3x3 led cube by a n00b

marzban123 · November 21, 2011, 4:59am

Hello everyone,
this is my first post here on the arduino forums. I just got my first arduino a week ago and i have almost no programming knowledge so bear with me.

i am aware that there is a forum for multiplexing and multiple leds, but my question is not so much about that, so thats why i have it here.

i know you are going to laugh when you see my code, but basically i have my cube set up like this:

i built a 3x3 cube and i have it so that each layer, or you could say plane, has a ground that is separate from the other layers. then, i have all of the anodes are connected to in collums. so basically i have 3 negative contacts and 9 positive contacts. since there is only one ground on the arduino, i used three transistors each connected to a different pin, to switch the ground between layers. i have the 9 columns connected directly to the 9 remaining pins on the arduino.

here is a diagram of my setup

and here is a picture

based on this setup, here is how my code turned out in order to light up the bottom layer of leds

                    digitalWrite(lev1,HIGH);     //lev1,lev2, and lev3 refer to the pins that are connected to the transistors
                    digitalWrite(lev2,LOW);      // to provide a ground to each of the layers
                    digitalWrite(lev3,LOW);
                    
                    digitalWrite(led1,HIGH);     //led1 to led9 are the pins that connect to each column 
                    digitalWrite(led2,HIGH);
                    digitalWrite(led3,HIGH);
                   
                    digitalWrite(led4,HIGH);
                    digitalWrite(led5,HIGH);
                    digitalWrite(led6,HIGH);
                    
                    digitalWrite(led7,HIGH);
                    digitalWrite(led8,HIGH);
                    digitalWrite(led9,HIGH);

with this code you can figure that the the entire bottom plane of leds would light up.
but, lets say i wanted one led in the bottom level to light up and an led on the second level to light up that is in a different column. well, with my setup i would have to turn on the ground to both level on and two and if i turn on any of the led pins, all of the leds in that column would light up.
so, here is what i did

                    digitalWrite(lev1,HIGH);
                    digitalWrite(lev2,LOW);
                    digitalWrite(lev3,LOW);
                    
                    digitalWrite(led1,HIGH);
                    digitalWrite(led2,LOW);
                    digitalWrite(led3,LOW);
                  
                    digitalWrite(led4,LOW);
                    digitalWrite(led5,LOW);
                    digitalWrite(led6,LOW);
                   
                    digitalWrite(led7,LOW);
                    digitalWrite(led8,LOW);
                    digitalWrite(led9,LOW);
                  
                   delay(5);

                    digitalWrite(lev1,LOW);
                    digitalWrite(lev2,HIGH);
                    digitalWrite(lev3,LOW);
                    
                    digitalWrite(led1,LOW);
                    digitalWrite(led2,HIGH);
                    digitalWrite(led3,LOW);
                  
                    digitalWrite(led4,LOW);
                    digitalWrite(led5,LOW);
                    digitalWrite(led6,LOW);
                   
                    digitalWrite(led7,LOW);
                    digitalWrite(led8,LOW);
                    digitalWrite(led9,LOW);
 
                    delay(5);

the leds light up individually with out all of the leds in the column lighting up. and with a delay that short you dont notice it flash back and forth

this is were my problems lie:

i have each pattern defined as a function, for example sequence1() is a pattern sequence2() is a different pattern.
i want my arduino to cycle through the patterns (after a set time, not by user input) and i need it to repeat the pattern/function until it goes to the next one.

here is what i have tried

  unsigned long time=millis();               
  unsigned long lasttime=0;            
  unsigned long x;                            //the difference between time and lasttime will be stored in x
  int seq;                                     // this will tell the loop which function/sequence to run

void setup()
{

seq=1;                                                    //i want to start with the first sequence
lasttime=0                                                //last time will be 0     
                                                          //here is where i have all of my patterns 
void sequence4()
{
                    digitalWrite(lev1,HIGH);         // this is an example of one pattern 
                    digitalWrite(lev2,HIGH);
                    digitalWrite(lev3,HIGH);
                    
                    digitalWrite(led1,HIGH);
                    digitalWrite(led2,LOW);
                    digitalWrite(led3,LOW);
                    
                    digitalWrite(led4,LOW);
                    digitalWrite(led5,HIGH);
                    digitalWrite(led6,LOW);
                    
                    digitalWrite(led7,LOW);
                    digitalWrite(led8,LOW);
                    digitalWrite(led9,HIGH);
                    
                    
                    delay(val);
                    
