LCD displaying white lines [S0lV3D]

jasonbebrilliant · October 18, 2024, 2:39pm

I use I2C 4 PIN 16 x 2 LCD.

I compiled the following code and it was compiled sucessfully

// C++ code
//

#include <Adafruit_LiquidCrystal.h>

int trigger = 7;

int echo = 6;
Adafruit_LiquidCrystal lcd_1(0);


void setup()
{
  Serial.begin(9600);
  pinMode(7, OUTPUT);
  digitalWrite(7, LOW);
  pinMode(echo, INPUT);
  lcd_1.begin(16, 2);
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);
  pinMode(2, INPUT);
  
}

void loop()
{
  float cm = 0;
  double time = 0;


  digitalWrite(7, HIGH);
  delayMicroseconds(2);
  digitalWrite(7,LOW);
  time = pulseIn(echo, HIGH);
  cm = time*29/2*0.0473/100*2.511111;
  Serial.println(cm);
  
  lcd_1.setCursor(0, 0);
  lcd_1.setBacklight(1);
  lcd_1.print("cm: ");
  lcd_1.setCursor(0, 1);
  lcd_1.print(cm);
  lcd_1.print("cm +-0.1cm");
  delayMicroseconds(30);
}

and for circuit, I used following circuit

but it doesnt work any ideas?

jasonbebrilliant · October 18, 2024, 2:40pm

it worked on simulation on tinkercad but it didnt work on real arduino uno

LarryD · October 18, 2024, 2:49pm

Remove the GND from the switch, in fact, keep the LCD power always connected.
What is the I2C address ?

ec2021 · October 18, 2024, 2:52pm

Hi @jasonbebrilliant ,

install the library "LiquidCrystal I2C" and try this

#include <LiquidCrystal_I2C.h>

const byte I2C_ADDR    =   0x27;
const byte LCD_COLUMNS = 16;
const byte LCD_LINES   = 2;

LiquidCrystal_I2C lcd_1(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

and outcomment the existing lines as follows

//#include <Adafruit_LiquidCrystal.h>
//Adafruit_LiquidCrystal lcd_1(0);

Good luck!
ec2021

P.S.: I looked into the Adafruit_Liquidcrystal Library and found this

  /*!
   * @brief LiquidCrystal constructor for connection over i2c
   * @param i2cAddr Address of the display. Can use either actual I2C address
   * (0x20, 0x21, etc.) or offset from 0x20 base address (0, 1, etc.).
   * @param wire Optional pointer to Wire instance to use. Defaults to Wire.
   */
  Adafruit_LiquidCrystal(uint8_t i2cAddr, TwoWire *wire = &Wire);

So with the right call the lib you are using should support I2C as well.

It might be sufficient to try

Adafruit_LiquidCrystal lcd_1(0x27);

P.P.S.: Neither (0) nor (0x27) does work in the Wokwi Online simulation while the lib LiquidCrystal_I2C works without problems ...

@LarryD : Do you have experience with the Adafruit lib and I2C?

jasonbebrilliant · October 18, 2024, 2:59pm

ok so i found that the address is 0x27 and changed

Adafruit_LiquidCrystal lcd_1(0);

to


Adafruit_LiquidCrystal lcd_1(0x27);

now it starts to display this:

is this a good sign or bad sign?

*also i removed the switch

jasonbebrilliant · October 18, 2024, 3:00pm

oh thanks!

ill try

#include <LiquidCrystal_I2C.h>

const byte I2C_ADDR    =   0x27;
const byte LCD_COLUMNS = 16;
const byte LCD_LINES   = 2;

LiquidCrystal_I2C lcd_1(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

jasonbebrilliant · October 18, 2024, 3:03pm

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jasonbebrilliant · October 18, 2024, 3:04pm

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ec2021 · October 18, 2024, 3:07pm

That's too much ...

Actually the example for i2c displays on github

https://github.com/adafruit/Adafruit_LiquidCrystal/blob/master/examples/HelloWorld_i2c/HelloWorld_i2c.ino

uses the address 0

// Connect via i2c, default address #0 (A0-A2 not jumpered)
Adafruit_LiquidCrystal lcd(0);

so you used a correct call but it seems not to work in simulation and reality (where reality is more relevant).

