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[Reply #30 on:]

Julien,
I think I have already answered all of your questions for case 1 - to the embarrassing extent that I sound like I'm promoting it.

You are, of course, free to try any method you like. Perhaps you should breadboard each on a small scale, and see what you like.

As for me, I will check out what it takes to write up what I know in the Playground and unplug from the matrix.

[Reply #31 on:]

I probably disturbed people with my posts... I'm sorry  :'(
But I'm a little bit lost.

Of course I'm free, as everyone of us, to try what I want to
But if I share, ask, write, the reason is: I need some help.
I studied your answers. Of course, I'm not a specialist of this domain of knowledge. So, I probably asked the same kind of questions more than one times...
please, be indulgent  8-)

so, what do you think about the last solution with the wiring board?
Is it a way?
I ask that in order not to damage my board & to share my ideas too

to the embarrassing extent that I sound like I'm promoting it.

I don't understand

[Reply #32 on:]

I am working on a sound project which would like to visualize as 8x8 LED matrix which can control the blinking frequency and intensity of each LED.
Since I am not a technical person and new to electronics stuff, just want to know the exact component and parts model that I have to buy in order to minimize the need for soldering:
1) 8x8 LED matrix
2) MAX7219 IC

any other wire or minor component that is required? thanks for your help

[Reply #33 on:]

besides for the MAX7219, there are no. of items, can anyone tell which one is the appropriate one?
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1339/t/or

thx

[Reply #34 on:]

Assuming "no. of items" means "part numbers", you probably want the MAX7219CNG+ or better yet, the MAX7221CNG+.

(The letters at the end refer to the package type (the above are DIP - not surface mount) and other things like the temperature range.)

[Reply #35 on:]

thanks Brohogan. Finally can order it..

regarding the LED matrix, I found two potential but the price is quite big difference, so I wonder which one is more suitable for LED as output.
dual color, small one:
http://www.sparkfun.com/commerce/product_info.php?products_id=681
serial interface, dual color as well:
http://www.sparkfun.com/commerce/product_info.php?products_id=759

any other parts I need to buy ?

[Reply #36 on:]

You don't need the "serial backpack" if you are going to drive the device with the MAX72xx. So you might want to look at the "medium" size . . .
http://www.sparkfun.com/commerce/product_info.php?products_id=682

The only other part you need are 2 resistors (~26k) and a few caps (~.1uF).

This old thread inspired me to write this all up on the Playground a while ago . . .
http://www.arduino.cc/playground/Main/MultiplexMAX72xx
[edit](fixed link)[/edit]

have fun

[Reply #37 on:]

um...seems with backpack I can more focus on the display of LED instead of the technical setup of the circuit board as a whole. It seems the backpack will the take care all the communication and control part.

thanks so much for your explanation, really help esp for someone who is really new in this field and not having an engineering bg.

[Reply #38 on:]

I can understand your point. If wiring up a board with over 80 connection points isn't something you want to do, than the backpack is a viable alternative.

I wonder if the LedControl library (http://www.arduino.cc/playground/Main/LedControl) could be adapted to run the backpack - or there might be something written especially for it already.

You also might want to look at this recent thread if you haven't already.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1225239439

It's 1 color, but there are sure a lot of them !

All the best on your project.

[Reply #39 on:]

hi,

I finally get my dual color matrix and max 7219, however I found no. of problem, anyone can help?

1) the matrix keeps on turn on for all the LED instead, may I know how to make sure my 7291IC is working?  ( i have tried to unplug the 3 digital pins, all the LED still light up)

2) I can see through the schematic of the LED matrix which defines as rows and columns, however there is no clear indication on how to top 12 pins and bottom 12 pins link to each row and columns.
Here is the note I got, want to make sure if this is correct:
photo: http://www.flickr.com/photos/siusoon/3244754471/
 
3) my code as below, but still all the light are on instead:
///////////
int CLOCK = 12;
int LATCH = 8;
int DATA  = 13;

/*int dataIn = 8;
int load = 13;
int clock = 12;
*/

byte matrix[8];
byte head;
int state = 0;

void setup() {
  pinMode(CLOCK, OUTPUT);
  pinMode(LATCH, OUTPUT);
  pinMode(DATA,  OUTPUT);
  digitalWrite(CLOCK, LOW);
  digitalWrite(LATCH, LOW);
  digitalWrite(DATA,  LOW);
  initLED();
  clearLED();
  Serial.begin(9600);
  head = (byte) 0x55;
}

void loop() {
  if (Serial.available()>0) {
    int input = Serial.read();
    switch (state) {
    case 0:
      if (input==head) {
        state = 1;
      }
      break;
    case 1:
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
    case 7:
      matrix[state-1] = (byte) input;
      state++;
      break;
    case 8:
      matrix[state-1] = (byte) input;
      state = 0;
      refreshLED();
      break;
    }
  }
}

void ledOut(int n) {
  digitalWrite(LATCH, LOW);
  shiftOut(DATA, CLOCK, MSBFIRST, (n>>);
  shiftOut(DATA, CLOCK, MSBFIRST, (n));
  digitalWrite(LATCH, HIGH);
  delay(1);
  digitalWrite(LATCH, LOW);
}

void initLED() {
  ledOut(0x0B07);
  ledOut(0x0A0C);
  ledOut(0x0900);
  ledOut(0x0C01);
}

void clearLED() {
  for (int i=0;i<8;i++) {
    matrix = 0x00;
  }
  refreshLED();
}

void refreshLED() {
  int n1, n2, n3;
  for (int i=0;i<8;i++) {
    n1 = i+1;
    n2 = matrix;
    n3 = (n1<<+n2;
    ledOut(n3);
  }
}

void updateLED(int i, int j, boolean b) {
  int t = 1;
  int n = 0;
  int m = 0;
  if (j==0) {
    m = 7;
  }
  else {
    m = j-1;
  }
  n = t<<m;
  if (b) {
    matrix = n | matrix;
  }
  else {
    n = ~n;
    matrix = n & matrix;
  }
}

////////////////////////

[Reply #40 on:]

I have tried with different 7219IC, same result found that means my IC should be working fine.

Still all the LED light up in two cases:

1) I just have 3 digital pins and GND connect with Arduino board
or 2) GND and 3V / 5V are connected with Arduino with the IC

anyone experience this? http://www.flickr.com/photos/siusoon/3245731401/

[Reply #41 on:]

o I have successfully wired up the LED finally, the reason for not working because I have just put the rows <-> map to SEG of IC instead. Now is working fine. Here is my testing video:

One more question is the IC is getting hot, is it normal? and how to avoid this? Currently I have put a 10m capacitor between the GND and V++.

[Reply #42 on:]

Happy to hear that.

What IC is getting hot? The MAX72xx?
If so what value of Iset are you using?

[Reply #43 on:]

Problem solved now too thanks alot!!