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Topic: another lcd 16x2 display not working (Read 4159 times) previous topic - next topic

murrcat

I know, I know, another one, but I think everything is correctly set up. The contrast (used 10K pot as recommended) and backlight work. The RS and Enable pins are in the correctly connected to the Arduino as are the D4 thru D7 pins. The lcd used HD44780 parallel interface chipset as seen at http://www.sparkfun.com/products/255.
The code is exactly what's on the arduino.cc website:  All the tutorials I've seen were with previous versions of the Arduino. I'm using an Uno. Is there something different (extra code) that needs to be added?
#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);
}

liudr

Try this, be patient with it:

http://arduino.cc/forum/index.php/topic,102266.0.html

BTW, what is that thing in your picture?

murrcat

Sorry wrong picture. I had already read that post and checked off all of the potential errors.
(Previous picture was of broken breakout units. Different issue.)

liudr

It's a bit hard to trace the wires from point a to point b. That's what we need to make sure you wired everything right.

From the screen, your both lines are off on the contrast. If you turn one of the pots (why are there two and how are they hooked up?), does the contrast change? You want to turn the pot so that you don't see the dark shade on the display.

floresta

It looks like pin 2 is not soldered.

Don

murrcat

Sorry about the fuzzy picture. I took it with my phone.
Pin 2 is soldered. It goes to 5v and there is power to the display.
When I turn the pot for the contrast, it definitely changes, going from a dark screen to seeing two rows of blocks.
The two pots are just for the heck of it. One was for the backlight, but I don't need it. I just used it to rule out that not having it wasn't the problem.

floresta

Quote
When I turn the pot for the contrast, it definitely changes, going from a dark screen to seeing two rows of blocks.


That's not normal or your description isn't correct.  Try it again with the six LCD <--> Arduino wires disconnected.

Don

murrcat

The contrast with the variable resistance goes from dark to light. Isn't that what is supposed to happen?

floresta

Quote
The contrast with the variable resistance goes from dark to light. Isn't that what is supposed to happen?


Could you be a little more specific?  What do you see with the pot at one end?  What do you see with the pot at the other end?  Where did you wind up leaving the pot set?  Can you measure the voltage between pin 3 and ground at that setting (and tell us what voltage you measured)?

Don

Try this connection. Sometimes can be hard to word with a LCD display.
http://telecoreference.wordpress.com/2012/03/08/arduino-lcd-display-hd44780/

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