Screen just flickers using LiquidTWi lib

Other Hardware Displays
1

HI all.

I have an Amazon i2C screen, I am using the liquidTWI library, unfortunately it just flickers when I try to use the example sketch and never displays anything.

I used a test sketch and serial monitor to confirm the address of the I2c and it is correct.

When I use the wrong address the screen stays static but when i upload the test sketch "hello world" it flickers.

Any ideas?

2

post a link to the so called "Amazon i2C screen" and post the so called code for the "test sketch"... (please use code tags).

Also post a hand drawn diagram of the various connections and describe the power supply.

3

The screen appears to be recognised as connected correctly as the code for getting the i2c address via serial monitor works great.

The connections are as follows

Clock from screen -> A5
Dat from screen -> A4
Vcc-> +5v ( also tried external +5v injection and also stand alone external +5v power with no change)
GND -> common ground

Display:

/*
 Demonstration sketch for Adafruit i2c/SPI LCD backpack
 using MCP23008 I2C expander
 ( http://www.ladyada.net/products/i2cspilcdbackpack/index.html )

 This sketch prints "Hello World!" to the LCD
 and shows the time.
 
  The circuit:
 * 5V to Arduino 5V pin
 * GND to Arduino GND pin
 * CLK to Analog #5
 * DAT to Analog #4
*/

// include the library code:
#include <Wire.h>
#include <LiquidTWI.h>


// Connect via i2c, default address #0 (A0-A2 not jumpered)
LiquidTWI lcd(0x27);

void setup() {
  // set up the LCD's number of rows and columns: 
  lcd.begin(20,4);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(1, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);

  lcd.setBacklight(HIGH);
  delay(500);
  lcd.setBacklight(LOW);
  delay(500);
}
4

Im not sure how to upload the video here.

I hope I explain well but if I purposly use the wrong I2C address, the screen just stays solid blank, if I use the correct I2C address then it flickers like mad.

5

Thanks

Which arduino are you using?

What happens if you leave the loop empty?

Have you tried a different library? I would highly recommend hd44780 - Arduino Reference

6

This works with my LCD.

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Set for 1 display with 4 rows of 20 columns
LiquidCrystal_I2C lcd1(0x27,20,4);

void setup() {

  lcd1.init();
  lcd1.backlight();

  lcd1.clear();
  lcd1.setCursor(0,0);
  lcd1.print("LCD 1");
}

void loop() {
}
7

Thank you, sorted now seems it was a bad library :slight_smile:
New library and it works

8

...and you can use multiple displays with this library.

9

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