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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.
Majenko's user avatar
  • 105k
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 ...
Edgar Bonet's user avatar
  • 43.3k
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 ...
Suraj's user avatar
  • 81
7 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 ...
John Burger's user avatar
  • 1,875
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 ...
st2000's user avatar
  • 7,338
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 ...
Duncan C's user avatar
  • 5,702
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.
gilhad's user avatar
  • 1,420
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 │ │...
Edgar Bonet's user avatar
  • 43.3k
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 ...
Edgar Bonet's user avatar
  • 43.3k
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 ...
PMF's user avatar
  • 1,296
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 ...
Jot's user avatar
  • 3,246
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 ...
Majenko's user avatar
  • 105k
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 ...
Liftyee's user avatar
  • 126
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 ...
SDsolar's user avatar
  • 1,165
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....
JayEye's user avatar
  • 756
4 votes
Accepted

How to sleep a whole circuit?

The first and most smart solution is to use a switch between the batteries and everything else. This way, you slide the switch in the off position and the whole circuit is completely detached from the ...
frarugi87's user avatar
  • 2,721
4 votes
Accepted

ATTiny85 I2C LCD

After hours of Googling, I found a blog post by Dimitris Platis where he describes using an ATTiny85 with I2C LCD. I emailed the guy and he replied with a link to his LCD I2C ATTiny library on GitHub. ...
Thijs's user avatar
  • 432
4 votes
Accepted

How do I change the I2C address on the LCD backpack?

As mentioned in the page you linked, jumper together one of the address jumpers. For example, above A0 are two pads. Solder a wire across them (vertically - between the two pads above A0). I am ...
Nick Gammon's user avatar
  • 38.3k
4 votes

How should I initialize a RepRap Discount 12864 on u8glib?

I solved the problem myself. It turns out to be a problem of wrong pinouts. My PCB of the project was originally designed for the LCD2004 counterpart, and I thought it was a drop-in replacement for ...
user2513881's user avatar
4 votes

Hacking old car dvd monitors with arduino

I realize this is an ancient question, but just in case someone else has one of these things, I'll share what I know. I have one of these Sharp LCDs that I typically use as a monitor for a Commodore ...
BYTESHiFT's user avatar
4 votes

Why the command noDisplay() clear all LCD screen?

I tried out your code. It's working absolutely fine. Whenever lcd.noDisplay() executes then LCD not displaying hello, word!... And whenever lcd.display() executes then LCD displaying hello, word!... ...
Hasan's user avatar
  • 1,476
4 votes

Arduino board is turning off when I connect to +5V

Try out this connection. It will helpful.
Hasan's user avatar
  • 1,476
4 votes
Accepted

Compatibility between shields

Its not just a question of the stackability of the shields and the clash of pins you also need to consider what the shields do. Stacking the GSM shield under the LCD is going to restrict is tx/rx ...
Code Gorilla's user avatar
  • 5,637
4 votes

Adding an LCD to Uno but not enough pins left

You are using 8 GPIO pins for your existing modules. That leaves 12 left for an LCD (assuming you aren't using the serial port). An LCD can work from as few as 6 pins (4 data, E and RS) - WR can be ...
Majenko's user avatar
  • 105k
4 votes
Accepted

Can I generate 5 sec delay within an interrupt program?

You don't need interrupts for any of that. Your main loop just needs to test the switch, eg. void loop () { if (digitalRead (button) == HIGH) // assuming LOW means pressed return; // ...
Nick Gammon's user avatar
  • 38.3k
4 votes
Accepted

Resistors on LCD - does a small difference matter?

No, it doesn't matter. That resistor is just for the backlight LEDs. The larger the resistor the dimmer the backlight will be. As @VE7JRO suggests, you can always put two 330Ω resistors in parallel, ...
Majenko's user avatar
  • 105k
4 votes
Accepted

My brand new LCD screen doesn't display anything, even though there is no code errors?

Turns out that the diagram was wrong. Needed to move the potentiometer 1 pin to the right, now it works!
Ben Stafford's user avatar
4 votes

How to make an arduino button to forget his past purpose?

What you likely need is a state machine. The behavior of the actions depends on the state the program is currently in. In your case, the state machine might look like this: What does it mean? black ...
Thomas Weller's user avatar
4 votes

How to convert my Arduino setup to a PIC setup?

The PIC32 has full (or nearly full) support for the Arduino API through the chipKIT project. If you want to use one of the smaller PIC chips (PIC16 / PIC18 etc) then you're out of luck. There just ...
Majenko's user avatar
  • 105k

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