                    
                    digitalWrite(lev1,HIGH);
                    digitalWrite(lev2,HIGH);
                    digitalWrite(lev3,HIGH);
                    
                    digitalWrite(led1,LOW);
                    digitalWrite(led2,HIGH);
                    digitalWrite(led3,LOW);
                    
                    digitalWrite(led4,LOW);
                    digitalWrite(led5,HIGH);
                    digitalWrite(led6,LOW);
                    
                    digitalWrite(led7,LOW);
                    digitalWrite(led8,HIGH);
                    digitalWrite(led9,LOW);
                    
                    
                    delay(val);
                    
                    
                    digitalWrite(lev1,HIGH);
                    digitalWrite(lev2,HIGH);
                    digitalWrite(lev3,HIGH);
                    
                    digitalWrite(led1,LOW);
                    digitalWrite(led2,LOW);
                    digitalWrite(led3,HIGH);
                    
                    digitalWrite(led4,LOW);
                    digitalWrite(led5,HIGH);
                    digitalWrite(led6,LOW);
                    
                    digitalWrite(led7,HIGH);
                    digitalWrite(led8,LOW);
                    digitalWrite(led9,LOW);
                    
                    
                    delay(val);
                    
                    
                    digitalWrite(lev1,HIGH);
                    digitalWrite(lev2,HIGH);
                    digitalWrite(lev3,HIGH);
                    
                    digitalWrite(led1,LOW);
                    digitalWrite(led2,LOW);
                    digitalWrite(led3,LOW);
                    
                    digitalWrite(led4,HIGH);
                    digitalWrite(led5,HIGH);
                    digitalWrite(led6,HIGH);
                    
                    digitalWrite(led7,LOW);
                    digitalWrite(led8,LOW);
                    digitalWrite(led9,LOW);
                    
                    
                    delay(val);
                    
                    
}
}

void loop()                                                          // i think this is where my problem is
{

x=time-lasttime;

if(x==3000)                                                         
  {
    seq=seq+1;                                                    //after 3 seconds, increase seq by 1, and make lasttime equal to the current time
    lasttime=time;
   }

if (seq==1)
 {
   sequence1();
  }

if (seq=3)
  {
   sequence3();
   }

}

what am i doing wrong?

CrossRoads · November 21, 2011, 6:04am

A simpler way might be to write the patterns as elements in an array

so maybe like this

byte cathodes[3] = {2,3,4};
byte ledPins[9]={5,6,7,8,9,10,11,12,13};
 // declare these as outputs in setup
byte x; // used in counters
byte y;
byte z;
// sequence of 3 patterns to be written
byte 9x9Array[9][9]={
  {1,1,1,0,0,0,0,0,0}, // will be level 1; row 1,columns 0-8
  {0,0,0,1,1,1,0,0,0}, // level 2
  {0,0,0,0,0,0,1,1,1}, // level 3
  {0,0,0,1,1,1,0,0,0}, // will be level 1
  {0,0,0,0,0,0,1,1,1}, // level 2
  {1,1,1,0,0,0,0,0,0}, // level 3
  {0,0,0,0,0,0,1,1,1}, // will be level 1
  {1,1,1,0,0,0,0,0,0}, // level 2
  {0,0,0,1,1,1,0,0,0}, // level 3
};
void setup(){
// declare the output pins
} // end void setup
// then in loop:
void loop(){
for (z = 0; z<3; z=z+1){
    for (x = 0; x<3; x=x+1){ // cycle thru the layers 0,1,2
        for (y = 0; y<9; y=y+1){  // cycle thru the LEDs, 0-8
        digitalWrite (ledPins[y], 9x9array[z+x][y]); // so write to the pins 5,6,7,8... with the data at 9x9array[rows][columns]
        }  // end writing the 9 columns
       digitalWrite(cathodes[x], HIGH); // turn on the ground
       delay (100); // hold the displayed pattern a bit
       digitalWrite (cathodes[x], LOW);  // turn off the ground
    } // next row
}  // next set of rows
} // end void loop

anatolyk69_gmail.c · November 21, 2011, 8:49am

Do you have a current limiting resistors (9 overall) ?
I'm not sure you can declare: unsigned long time=millis();
Probably, better just: unsigned long time;
and initialize it it in the setup: time=millis();

marzban123 · November 21, 2011, 5:08pm

i could use an array, however my cube works perfectly with the code i already have (as long as there is only one sequence in the loop). i want to fully understand what i have before i start learning a new concept.

