Faulty user or faulty LCM1602C? Please help a newbie ^^"...

Other Hardware Displays
1

Hello everyone, I'm sorry to bother but I wondered if anyone could help ^^" - I have purchased the arduino starter kit a week ago on amazon (they were out of stock on the arduino website ... So a dozen euros extra wasn't that harsh =S) and I can't find a way to get the provided LCD working ..

The tutorial in the book didn't help so I started browsing ... I stumbled upon this tutorial but no result, I checked the wiring over and over again, the only difference between my LCD and the one in the tutorial is the "VCC" pin that is engraved "VDD" on my display - but i guess that it must be the same thing (hoping that i'm not wrong) - All I'm managing to get working is the the backlight (that I can barely dim at all using the 10Kohm pot), no text whatsoever - I have checked the pins in the software too (2,3,4,5,11,12).

Pictures of my circuit

Is there any way to know if my LCD is faulty? It's the only component that I haven't managed to get to work so far and I was so stary-eyed at the thought of writing my own stuff on a backlit LCD ^^".
Halp?

Thanks in advance ^^
~a nice newbie

2

My original reply got gobbled up by the wonderful forum software. I hope I remember it all.

Your display is upside down so you may very well be interpreting the pin numbers incorrectly.

Most LCD modules have their pins above and to the left of the display and pin #1 is near the left edge. It looks like you are not powering pins 1 and 2.

The terms VCC and VDD are used more or less interchangeably even though they shouldn't be. The VDD on your display refers to the 'drains' of its FETs whereas VCC would be appropriate with bipolar transistors and VPP would be appropriate if your LCD had vacuum tubes.

The 10K pot has no effect on the backlight when it is properly wired to control the contrast voltage at pin 3 of the LCD. It affects the visibility of the display so it must be adjusted correctly (see below).

My suggestion is for you to remove all of your wires and start over following this outline:

Here is my generic step by step approach that should work:

(1) If the module has a backlight then get it working properly. This involves only pins 15 and 16 on your LCD module. Make sure to use a current limiting resistor if there is none on the LCD module.

(2) Get the power and contrast working properly. This involves only pins 1, 2, and 3 on your LCD module. You should be able to see blocks on one row of a two row display and on two rows of a four row display.

NOTE: The Arduino has not been used yet, except as a possible source for the power needed for the first two steps. Do not try to go any further until this is working. If you don't see the blocks then no amount of program code will help.

(3) Connect the LCD R/W pin (pin 5) to GND.

(4) Connect the six control and data wires between your LCD module and your Arduino.

(5) Upload your sketch and it should work.

If you still don't get a display then make sure that your wiring matches the numbers in the descriptor (or vice versa).

//LiquidCrystal lcd(RS, E, D4, D5, D6, D7);
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);      // put your pin numbers here

If you get a display but it is garbled or has some other problems then try again with a 'static' sketch, one that displays a simple message on the top row of the display and then stops. All of your code should be in setup() and loop() should be empty between the brackets.

If you are still having problems then we need to see a photograph of your setup that clearly and unambiguously shows all of the connections between your Arduino and your LCD module. We also need a copy/paste version of the code that you are actually using, not a link to the code that you think you are using.

Don

3

Since you have power supplied at only one end of the display and your backlight is illuminating, it clearly must be pins 16 and 15 to which you are applying power.

So leave the connections to those, remove all the other connections, connect power to pins 1 and 2, and the potentiometer to pin 3, adjust the potentiometer (it will be very near to the ground end) until you can actually see the "blocks", then make the other connections.

floresta:
My original reply got gobbled up by the wonderful forum software.

So, here's a critical hint:

If you get the "Broken" screen - as it so elegantly calls itself (I couldn't quite recall the name at first; no doubt a mental block! :frowning: - but I am getting it frequently over the last week or so and again tonight), do not move forward or back, click "reload" and answer to "Resend" the form data as often as necessary. It will be remembered by the browser and there is no other way to salvage the data given the absurdly unhelpful way the forum is coded.

4

The terms VCC and VDD are used more or less interchangeably even though they shouldn't be. The VDD on your display refers to the 'drains' of its FETs whereas VCC would be appropriate with bipolar transistors

The corresponding term for GND in a FET circuit is Vss (V Source) so a bipolar transistor circuit will have power
labeled Vcc & GND whereas a FET circuit will ussually have them labeled Vdd & Vss.

(ie; CMOS CD4050 IC, Gnd, pin-8 is labeled Vss on the datasheet. see attached pinout image)

Robert

CD4050.JPG

5

Sorry about that. I just answered his question.

Don

6

Sorry about that. I just answered his question.

So ? I'm not trying to answer his question, I am simply supplementing the information you gave him.
I simply added the part you left out. If you're going to describe the terms for a fet circuit you might as well include the
corresponding term for "GND" , which is Vss. Is there any reason why I shouldn't mention that ?

7

Is there any reason why I shouldn't mention that ?

Absolutely. Too much information tends to scare neophytes away. In many cases it is best to just answer the question.

Don