Hi,
I have tried following several tutorials and YouTube videos to get my starter kit LCD to display 'hello world'. I am now following the adafruit tutorial and when reaching the step of getting a single row of blocks across the display. I am getting a fading display showing some blocks across both display lines. It is difficult to photo as I think I am getting a bad connection in the breadboard, which is not giving a stable output display. Is this display broken and should I be getting a replacement from the company I ordered the starter kit from. The kit is only two weeks old and this is the first time I have used the display.
Thanks in advance
That does look faulty to me, you should have one row of blocks, not 2. And they should be solid.
You've only connected power and the pot for contrast. Too soon to say it's good or faulty. Carry on and get the data connected and some code running, see what happens.
Thanks for the replies. I have tried with code including the hello world code from arduino library and that's all I get out of it. The adafruit tutorial says I should see a full row of blocks and if you don't see that, don't carry on until its sorted.
ridehavoc19:
Thanks for the replies. I have tried with code including the hello world code from arduino library and that's all I get out of it. The adafruit tutorial says I should see a full row of blocks and if you don't see that, don't carry on until its sorted.
Can you clarify that? You don't show any wiring for data so without wiring you can run all the code in the world, it's not going to display anything.
Appreciate that there is no data wiring but the steps in the tutorial I am following do the set up in broken up steps and this step should produce a single row of blocks on one of the display lines, when wired with data cables the display still shows the same output. I will wire it again for a photo tomorrow but it won't show anything more than has been shown here, at this step.
The tutorial I am following is this,
The screen shot shows only 5v, Gnd and the pot and expected output
Fully wired with data cables. No display at all, I can't even get the blocks from earlier photos by turning the potentiometer. The code I have been using is,
#include <LiquidCrystal.h>
// initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
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);
}
Contrary to the comments in replies 2 and 4 the instructions in the tutorial are correct.
In troubleshooting your LCD you should start with only the backlight, power, and contrast pins connected. You don't want or need any code running. You don't even need the Arduino if you have a 5v power supply.
If you get a single row of blocks as shown in the lower right photo of reply #5 your display is functioning properly and you can add the rest of the wiring and the code in order to display a message.
If your display is blank or if both rows of blocks are full you may have the potentiometer set incorrectly. Try connecting pin 3 directly to GND instead of to the potentiometer.
If your display looks like screen 1 (2).jpg your display is defective.
Don
Many thanks, I will try connecting ground to pin 3 later on today and see what happens.
Not looking promising then. Make really, really sure your wiring is correct. Connections through breadboard are not 100% reliable, not are those plug ended wires. 1 faulty connection will give you problems.
Don't worry about the small disagreement between Don and me, he knows what he's doing and I think I do, we just have slightly different approaches.
I am inclined to think you probably have a faulty display though.
Please edit your code in reply #6 to include code tags </> so it's formatted as code and easier to read as per the forum instructions.
Will wire it up from scratch again after work today. I have had a few issues with the plug ended wires already. Some of them when tested fail continuity so have been testing each one with a multimeter before use and throwing the broken ones away. I will try wiring it with solid jumper cables and see if the result changes. I have (hopefully) correctly edited the code for viewing in the post as suggested.
Actually, while connecting pin 3 - "Vo" - to ground is a method of testing, the more important message is - do not connect the potentiometer to Vcc - 5 V. This is a longstanding mistake copied mindlessly through tutorials and supposedly "professional" designs. If using a 10k potentiometer, it is actually practical to connect both ends of the potentiometer to ground to make it more closely resemble the proper value of 1 or 2k.
Yes, do start again wiring only pins 1 to 2, 15 and 16, but with the correct potentiometer wiring. Sadly even Adafruit, who are otherwise extremely reputable - have not corrected this mistake. 
I have both 1k and 2k pots. Would I be better to ditch the 10k supplied in the starter kit and use one of these with just (if I understand correctly) one pin connected to ground with no 5V vcc input?
If that is correct, why use a pot at all? Would a fixed resistor not do the same job. I am sure there is a sensible reason to use a pot that I don't know of, but as this is about learning I have got to ask the question?
ridehavoc19:
I have both 1k and 2k pots. Would I be better to ditch the 10k supplied in the starter kit and use one of these with just (if I understand correctly) one pin connected to ground with no 5V Vcc input?
Yes, that makes the contrast setting easier - you spread the workable adjustment over a wide area of the potentiometer range.
This corresponds more closely to the diagram on page 37 of the HD447080 datasheet (the reference to -5V relates to displays working at lower temperature and requiring a greater contrast voltage - in this case that point is ground.).