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Topic: Request Help with Interfacing LCD 162A with arduino (Read 4286 times) previous topic - next topic


I have just bought an LCD 162A and i am trying to interface it with arduino ,i wired the attached circuit as it iis and all i could get is the backlight,now display on the screen,can any one help me with how to interface the LCD 162A.


I have attached an image of what i am talking about.


RW, pin 5 on LCD, connect it to ground.

Pin 3 on LCD, the contrast, are you sure about that resistor value? Replace it with potentiometer to be sure contrast is set correctly so the characters are visible on LCD.

Have you used the HelloWorld sketch from LiquidCrystal? According to your first post, you should use this:
LiquidCrystal lcd( 12, 11, 5, 4, 3, 2);


yeah i have used the Hello world sketch from the liquid crystal,the resistors are 10k Ohms,i went further to ground pin 5,and its still the same problem.i have just bought a JHD162A LCD,and have tried interfacing it with arduino but all in vain,tried every possible thing but cant get it to display anything,I connected it exactly like this and ran the hello world code,but am just getting the backlights lighting,no display,i have tried grounding pin 5 of the LCD,still nothing,please help me get out of this state of quagmire,i have been doing the same circuit since yeaterday,at first i thought i had made a mistake in the connection,then i re-did everything but the same.I even thought i bought a faulty LCD,then went back and bought a new one but all the same.Sorry if this is a really stupid question! I really have no idea and so am asking


// 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:
That is the code i am using


Two problems I can see:

1) You didn't solder the pins to the LCD pin holes. This will result in very poor contact and you will not see it work. Please solder a row of male pins to the display and plug in back in the bread board.
2) You are not using a 10Kohm potentiometer on pin 3 so your contrast will not be set right. With wrong contrast, you won't see the texts even when they are indeed displayed on the LCD.

Do you have a 10kohm potentiometer?
Serial LCD keypad panel,phi_prompt user interface library,SDI-12 USB Adapter


I do have the same problem, I have done and rechecked the circuit. But no response. I'm using JHD 162A LCD with code in the lcd library. connections are correct (also tested with and without 10K pot).
I have tested with 3 LCD displays. The same problem. No display only backlight. :(   
please help.


same as above: do first everything until contrast can be adjusted. When you can adjust you can see dark blocks by setting high contrast. Then you can be sure that the signs will be shown. Dont think about sketch  or connections of pins, this comes after clearing the contrast thing. If you cant set to dark blocks, your contrast setting doesnt work. There are several reasons for this:
-do you have the datasheet for your lcd? No, not any similar but the correct one.
-can you see in datasheet what voltage is to use for contrast? It can be +5V, -8V, -15V and others. The same lcd can need +5V, but a version for extended temperatures can need a negative voltage. Only when you know what is needed you can set the contrast. If you cant get the info, you can try, but that is with risk. Setting -15V to a contrast pin that wants +5V can damage your lcd. So its ever better to find the correct info. If one has no other way than trying, use a serial resistor with about 5-8 k to limit the current
-do you know which pin has to get the contrast voltage? There are several variants, so its the same thing: look into datasheet...
Thats the 1st step. Until contrast works you can forget all other questions.


Feb 24, 2013, 05:06 pm Last Edit: Feb 24, 2013, 05:07 pm by floresta Reason: 1
I do have the same problem ...

Here are the steps that you should follow to get your display working, these steps are essentially the same as described in the previous post.
(1) Get the backlight working, this typically involves only pins 15 and 16.  Make sure it has a series current limiting resistor if it needs one.
(2) Get the contrast working, this involves pins 1, 2, and 3.  You should get a blank display with the potentiometer at one end, and some really dark boxes on the top line of your display with the potentiometer at the other end.  You should adjust the potentiometer until you can just barely see the row of boxes.  Do not proceed until this is working as described, if you do then you will just be wasting your time.
(3) Connect the LCD control and data lines to your Arduino.  Do not forget to deal with LCD pin 5 or the display will not work, it is typically connected to GND.
(4) Load your sketch and see if it works.

If your display still does not work you are not going to get any really reliable help until we have more specific information.  We need as much of the following as possible:
(1) A photograph that allows us to unambiguously follow each wire from one end to the other.
(2) A copy of the sketch that you are using.
(3) A link to the datasheet for the display.
(4) A description or photo of the results of running your sketch.



Hi Guys,
I have a similar problem, except for two things:
1) Mine used to work perfectly and then one morning it didn't work anymore.
2) At the full contrast setting of the pot, I see only 8 squares instead of the usual full screen.

My setup can be seen in the image attached. I am using a displaytech 162A, 10k pot and wiring done as per above. (except that I have used 3.3V for my back-light since that is in accordance with the manufacturer specifications. I have tried using the hello world sketch as well as my own.

Have I somehow popped my screen?
Any advice would be greatly appreciated.



Feb 26, 2013, 06:53 pm Last Edit: Feb 26, 2013, 06:57 pm by floresta Reason: 1
I have a similar problem, except for two things:

I think your problem is quite different.  Try pressing down on the bezel of the display and see if that fixes things.

(except that I have used 3.3V for my back-light since that is in accordance with the manufacturer specifications.

You have misinterpreted the manufacturers specifications.  You must drive the backlight LED from a supply that is greater than the VF Max that corresponds to your backlight color.  Then, when you use the correct size current limiting resistor, one that will give you an IF near the Typ value, you will find that the voltage you measure across pins 15 and 16 are near the VF Typ value. I would start with 5 volts and a 100 ohm resistor in your case.



Hi Don,

Thanks for your quick response. Apologies for my ignorance. I have adjusted the wiring for the back-light as per your advice and that appears to work well.
Pressing down on the bezel does not seem to make any difference. What is it that you suspect might be wrong with it?



That type of problem is sometimes caused by a poor connection between the LCD glass and the traces on the PC board and I had to do some research to come up with the correct terminology.  The LCD glass is connected to the PC board by means of an 'Elastomer Connector' (http://en.wikipedia.org/wiki/Elastomeric_connector).  It is the bezel which provides the pressure to make a secure connection so when you press on the bezel you can sometimes fix the problem.


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