Arduino with i2c lcd

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hi all,

I have connected my Arduino with my 16x2 lcd via 12c module. after loading code it shows only bright green screen with two blank lines.
on the other hand when i see the lcd from side, it shows some absurd characters moving fast from left to right.
what could be the problem here? is lcd faulty?

lcd used

Silicon Technolabs Lcd 16X2 Yellow Backlight Alphanumeric Display for 8051,Avr,Arduino,Raspberry Pi,Pic,Arm All Microcontroller (Green) : Amazon.in: Computers & Accessories

Silicon Technolabs Lcd 16X2 Yellow Backlight Alphanumeric Display for 8051,Avr,Arduino,Raspberry Pi,Pic,Arm All Microcontroller (Green) : Amazon.in: Computers & Accessories
www.amazon.in

i2c interface to connect lcd with Arduino uno

Buy I2C Module LCD Serial Display Adapter Online in India

Module: I2C/IIC Module Compatible LCD: 16x2 and 20x4 Headers: soldered Buy I2C module for LCD display online at low price in India
www.roboelements.com


schematic is attached herewith.


Code: 
// Include the libraries:
// LiquidCrystal_I2C.h: [URL]https://github.com/johnrickman/LiquidCrystal_I2C[/URL]
#include <Wire.h> // Library for I2C communication
#include <LiquidCrystal_I2C.h> // Library for LCD

// Wiring: SDA pin is connected to A4 and SCL pin to A5.
// Connect to LCD via I2C, default address 0x27 (A0-A2 not jumpered)
LiquidCrystal_I2C lcd = LiquidCrystal_I2C(0x27, 16, 2);

void setup() {
  // Initiate the LCD:
  lcd.init();
  lcd.backlight();
}

void loop() {
  // Print 'Hello World!' on the first line of the LCD:
  lcd.setCursor(0, 0); // Set the cursor on the first column and first row.
  lcd.print("Hello World!"); // Print the string "Hello World!"
}
 

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Your loop is running far too fast. Add a delay, I suggest 0.5S, after the 'lcd.print("Hello World!");' line and you will then see what is happening.

I use the same LCD and I2C expander here very successfully.

Brian.
 

betwixt said:
Your loop is running far too fast. Add a delay, I suggest 0.5S, after the 'lcd.print("Hello World!");' line and you will then see what is happening.

I use the same LCD and I2C expander here very successfully.

Brian.
Click to expand...

now i see junk char moving from left to write slowly. can there be pin soldering issue also ... i solder i2c adapter to lcd my self ...it did not come manufactured.
 

I From the schematic, seems like you missed the pull-up resistors on the I2C bus.
 

andre_teprom said:
I From the schematic, seems like you missed the pull-up resistors on the I2C bus.
Click to expand...
i think pull-up register would have been handled in the i2c break board i am using. otherwise it would have been shown in the schematics which i am referring to. please correct if i am wrong.

 

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I just checked the same PCB here and it does appear to have 4K7 resistors between SCL & SDA to the VCC pin. No very clever design if used in a multi-board environment but it does make this application simpler.

Brian.
 

betwixt said:
I just checked the same PCB here and it does appear to have 4K7 resistors between SCL & SDA to the VCC pin. No very clever design if used in a multi-board environment but it does make this application simpler.

Brian.
Click to expand...

i readjusted the pins between I2c and lcd and later observed that char are seen only when you tilt the screen then i adjusted the brightness and now every thing seems to be ok.
 

One problem with the approach is update rate of LCD as you see, the delay helps,
but you can still get artifacts when writing display repeatedly with same info.

One approach, very effective, is to create a buffer in ram, same form factor as display,
in this case array 2 x 16. When you go to write you compare, character for character,
the new info versus the array.l If different you update array, only characters that change,
followed by display update, onlky characters that change.

If no differences NOP. That will cut out a lot of display artifacts.


Regards, Dana.
 

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