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1  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 12, 2011, 11:40:10 am
So I'll be the first person to tell you that my soldering skills are abysmal. I'm a software guy, and I haven't done much soldering in my time. I decided to just re-do my soldering, and look:

Brilliant! I should be able to apply it to my project. Thanks again for all your help.
2  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 12, 2011, 09:49:23 am
floresta - looks like I did have a wiring error in the video. I've fixed it since and I still get the same behavior

polishdude20 - I've tried both of the things you've suggested, and I still get the same thing.

I've uploaded another video of my setup, which is now modeled after your tutorial, in case it makes any difference.

Thanks for your help.
3  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 11, 2011, 11:41:47 pm
I tried it with and without the setCursor call, same behavior. I also tried hooking it up in 8-bit mode and I didn't get anything different, and all combinations of lcd.begin() with 16/20 and 2/4.

At one point, I managed to get a bunch of scrolling garbage characters on the screen for a few seconds instead of just a blank display, but I haven't been able to reproduce that behavior. For a moment I thought my LCD might not be broken, but that's what it's looking like to me.

Any more ideas?
4  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 11, 2011, 07:13:06 pm
  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 (
 example added 9 Jul 2009
 by Tom Igoe
 modified 22 Nov 2010
 by Tom Igoe
 This example code is in the public domain.

// 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(20, 4);
  // 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:

I've tested the connections as much as I can and I haven't found anything wrong, but don't know of a way to be POSITIVE that they're good... I suppose if everything else can be eliminated, that must be it, right?
5  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 11, 2011, 06:29:42 pm

The red numbers mean that the pins go to the corresponding pins on the Arduino. "wiper" means that it goes toward the wiper of the potentiometer.
6  Using Arduino / LEDs and Multiplexing / Re: Is something wrong with my LCD screen? on: March 11, 2011, 05:45:25 pm
Thanks for your help.

The display is 20X4 instead of 16X2. I've tried adjusting the lcd.begin statement to account for that but I get the same results.

There are 16 pins on my LCD, not 20 -- I've seen LCDs with 14 pins, without the extra two on the right that control the backlight, but other than that it looks to be the same as other LCDs that I've seen examples of, and they use the LiquidCrystal library. There are even labels on the pins (underneath where the header is on the video) that match up with all of the code examples I've seen.

This is the type of LCD I have:

It comes with a tutorial, but no datasheet. Here's a link to the tutorial:

In that tutorial, there is a code sample that uses the LiquidCrystal library to drive the LCD, it's not all that different from the HelloWorld example I've been using. I've tried using that code example and I get the same results.

Are you sure it's not a problem with the library? Even if it was, I'm not sure where I would go to find a different one...
7  Using Arduino / LEDs and Multiplexing / Is something wrong with my LCD screen? on: March 11, 2011, 05:13:57 pm
I just got an Arduino and an LCD screen, and I can't seem to get the LCD to display anything. I've tried getting the HelloWorld demo to work, the one that comes with the Arduino software under the LiquidCrystal library. I've made a video of my setup, and I've also taken a closer picture of my soldering.

I'm able to get the backlight to work, and it looks like the contrast is working. What could be my problem here?
8  Using Arduino / Project Guidance / Re: Aquarium LED light controller on: March 01, 2011, 07:28:00 am
Thanks for your help, I appreciate it.
9  Using Arduino / Project Guidance / Re: Aquarium LED light controller on: February 28, 2011, 07:28:45 pm
I spent an hour on and another hour with google trying to find a similar project, and trying to find out what the specs on the Arduino are. Excuse me if I didn't have the right combination of keywords, but you don't need to be rude about it.

Every microcontroller I've ever used only has a fixed number of output pins that support PWM, which is why I asked.

Seems like my project is feasable. Thanks for answering my question. I hope it comes with datasheets/instructions, since even though you've given me crap for not having looked, I still don't know where to find that information.
10  Using Arduino / Project Guidance / Aquarium LED light controller on: February 28, 2011, 04:06:19 pm
I'm wanting to make an LED setup for an aquarium. I'm thinking about using an Arduino to be the controller, but I can't find any of the specs on the website so I can't be sure if the Arduino will do everything I need.

I want to have the same lighting schedule every day, so it would go on a 24-hour repeat. Doing something like this shouldn't be a problem from what I've seen.

I want to have four separate channels, I could possibly get by with three, but I'd really like to have four.

I have no idea what kind of outputs the Arduino has -- does it support PWM (Pulse Width Modulation)? I'm thinking this would be the best way to control the brightness since I would like to have fade in/fade out capabilities -- I could just slowly increase the duty cycle over the course of 30-60 minutes. If so, does it have four separate pins I could use for outputs? What are the output voltages/other specs for these pins?

I have my eyes on some LED strips that were made to put into a car (ie, plug into the 12V DC cigarette lighter thing), and I was thinking about using a BuckPuck or something similar to drive those LEDs, but that hardware hasn't been bought yet so it's still flexible.

Is this project feasible with an Arduino? Thanks in advance for your help,

-Adam Horton
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