8 by 7 LED Matrix (easy)

By Miguel Nonaka, Andre Nonaka and Julius PeBenito

Step 1: Materials Needed

The first thing you need to do is to buy the following equipment, it should cost you less than 40$ (which it was for me at my local tech shop):

1. 56 LEDs (I use white LEDS, but any colours will be fine)
2. 15 to 40 wires (male to male)
3. 15 wires (male to female)
4. Arduino Board (does not have to be specific, just ones that work, I used an Arduino Uno board)
5. Breadboard (the one you don't need solder the components)
6. Resistors (330ohms)
7. Soldering gun
8. Solder (I use lead solder, but you can use non-lead one)
9. Cardboard (for making the holes on which to put the LED on for soldering)

Step 2: Making the Holes on the Cardboard and Putting the LEDs in It.

The first step that needs to be made, before starting the soldering, is making the holes in cardboard (there needs to be 7 rows and 8 columns). Furthermore, it can be any type cardboard as long as its width is wide enough to hold the bulb of an LED.

So lets start, with drawing the lines on the cardboard (I painted my cardboard, before starting drawing the lines, just for decoration purposes). The lines of rows and column that you are making with your ruler and pencil need to be straight and drawn in the cardboard. Place dots in the rows and column you drew (needs to be 7 dots per row and 8 dots per column. Make the dots, that you drew to represent holes, at least half a centimeter apart (ours was one centimeter apart, which more difficult to solder). Once you are done drawing the dots, columns and rows, take a pen with a sharp tip and punch a hole through the place where you drew a dot, do that for each one of the dots that you drew in the rows and columns. Then, after your done making the holes, place the 56 LED, as shown above, in the holes. Once you are done all of this, the cardboard with LEDs will be use a support stand, when you start soldering the leads together (anode with anode (longer ones) and cathode with cathode (shorter ones)).

Step 3: Soldering the Wires and LEDs

Now comes the soldering of the leads of an LED. There is, first of all, two leads; one called an anode (the longer one, which is positive) and one that is called cathode (the shorter one, which is negative). As seen, in the pictures above, you will need to solder the cathode going straight from left to right as the rows, while soldering the anodes going above them as the columns. Moreover, you will need to be careful not to connect the leads together (anode and cathode), keep them operated by soldering all the cathodes first and then the anode. You will to use a pencil to make the anode go up and to create the separation between cathode and anode leads. Once you are done, you will need to solder the wires on the cathodes and anodes that are at both extremes, as shown above. You will need to have 15 male to male wires (the ones I used came from an disassembled computer) to solder them on the exposed column and the rows (exposed leads). These wires, once soldered, will carried the power from the breadboard to the matrix.

Step 4: Preparing the Breadboard Connections and Connecting the Matrix to It.

Now, that we are done the wiring and LED soldering for the matrix, we will need to start preparing the connections of the breadboard to the Arduino UNO, as shown above. All the anode wires (column wires) will need to go the part of the connection (breadboard connection) that doesn't have resistors, as shown above. The cathodes wires, will need to go the part of the connection (breadboard connection) that has resistors. Make sure all the wires that are connected to the breadboard are connected in the right pins, in the Arduino, as shown above. Once you are done, you will start coding to make the matrix work.

Step 5: The Code

Here is the code that we used for our LED matrix (7 by 8). This file is in .txt format, however you can just copy and paste the code into the Arduino IDE and it should work just fine. Furthermore, if you want to edit the already default phrase, in the code, just change the 1 and 0 that are underneath the "const charMapType charBlank" for example.

Step 6: Videos About Our Projects and References

Our project and our code is a revised version from:

https://www.circuitspecialists.com/blog/build-8x8-led-matrix/

Step 7: The Code in .ino Format (for Arduino - Just in Case)