Have fun!
ec2021

LarryD · October 18, 2024, 3:35pm

Yes

ec2021 · October 18, 2024, 3:51pm

I understand that it should work for standard 0x27 address if the call is

Adafruit_LiquidCrystal lcd(7);
or
Adafruit_LiquidCrystal lcd(0x27);

Using zero would address 0x20 as I looked up in the library:

Adafruit_LiquidCrystal::Adafruit_LiquidCrystal(uint8_t i2caddr, TwoWire *wire) {
  _i2cAddr = i2caddr <= 0x07 ? 0x20 | i2caddr : i2caddr;

Both options obviously do not work on Wokwi for (at least for me ) unknown reasons.

I made a test sketch using both libs depending on a define.

https://wokwi.com/projects/412097242415977473

Maybe a bug in the Wokwi simulation ... ?!?

P.S.: Just found this on github after searching for "Wokwi Adafruit_LiquidCrystal":

It's from 2021 and found in a thread regarding the ATtiny85

https://github.com/wokwi/wokwi-features/issues/152

but probably still valid ...

Think that's enough investigation for today

xfpd · October 18, 2024, 6:52pm

Please, refrain from starting multiple topics with the same subject.

jasonbebrilliant · October 18, 2024, 3:40pm

When I turn the power while the slideswitch is on, it works but if i turn the slideswitch off and on again, it displays some white lines

the video link

my code

// C++ code
//

// #include <Adafruit_LiquidCrystal.h>
#include <Arduino.h>
#include <LiquidCrystal_I2C.h>
// #include <string>

const byte I2C_ADDR    =   0x27;
const byte LCD_COLUMNS = 16;
const byte LCD_LINES   = 2;

LiquidCrystal_I2C lcd_1(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

int trigger = 7;

int echo = 6;
// Adafruit_LiquidCrystal lcd_1(0x27);


void setup()
{
  Serial.begin(9600);
  pinMode(7, OUTPUT);
  digitalWrite(7, LOW);
  pinMode(echo, INPUT);
  lcd_1.begin(16, 2);
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);
  pinMode(2, INPUT);
  pinMode(8,INPUT);
  
}

void loop()
{
  float cm = 0;
  double time = 0;


  digitalWrite(7, HIGH);
  delayMicroseconds(2);
  digitalWrite(7,LOW);
  time = pulseIn(echo, HIGH);
  cm = time*29/2*0.0473/100*2.511111;
  Serial.println(cm);
  
  lcd_1.setCursor(0, 0);
  lcd_1.setBacklight(1);
  lcd_1.print("cm: ");
  lcd_1.setCursor(0, 1);
  lcd_1.print(cm);
  lcd_1.print("cm +-0.1cm");
  delayMicroseconds(1000);
}

my circuit

I know it worked perfectly without switches, but I want switches for for some reason

is there any ways too do this???

LarryD · October 18, 2024, 3:48pm

LCD is configured at Arduino power up time.
Turning the LCD off with a switch, looses this LCD configuration.
When you turn the LCD back ON with the switch, there is no LCD configuration in the display.
A switch can be monitored by the Arduino and the LCD blanked if need be.

Paul_KD7HB · October 18, 2024, 3:49pm

To do what, exactly???? What are you trying to accomplish by turning the power off to the display and then never initializing the display in your code?

jasonbebrilliant · October 18, 2024, 3:59pm

I tried to turn off the display and turn it on again

jasonbebrilliant · October 18, 2024, 4:00pm

thanks

xfpd · October 18, 2024, 6:52pm

Please, refrain from creating multiple topics with the same subject.

Coding_Badly · October 20, 2024, 4:19am

Threads merged.

Paul_KD7HB · October 20, 2024, 5:13am

So, just testing and the result is what you can expect if you do not follow through by initializing the controller inside the LCD display.

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LCD displaying white lines [S0lV3D]

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