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12 votes
Accepted

16x2 LCD showing blocks under text

The row of white blocks is what you get before the screen's initialized. It's normal. The shadow behind the characters is because you have the contrast turned up too high. Adjust it down a little.
  • 103k
11 votes

Request for help condensing code and saving memory

You have a huge switch...case here to decide the name of the file that should be played. This costs a lot of code space, but also data space, because every single literal string in this portion of ...
  • 37.3k
8 votes

Why is my LCD 16*2 is not displaying any characters, although all the wiring is correct?

Recently I also faced similar problem, with connection as: 1=GND, 2=+5v, 4=11, 6=12, 11=5, 12=4, 12=3, 14=2, 15=backlight positive, 16=backlight negative Solution: I just connected VEE (pin 3) of ...
  • 81
7 votes
Accepted

Why is my LCD 16*2 is not displaying any characters, although all the wiring is correct?

Check out this tutorial on Adafruit. It will walk you through setting it up. In the tutorial they change the pins, which I believe is the issue here. Here is a snippet. And change your pins: ...
  • 1,128
7 votes
Accepted

2.4" TFT LCD Shield isn't working on Arduino Mega

I just happened to buy the same LCD Shields a few days ago, looking for a library to use it with a MEGA 2560 board I found https://github.com/Smoke-And-Wires/TFT-Shield-Example-Code which supports ...
7 votes
Accepted

Hooking up LCD screens reclaimed from old camcorders to Arduino

This is likely a type of TTL LCD interface. But it is nearly impossible to describe more as there are so many variations both in hardware and in timing. Likely a steady stream of Red Green & Blue ...
  • 6,636
7 votes
Accepted

Implement two processes at the same time

Think of an Arduino as a circus clown spinning plates. It has to spend very little time on any one plate, and then it can keep a lot of plates spinning, moving quickly from one to the next. That's how ...
  • 5,519
6 votes
Accepted

Arduino LED backlight - should PWM be used with transistor or capacitor?

You don't need the MOSFET, you don't need the capacitor, you do need the resistor. The pins on your Arduino can deliver up to 20mA comfortably, so in this case there is no need for the MOSFET. ...
  • 464
6 votes
Accepted

I2C LCD displaying weird characters

If you look up the ASCII codes for what you sent vs what was displayed, and also look at "Table 4 Correspondence between Character Codes and Character Patterns (ROM Code: A00)" in an HD44780U spec ...
6 votes
Accepted

Print string and integer LCD

The lcd.print() method takes a string or a number as an argument, but not both at once. Using the + operator for concatenation is not native to C strings. C strings are basically stored as pointers to ...
6 votes
Accepted

Does a graphical driver chip exist for this project?

I have no idea if there is a chip or not, but I doubt it. But then, why do you need one? You already know how to communicate with the screen, so why not off-load those functions on to another ...
  • 103k
6 votes
Accepted

Why do I get "invalid operands of types 'const char*'" error?

Your first code took a String object, then added other strings (note lowercase) to it - which are characters enclosed in quotes. It is legal to add strings to String objects. Your new code doesn't ...
  • 1,815
6 votes

Print output on 16x2 LCD and Serial Monitor

If you are using clasical UNO, then pins 0 and 1 are Serial. Declaring lcd(1,... make LCD use the pin 1 too, so Serial is confused and garbled. Use other pins for lcd and adjuct the wires acordingly.
  • 1,300
6 votes
Accepted

Simple LCD countdown timer

instead of 9, it printed 90 No, it didn't: it printed “9”. However, it did not erase the previous value before printing “9”. Before printing the 9, the LCD had: ┌────────────────┐ │time left │ │...
  • 37.3k
6 votes
Accepted

Read serial with header and end marker

The short answer to your question is “yes, there is a way”. Multiple ways actually. You could write a blocking function, which follows more or less the logic of the example you show, blocking while ...
  • 37.3k
6 votes
Accepted

lcd.createChar() only allows for 8 custom characters

These displays only allow up to 8 custom defined characters. The hardware just only has the character RAM for at most 8 characters. They will be mapped to char codes 0 to 7 and 8 to 15. The character ...
  • 1,074
5 votes

Instead of 1 and 0, make display say On or Off

Put the strings to display in an array, and output them instead. char const * const stateDisplay[] = {"Off", "On"}; ... lcd.print(stateDisplay[state]);
5 votes
Accepted

Arduino DC motor causes disturbance. What can cause it?

Thanks for the help everyone. I fixed it by using Capacitors. They suppress the noise that the dc motor produces. I found my information here
5 votes

Nokia 5110 Screen Pixel by Pixel

The 5110 Nokia LCD display is based on PCD8544. It is not possible to read the device display memory. The controller has only serial data input. Typically a graphical device driver for that display ...
  • 7,861
5 votes

How to show the º character in a LCD?

Some displays have different characters above 128. It is best to make your own character. That is what @dannyf ment with "CGRAM". The custom characters are stored in CGRAM. There is no need to read ...
  • 3,107
5 votes
Accepted

Flip text in LCD screen

It's not possible. The text is a simple ASCII character set that is encoded in ROM. It can't (other than a few user-defined characters) be changed. And being simple ASCII it doesn't support any ...
  • 103k
5 votes
Accepted

I2C sensors not working when I connect to LCD 20X04

Welcome to Stack Exchange! I can spot a few problems with the circuit. As @hcheung said, the I2C pull-up resistors should only be wired between SDA>3.3V and SCL>3.3V (in parallel), not in series ...
4 votes

Unusual LCD behaviour

Insufficient decoupling. Put a 100nF cap on the supply lines at the LCD and a 100uF cap on the supply lines at the servo.
4 votes

Program Arduino Uno as a digital clock

Im with @arvid-jense on this one, if you are working on a serious Digital Clock, then you should get the Real Time Clock. Now if you are learning Arduino and want to play with your LCD Minidisplay ...
  • 143
4 votes
Accepted

How do I use two I2C LCDs with 4 pins?

With the I2C backpack there are three pairs of landings, A0, A1, A2, which determine the 3 LSB of the device's address, using inverted binary. Left alone, they generate part of the F or 7 part of ...
  • 1,141
4 votes
Accepted

Sending a value from one arduino to another

You could have the LCD Arduino be an I2C master and all the weighing Arduinos be slaves. There's an example of master/slave communication and wiring here: https://www.arduino.cc/en/Tutorial/...
4 votes

What could make an LCD stop working permanently after being connected for 5 seconds to Arduino?

It's unlikely that you have killed the unit as this is pretty hard to do from the data interface and your picture is typical for an LCD that has not gone through the initialization sequence. A dead ...
4 votes
Accepted

LCD 16*02 I2C shield only shows first character printed

That's definitely a bug appeared in 1.6.6. For reference, see https://blog.arduino.cc/2015/11/03/arduino-ide-1-6-6-released-and-available-for-download/#comment-278766 https://forum.arduino.cc/index....
  • 193
4 votes
Accepted

Library LiquidCrystal_I2C don't work in other class (Composition)

Most likely cause You are hitting an insidious problem that even experienced C++ programmers frequently miss: order of initialization of global variables. In your case, Display lcd is initialized (i....
  • 746

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