SCM1602A-V3 LCD problem

Dear all,

I bought SCM1602A-V3 LCD (16x2) from Internet, I tried to show a simple HelloWorld on the panel, but only show the several black blocks. Please help to fix this issue. Thanks.

IMG_5822.JPG

IMG_5823.JPG

Sample code is here.

/*
LiquidCrystal Library - Hello World

Demonstrates the use a 16x2 LCD display. The LiquidCrystal
library works with all LCD displays that are compatible with the
Hitachi HD44780 driver. There are many of them out there, and you
can usually tell them by the 16-pin interface.

This sketch prints “Hello World!” to the LCD
and shows the time.

The circuit:

  • 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
  • 10K resistor:
  • ends to +5V and ground
  • wiper to LCD VO pin (pin 3)

Library originally added 18 Apr 2008
by David A. Mellis
library modified 5 Jul 2009
by Limor Fried (http://www.ladyada.net)
example added 9 Jul 2009
by Tom Igoe
modified 22 Nov 2010
by Tom Igoe

This example code is in the public domain.

http://www.arduino.cc/en/Tutorial/LiquidCrystal
*/

// include the library 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() {
// 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);
}

Your problem is most likely due to an improper connection or a bad wire.

You have provided nice clear photographs but unfortunately I cannot determine if your wiring is correct since the data wires are all the same color and they are twisted around one another.

You should pull out the orange and the white wires and redo that portion of the wiring. I suggest using different wires. Check them for continuity first and use different or at least alternating colors on the data connections. Also check to make sure that pin 5 of the LCD (the blue wire) is making a good connection to GND.

Don

The two white wires don't look like they are going to 11 and 12...They are going to 12 and 13. That will not help...

Dear all,

Thanks for your support.

By the way, I reconnected my wires. I found a strange thing. I do not connect to D4~D7, but LCD panel still displays black blocks.

Next, I connected D4~D7 to pin 5~ pin 2 by alternating colors (for clear view), but the result is the same.

What happens if you just connect the power and turn it on and off?

try varying 10K pot..

By the way, I reconnected my wires. I found a strange thing. I do not connect to D4~D7, but LCD panel still displays black blocks.

That is the ultimate version of the ‘improper connections’ that I mentioned in reply #2 and is perfectly normal.

Don

try varying 10K pot..

Why do this? The photos show that the contrast is properly set.

Don

@chenblack

Did you check your wires for continuity?

If you don't have an ohmmeter you can take the wire that you want to check and temporarily use it in place of the blue wire going to the backlight on pin 16. If the backlight still works then the wire is good.

Don

Hi Peeps. I also had issues getting the LCD to work. As other member have said the row of black blocks is due to incorrect wiring. I have attached my solution which should work for most peeps.

Hope this helps,

Regards, Shaun

The PIN numbers refer to the Arduino boards. The references in ( ) refer to the LCD. There is a typo on my diagram- PIN -5 should connect to D5 (pin 12) on the LCD

I have attached my solution which should work for most peeps.

You have misinterpreted the problem.

Your solution is nothing more than a sketch of one possible wiring scheme.

The "incorrect wiring" to which we refer is not a matter of having an incorrect schematic or wiring diagram, it is a matter of not following that diagram properly or following it properly with defective jumpers or defective soldering.

Don

Having played around with the same issue Chenblack had, and looking at his photographs he seemed to going down the same dead end route of getting the LCD to work, that I did. The solution I posted has served me well. I have tried this with several generic versions of the 16 x 2 LCD's and, so far this seems to work every time for me in simple applications.
Obviously there are many ways to address these LCD displays and I agree that many factors including which Library is being used for the LCD an affect this, however the fact remains that I have found this diagram has helped several people I know out of trouble and their LCD's working.
I was sharing what worked for me, so I guess only Chenblack can comment if my method worked for him, or defective jumpers / soldering was his problem.

Regards, Shaun

OK. Please explain to me what is so special about your diagram and how it can work when others don't.

It obviously can't be the choice of series dropping resistor for the backlight since the presence, absence, or misadjustment of the backlight will have no affect on the operation of the LCD controller.

It can't be your choice of a fixed resistor for the contrast adjustment since his contrast is adjusted properly as evidenced by the photographs.

It can't be your choice of Arduino pins to use for the LCD since any Arduino pin can be used to drive any of the LCD pins.

I don't recall running into a case where an LCD that could display the row of black rectangles ultimately turned out to have a defective controller so I doubt that is the problem.

So what is it about your magic diagram that makes it so special?

The bottom line is that his wiring probably still has a problem. One or more of his wires most likely is defective or possibly mis-located. His earliest photographs show the RS and E lines connected to the wrong Arduino pins but that appears to have been corrected in the later photos.

Don

chenblack:
Dear all,

I bought SCM1602A-V3 LCD (16x2) from Internet, I tried to show a simple HelloWorld on the panel, but only show the several black blocks. Please help to fix this issue. Thanks.

Hi I need this display, 1602A-v3, where can I buy it? Thank you so much Riccardo.

Where one could buy it four years ago and where one could get one today are entirely different questions.

Is there some reason why you need that particular display and why any other generic 16x2 display wouldn't suffice?

Don