mathertel / liquidcrystal_pcf8574

A library for driving LiquidCrystal displays (LCD) by using the I2C bus and an PCF8574 I2C adapter.

Open Source Projects by Matthias Hertel (mathertel)

In this GitHub User place you can find current public projects. See more on https://mathertel.github.io and https://www.mathertel.de.

Library Status Overview

Arduino Libraries

OneButton:

DMXSerial:

DMXSerial2:

HomeDing:

RotaryEncoder:

Radio:

LiquidCrystal_PCF8574:

rfcodes:

liquidcrystal_pcf8574's Issues

Effects not working with text longer that 16 char

/*
This code is not working, the line with effects overlaps at the begining of the line replicating one char
If I change the line fx.applyEffect(text, 11, 18, effect::invert); to fx.applyEffect(text, 11, 15, effect::invert); // bold "Hello"
it does not apply the desired effect but do not overlap

Did I make any mistake ?
*/

#include <Arduino.h>

#include <Wire.h>
#include <LiquidCrystal_PCF8574.h> // should work with any LCD library
LiquidCrystal_PCF8574 lcd(0x27);

void make_char(char c, uint8_t* image){ //need this function to pass to LcdEffects
lcd.createChar(c, image); // so it knows how to make custom characters
}

#include <LcdEffects.h> // the core library
#include <Effects.h> // a collection of common effects
LcdEffects<> fx(make_char); // initialize the LcdEffects library

void setup() {
lcd.begin(20, 4); //change to match the size of your LCD
lcd.setBacklight(255);
}
void loop() {
char text[] = "12345678901234567890"; // puts the text in an array so we can work with it
lcd.setCursor(0,0);
lcd.print(text); //print the text to the first line without any effects (for comparison)

fx.applyEffect(text, 0, 5, effect::invert);
fx.applyEffect(text, 7, 10, effect::bold);
fx.applyEffect(text, 11, 18, effect::invert);

lcd.setCursor(0,1); //now print the text to the second line
lcd.print(text);

delay(1000);
}

Sample Code For custom characters

Hi,
Put Displaying custom character on LCD sample code.

Individual files can't be changed from LGPL to dual license with BSD

Since you don't fully own the copyrights to the original work there are licensing restrictions on the files and the combined work.

LGPL does allow the linking of LGPL files with more files that use lax licenses such as BSD; however, there are some incompatibilities so you can't use a dual license of LGPL and BSD on a single file.

i.e. LGPL is not as permissive as BSD and you can't convert LGPL licensed s/w to BSD even if you modify it into a derivative work.
Read section 2 of the LGPL license specifically 2c
i.e. the code started as LGPL 2.1+ , any modifications and updates to that code must be licensed LGPL 2.1+

Also, when you link BSD and LGPL licensed works together, the combined work inherits the requirements of LGPL so the more relaxed licensing of BSD is lost.

i.e. if you have a work that contains separate modules some BSD and some LGPL any work that uses them both would be subject to LGPL.

This library started with LGPL 2.1+ code so it isn't possible to modify the code to make it BSD.

Licensing terms

If the code is a derivative of the Arduino LiquidCrystal code (as indicated by the comments in the code) any license used for this project must be compatible with the LiquidCystal license which is LGPL 2.1+
LGPL 2.1+ licensed code can not be changed to a more permissive license such as BSD or MIT.
It would have to remain LGPL 2.1+

Backlight brightness does not work as expected

Seems that void LiquidCrystal_PCF8574::setBacklight(uint8_t brightness) does not work as expected and at least on my display it is merely on or off. Passing 0 toggless the backlight off and any positive value toggless it fully on.

Might be that it works on some other boards though.

Change the bit allocations?

Hi.

No default constructor for common PCF8574 LCD address 0x27

Hi
Many of the PCF8574 LCDs (all of mine) use address 0x27 and this is the example value in the .h file.
Suggestion: Provide a default constructor value to allow easy compatibility/min code change when changing LCD type in an existing project.

Best regards
Rob

LCD Write Odd Wrapping

Hi. Odd behaviour when writing long strings to a 20 × 4 display.

Starting with the cursor at 0, 0. When a string exceeds 20 characters, the balance of the string wraps to the third line of the display. If the string exceeds 40 characters, the balance wraps to the second line. If the string exceeds 60 characters, it wraps to the fourth line.

So the writing wrapping order is:
Line 1
Line 3
Line 2
Line 4.

For example, using a "serial echo" sketch, send the string:

1-abcdefghijklmnopqX2-abcdefghijklmnopqX3-abcdefghijklmnopqX4-abcdefghijklmnopqX

It shows up on the display as:

1-abcdefghijklmnopqX
3-abcdefghijklmnopqX
2-abcdefghijklmnopqX
4-abcdefghijklmnopqX

Demo sketch attached
LCD_SerialDisplay2.ino.zip
.

optimising _sendNibble to write faster (about 3 time less I2C send for the same job)

Hello
I propose a small modification to the so I2C is open and close 4 time less and so you can write faster to LCD device

I am new to github and arduino (but i have 20 years of ASM programing and hardware on lot of processor but classical way :) )
I give you the modifications but may be I should make a clone ? (this is not clear for me)

LiquidCrystal_PCF8574.zip

LiquidCrystal_PCF8574::print() doesn't handle '\n' character

For example, for string "hello\nworld" on display 16x2 word "hello" should be on first line and "world" on second line.

Non asci characters

Thanks for a great library! It was the only one which worked with my display.
I want to display characters with umlauts which are not in the asci character set. Do you know how to do that?
Example:
lcd.print("ä ö");

LCD 16x4 behaves strange.

How to go about with a 16x4 display ? pos (0,2) and (0,3) starts on position (4,2) and (4,3).

Here is the code:
lcd.clear(); lcd.setCursor(0, 0); lcd.print("*** first line."); lcd.setCursor(0, 1); lcd.print("*** second line."); lcd.setCursor(0, 2); lcd.print("*** third line."); lcd.setCursor(0, 3); lcd.print("*** fourth line.");

LCD show ramdom caracteres after a while

hello very good library. i am new to arduino but

I would like to know if there is any reason why the LCD screen shows random characters after a while.

eg bad settings ?, noise ?, is it a common feature on LCD? does the library have any functions that allow me to take control of the lcd again?

Thank you.

Compactible With PCA8574?

I have tested with Arduino Nano Every with I2CLCD 16x2 and I2CLCD 20x4 with PCA8574 I2C expander. Both failed.

no matching function for call to 'LiquidCrystal_PCF8574::createChar(int, byte [8])'

I defined the character as a byte
byte cM[8] = {B01100, B10000, B10000, B01100, B10001, B01010, B00100, B00100};

initialise in setup with
lcd.createChar(0, cM);

When I compile I get this error

no matching function for call to 'LiquidCrystal_PCF8574::createChar(int, byte [8])'