Qapass 1602A Help!

Other Hardware Displays
1

I'm using a Qapass 1602A LCD screen for a arduino project to display something. When wiring up the screen the text in the code won't show and the backlight is the only visible thing showing to know if it's working, thank you!

Code:

#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // Turn off the blinking cursor:
  lcd.noBlink();
  delay(3000);
  // Turn on the blinking cursor:
  lcd.blink();
  delay(3000);
}

My wiring:

LCD RS pin to digital pin 12
LCD Enable pin to digital pin 11
LCD D4 pin to digital pin 5
LCD D5 pin to digital pin 4
LCD D6 pin to digital pin 3
LCD D7 pin to digital pin 2
LCD R/W pin to ground
LCD A pin 15 to Power 3.3V
LCD K pin 16 to GND
LCD VSS pin 1 to GND
LCD VDD pin 2 to Power 5V

More Information:

All the Pins on the LCD

  • VSS, VDD, VO, RS, RW, E, DO, D1, D2, D3, D4, D5, D6, D7, A, K

Arduino:

  • ELEGOO UNO R3

Thanks for the help!

2

You are using the 1602 lcd and an Elegoo board, so I'm assuming everything is branded from Elegoo and you also have a tutorial (if not, download it here Elegoo Tutorials

Please follow their instructions (lesson 22), and everything will work fine.

Btw... I see you are not referring to any 10k resistor or potenciometer. It's implicit that you need them, as the Blink example you posted states clearly (it's in the description).

3

Yes I do have the Elegoo tutorial I just want it to appear Hello World! for testing. Also is there a way to directly connect this with jumper wires to Arduino and without 10k resistor or potenciometer, thank you for answering!

#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // 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(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis() / 1000);
}
4

The 10k/potenciometer is needed to adjust/have some contrast. Without it you'll see nothing: it's like printing white on white.

Follow the tutorial 22 if you don't trust your wiring. And yes, you absolutely need the resistor.

The easiest way to control the lcd without a bunch of wires and the resistor is by using an i2c adapter chip like this one i2c to lcd

5

Thanks for the help, I see what you mean with the potenciometer I just wanted no extra parts far as breadboards so I could move it around not stay in place. I will use a potenciometer or another type of screen thanks for everything!

6

If you do not have a potentiometer, just connect pin#3 (VO) directly to GND. This should give you a readable display.
Or try a 470R between VO and GND. Experiment with 0R, 220R, 470R, 680R and choose the best contrast.

Oh, if you ever want to buy a new 16x2, the I2C versions are cheap, work well, use less wires, ...

David.

7

When I wired the VO pin to GND ASCII -like white blocks ( █ ) appear on the screen also with the resistor, but I will keep experimenting to make it a appear thank you for letting me see this.

8

I found a potentiometer off of an another electronic and I attached it to the screen it works but it still shows on the white blocks on the screen

9

I finally got it to work after uploading the code , thanks for the cooperation and help from everyone thanks!

10

You should have a couple potenciometers and a bunch of resistors coming with your kit, am I right?

11

Yes it came with potenciometers but I couldn't find one. Also my LCD screen went back to only showing the white blocks and I can't upload code to the Arduino anymore as well, can anyone help me I really need the help.

12

You have, at your disposal, a kit with a 200+ pages tutorial, at least 120 resistors and at least 2 potenciometer... "I couldn't find one" is no excuse... look for them, buy them, ask for them. Salvaging electronics parts is no good (what range was the potenciometer you salvaged?). Messing with wires is even worse: just a few second of short circuiting will fry your board and your display.

Please FOLLOW THE TUTORIAL, LESSON 22, just once.

Btw, hoping that you din't make any irreparable mistake, please explain what you mean by "you can't upload the code".
Does Arduino IDE recognize the board?
Does the board's led blink when on?
Do you get any error message?
Is the cable connected in the correct port?

You ask, ask, ask for help, but it seems to me you are doing everything in your power in order to NOT HAVE a working project.

1 Like
13

Step202:
Yes it came with potenciometers but I couldn't find one. Also my LCD screen went back to only showing the white blocks and I can't upload code to the Arduino anymore as well, can anyone help me I really need the help.

If possible...... buy a few of these lcd modules. If you accidentally damage one..... or if you suspect damage.... then at least you have plan B.

14

I have used an elegoo board with 16x2 before as well, with the same code and it failed to work. by switching the same circuit to another board I got everything to work perfectly. The elegoo board could be at fault, but this is only a sample size of 2 so don't jump to conclusions.