Thanks so much! I figured out how to light up individual rows of LEDs using row-column scanning AND using shift registers. Both methods work. The brightness isn't an issue at all.

I think I'm going to make a 3x3x3 RGB LED cube instead. It'll utilize about the same amount of LEDs as a 5x5 matrix, so I figure it shouldn't be an issue. I'm already about a third finished with the construction of the cube. I just need to know though, how do I control the different levels of the cube? Do you have experience with those? I came across an Instructable that uses transistors for that, but the schematic/instructions were very unclear: http://www.instructables.com/id/LED-Cube-and-Arduino-Lib/step4/Using-the-Software/. Any ideas? Thanks!

So I'm basically looking to do something like this, right?

Will my LEDs be as bright as his if I use only shift registers and nothing else?

What do you mean by daisy-chaining and piggy-backing, exactly?

Also, when you say "it's not guaranteed to last forever," what does that mean? How bright will it be?

What do you mean by "de-activating the output drivers"?

How would I wire all of this? Do you have a schematic? That would help IMMENSELY!

Remember that you're dealing with a real noob here. You're using a lot of terminology that is new to me. Having said that, I can't stress how grateful I am for your help. Thanks!

I can't get common anode LEDs; that isn't an option.

I'll put up another drawing once I get home.

What do you mean by three resistors per LED? I'm confused. Where on the schematic do they need to go? You mean that each anode pin on each LED needs a resistor?

Also, how much would the following ICs help with a project like this?
CD4067BE (http://www.alldatasheet.com/datasheet-pdf/pdf/157680/TI/CD4067BE.html)
74LS257 (http://www.datasheetcatalog.com/datasheets_pdf/7/4/L/S/74LS257.shtml)
74LS139 (http://www.alldatasheet.com/datasheet-pdf/pdf/8082/NSC/74LS139.html)
74LS251 (http://www.datasheetcatalog.com/datasheets_pdf/7/4/L/S/74LS251.shtml)

Oh hey madworm, are you the same madworm who made that RGB LED matrix on Instructables? I'm the one who posted that question about whether you had any schematics or photos of the circuit before you had your PCB made. lol.

To answer your questions:
- I had my LEDs powered by an external source of 6.4 V. I didn't measure the current. Where should I measure it on my circuit?
- No, they were all equally dim.
- I have one transistor for each color, but I have two LEDs connected to those transistors. It's all there in my schematic.
- I tried measuring the voltage across it. I took my multimeter and put the probes to the resistors while the circuit was being powered. Nothing happened. I tried taking out one leed of the resistor and sticking a wire in its place instead, then measuring the voltage between the two. The LEDs got really, really bright when I did that. Then once I took the probes away, the LEDs got even dimmer. They don't even light up now, except for when I touch one of the transistors or resistors. Then they get really, really bright.

I have no idea what's going on.
Could I use something like this to power my matrix instead? http://arduino.cc/en/Tutorial/RowColumnScanning or multiplexers or shift registers?

Hi everyone,

I have a project that's due on Tuesday. I was going to make a 5x5 RGB LED matrix powered by the arduino (and connect it to shift registers), but I just realized that I'm going to need something to drive the current to the LEDs. I tried using PNP transistors to do this (see the schematic I attached), but then the LEDs went really dim. I really don't know what to do. Please help me out—it's my final project and it's due Tuesday! Thanks!!

I have a sharp IR sensor, a push button and some LEDs connected to my arduino. I'm trying to write a program in which the sensor collects data and sends it to the LEDs, but the user has the option of turning off the lights entirely using a push-button switch. I also want to create an option using another push-button in which the user can press it and the LEDs will retain that particular brightness. Basically, I'm trying to make an LED flashlight in which the user can control the brightness using the sensor.

Here is my code so far. It's a school project, so it's due very soon. Please help me out! Thanks!


int debounce = 10;            //length of time to debounce switch in milliseconds
int ButtonValue;              //used to feel current button state
int LastButtonValue = LOW;    //used to remember last button state
int PushButton = 2;
int led = 9;

double y;
int analogPin = 4;
int val;
//assume unpressed button at startup
int state = LOW;

void setup()
{
  pinMode(led, OUTPUT);        //sets the LED pin as output
  pinMode(PushButton, INPUT);  //sets PushButton pin as input
  Serial.begin(9600);
}

void loop()
{

  ButtonValue = digitalRead(PushButton); //digitally reads value of PushButton into variable ButtonValue
  if (ButtonValue == HIGH && LastButtonValue == LOW){
    delay(debounce);         //wait long enough to know that the input is real
    ButtonValue = digitalRead(PushButton);
    if (ButtonValue == HIGH && LastButtonValue == LOW){
      Serial.print("pressed ");
      state = !state;
      digitalWrite(led, state);  //toggle the LED
      Serial.println(state);

      if (ButtonValue != LOW){

        val = analogRead(analogPin);    // read the sensor's data
        Serial.print("Analog value =\t");
        y = (772.92 * 9.723 * 1/(val))*(5/2.5); //this equation linearizes the sensor data
        Serial.println(y);
        delay(500);

        analogWrite(led, y);
      }

    }
  }
  LastButtonValue = ButtonValue;  //make a note of the state we're in for
}

