The reason why this fails, is because we are comparing a string with the memory location “pointer” of an array. Which will not be the same obviuosly. We actually need to use a special function for this: “strcmp()”  (read that as “string compare”)

When comparing the two strings, it will actually compare the ASCII values. So when it returns a number greater than zero, it actually means that it ran into a character which has a greater ASCII value compared to the other character, in the same position in the other string, and this can be confusing, because we humans would expect “Hans” to be greater than “Hi” – but its not. This is in part also because we humans see the longer string “Hans” as the larger one of the two.

What is the purpose of declaring LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); if we are using pins A4 and A5? I know that 0x27 is the ic address but what is the rest for?

I am getting a error while i m going to add zip file of lcd library error id this zip file does not contains a valid library please help me to resolve this issue as soon as possible.....

Hey guys. My LCD works fine using the above instructions (when replacing the existing LCD library in the Arduino directory) but I can"t get the backlight to ever switch off. Suggestions?

This project is created byDIYODE Magazineand is originally published onDIYODE Magazinewhere they also did an informative review on Seeed Studio"s Wio Terminal. I personally love this project and decided to share it here on Hackster. Please do note the following documentation is written byDIYODE Magazine Team.

For our first project, we’re using both the inbuilt LCD screen and WiFi module to get text data of famous quotes. Since we’re all nerds at DIYODE, we’ve of course chosen to choose famous programming quotes. The center button of the Wio Terminal will be used to load a new quote and display it on the screen.

WiFi is involved here because we’re using a simple Web API to gather data and display it live. Since it’s connecting to WiFi, we could connect it with virtually any other web interface and make it work.

After installing the required WiFi libraries, we can open a new Arduino sketch and pop in the following initialization code. Unless your WiFi network so happens to be named “YOUR_WIFI_NAME” and has the password “YOUR_WIFI_PASSWORD”, you’ll want to change them to your home network details!

There isn’t a ton of libraries we need to import here. We’re using the Arduino JSON, rpcWiFi and HTTPClient libraries to handle the internet connection and data, and the TFT_eSPI library to handle the screen on the Wio Terminal.

The ‘wasPressed’ variable will be used during the main loop to ensure we only display one new quote when the button is pressed, and not to continue looking for quotes when the button is held. This is typically referred to as state detection, and we’ll talk about this shortly.void setup() {

To make the WiFi and networking features work, you’ll need to reflash the WiFi firmware on the Wio Terminal. The official Seeed guide can be found here:https://wiki.seeedstudio.com/Wio-Terminal-Wi-Fi/

It’s not as difficult as it sounds, and it only took us 10 minutes. If you’re wondering why the WiFi isn’t working on your Wio Terminal, there’s a good chance that this will fix the problem.

Also notice that there is a considerable number of calls to the Serial command, which essentially allows us to debug and inspect the functionality of the Wio Terminal by opening the Serial Monitor (Shortcut – Ctrl+Shift+M).void loop() {

This is where the real heavy lifting happens! In our loop function, we’re using that ‘wasPressed’ variable mentioned before to respond only when the button is pressed, and not continuously held.

Text wrapping is the process of bringing text fields down to the next line on the screen if it’s too long – which is often the case with quotes. The LCD library does have this function built-in, but it wasn’t cooperating for us, so we wrote it ourselves!

Essentially, we’re taking ‘chunks’ out of the text with the substring function and writing each to one line of the Wio Terminal’s LCD screen. The ‘len’ variable describes the number of characters on each line. If the function is confusing, just change some values and observe the effects!

…and boom! It’s all working. Inspiring programming quotes at the press of a button. Obviously, this isn’t the most practical program ever – but it’s a good starting program to experiment with the Wio Terminal and to demonstrate its capabilities with precisely zero external wiring required.

This means that your string needs to have space for one more character than the text you want it to contain. That is why Str2 and Str5 need to be eight characters, even though "arduino" is only seven - the last position is automatically filled with a null character. Str4 will be automatically sized to eight characters, one for the extra null. In Str3, we"ve explicitly included the null character (written "\0") ourselves.

Note that it"s possible to have a string without a final null character (e.g. if you had specified the length of Str2 as seven instead of eight). This will break most functions that use strings, so you shouldn"t do it intentionally. If you notice something behaving strangely (operating on characters not in the string), however, this could be the problem.

It is often convenient, when working with large amounts of text, such as a project with an LCD display, to setup an array of strings. Because strings themselves are arrays, this is in actually an example of a two-dimensional array.