i simply need to know how to keep a function looping and then, after a fixed amount of time, loop a different function

i did try changing the way i defined time and it still does not work right

anatolyk69_gmail.c · November 21, 2011, 5:45pm

  time = millis();  // update your "time" regularly, not once

x=time-lasttime;  // you starting with lasttime = 0, and undefined "time"
                                    
if(x==3000)                  // why you expecting exact 3000 value?
                                     // try x > 3000                                        
  {
    seq=seq+1;
    lasttime=time;
   }

if (seq==1)
 {
   sequence1();
  }

if (seq=3)  // !!! you mean seq == 3 ?
  {
   sequence3();
   }

}

marzban123 · November 23, 2011, 4:50pm

thanks magician. that worked fine for me. i guess i just had the variables in the wrong places. how do you suggest i have the program continue to cycling through after it gets to the last sequence

anatolyk69_gmail.c · November 23, 2011, 5:48pm

Ok, it's easy:

if( x > 3000 )       // hope it's like in your sckech                               
  {
    seq=seq+1;
    lasttime=time;

if ( seq > 4 ) seq = 1;   // assuming that you have 4 sequences so far, change 4 to right number if  you have more than 4.
   }

system · December 7, 2011, 5:18am

marban: I stumbled on this topic trying to trouble shoot my 3x3 cube. I'm fairly new to coding and building circuits, however I seem to be approaching this project the same way you did. Right now I'm only testing one face of my cube (i.e. layers 1,2,3 and columns, 1,2,3 on a breadboard). I have everything connected in the same manner you do (other than I'm using different I/O pin assignments, but my connections are the same other wise) I'm using 3 ksp222a transistors to control the levels. The emitters are connected to ground, the base pins are each connected to 100ohm resistors and then to their respective I/O pins to control them and my collector pins are connected to the cathode layers I want to control.
The LED's I'm using have these specs:
5mm diameter
520 nm wavelength
3.2-3.8V Forward Voltage, at 20mA current
8000 mcd typical brightness
Viewing Angle : ±10 degrees
Maximum continuous current: 30mA
I've connected the LED columns to their respective I/O pins through 100Ohm resistors.

Here is the code I'm currently using:

#define C1 1
#define C2 2
#define C3 3
#define L1 11
#define L2 12
#define L3 13

void setup()
{
  pinMode(C1, OUTPUT);
  pinMode(C2, OUTPUT);
  pinMode(C3, OUTPUT);
  pinMode(L1, OUTPUT);
  pinMode(L2, OUTPUT);
  pinMode(L3, OUTPUT);
}
void loop()
{
digitalWrite(L1,HIGH);
  digitalWrite(L2,HIGH);
  digitalWrite(L3,HIGH);
  
  digitalWrite(C1,HIGH);
  digitalWrite(C2,LOW);
  digitalWrite(C3,LOW);
  
  delay(500);
  
  //all lvl 2
  digitalWrite(L1,HIGH);
  digitalWrite(L2,HIGH);
  digitalWrite(L3,HIGH);
  
  digitalWrite(C1,LOW);
  digitalWrite(C2,HIGH);
  digitalWrite(C3,LOW);
  
  delay(500);
  
  //all lvl 3
  digitalWrite(L1,HIGH);
  digitalWrite(L2,HIGH);
  digitalWrite(L3,HIGH);
  
  digitalWrite(C1,LOW);
  digitalWrite(C2,LOW);
  digitalWrite(C3,HIGH);
  
  delay(500);
  
}

(code tags added by moderator)
My assumption was that this would light up each column individually, and it does, however the C1 LED's barely light up and when I tried changing the I/O pin that conrtolled the C1 LED's they stayed on throughout the entire loop. I'm not quite sure what I'm doing wrong or if I've got a bad connection / part in the circuit. Any troubleshooting ideas would help at this point. Thanks!

CrossRoads · December 7, 2011, 6:17am

So you have basically this, but with only three columns wired up.

It would appear that you are driving what I show connected to D11-D19 with the L-names, and the transistors with the C names.

Otherwise you are turning on all layers at once, which kinda defeats the purpose of multiplexing. And stresses the Arduino output pin by driving 3 LEDs at the same time.

Or perhaps you are wired up some other way?

system · December 7, 2011, 7:32am

before anyone wastes their time responding to my comment. I finally discovered one of my output pins is broken so it works now...

system · May 5, 2021, 7:38pm