Okay, I just found this post on the Sparkfun forums: http://forum.sparkfun.com/viewtopic.php?t=8475 apparently you need to hook up another power supply to the lilypad even when it's connected to the computer? I tried connecting a 5V power supply to the lilypad, and the LED on the board blinked, but then I received this message:

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding

What could this mean?

Hello,

I recently purchased a lilypad arduino (ATmega 328) and an FTDI cable (this one: http://www.sparkfun.com/products/9718). I just reinstalled the arduino software just in case I hadn't previously installed the necessary FTDI drivers. However, I keep encountering the following message every time I try to upload code:

Problem uploading to board.
avrdude: stk500_getsync(): not in sync: resp=0x30
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

I'm running OS X 10.6.7. I think it might be a driver issue. Also, the board doesn't light up when I plug it into my computer. Does anybody know what's going on? Please help! Thanks!

Thank you so much, Don. I really appreciate all your help. I have a few questions:

1. In that code that you posted, where do I specify the characters that I want to output? Is there any way you could actually give me a sample program (not too complicated) that works on this particular module?

2. For some reason, whenever I output data to the LCD, there are always a bunch of random bits of data that show up beforehand. For this reason, I cannot output anything static to the LCD, because the random bits just stay there and never go away. Why are those random bits there, and how can I make those go away? In case you don't know what I'm referring to, I attached an image to this message.

3. I was thinking that perhaps the approach I want to take to make this animation is one in which I output a series of static images using custom-made characters—as opposed to moving the cursor around. How do I do this? I put the data in void setup() as opposed to void loop(), so that they would stay still, but then I ran into that annoying problem with the random characters. I was thinking of running through my images using a loop or an array, but how would I do that?

Thanks so much!

Yes, but how do you implement a command like the reset cursor position command? This is what I typed:

  Serial.print(254, BYTE);
  Serial.print(69, BYTE);//change cursor position

But then how do you indicate WHERE you want the cursor to go or what character you want to move?
Also, where in the link that you posted does it tell you how to make the ASCII characters move across the screen?

I tried playing with the "set cursor" command and I haven't really figured it out. If I operate this device in i2c mode, then can't I use the LCDi2cNHD (on this page: http://www.arduino.cc/playground/Code/LCDAPI) library? It says on the datasheet that I need to place a jumper on R1 and put pull-up resistors on R7 and R8 (this is all on page 6 of this datasheet: http://www.newhavendisplay.com/specs/NHD-0220D3Z-NSW-BBW.pdf); however, there are no holes next to them…do I need to solder wires to the board itself? Is there a way to expand my options while still in RS232 mode?

Also, are there any special libraries for this thing? It has its own microcontroller, so I figured the LiquidCrystal libraries wouldn't work.

Okay, thanks a whole lot. I managed to get the device turned on, and I'm able to transmit data by outputting the decimal numbers that correspond to each ASCII code. I also figured out how to get some of the special commands to work.

However, I need to make an animation for this thing. How can I make characters move wherever I want on the screen? Like, suppose I want to make a character jump from cell 1 on row 2 to cell 15 on row 1? How would I do that?

Thanks!

Hello,

I need to make an animation that will be displayed on this Newhaven 0220D3Z LCD display: http://media.digikey.com/Photos/Newhaven%20Display%20Photos/MFG_NHD-0220D3Z-NSW-BBW.jpg. Being a noob at this and all, I have a few questions:

1. How do you read the pin connections, exactly? The pin numbers and the function that corresponds to each pin number are listed in the datasheet, but the holes on the board themselves aren't labeled. Here is the datasheet: http://www.newhavendisplay.com/specs/NHD-0220D3Z-NSW-BBW.pdf

2. Why are there two VDD and GND inputs? Do you need to use both?

2. What commands do you use to send bits of data to this thing? Do any of you have experience with this? What do I need to do, code-wise? (I'm a REAL noob with all this).

Thank you so much!