Here Are Many Ways To Build DIY LED Dot Matrix Display For Arduino Scrolling Text and Other Effects. Save Money By Buying Raw Components. There are hundreds of online websites and online shops who will sell you 8×8 dot matrix display at $10.00. But, basically if you build for yourself you can decrease the cost plus make it bigger, smaller, custom shaped etc.
DIY LED Dot Matrix Display For Arduino : Basics
For 3×3 matrix, that is same colored 9 LEDs, practically you need – Arduino board, 9 LEDs, few jumper wires and one breadboard.
For 10×8 matrix, that is same colored 80 LEDs, you will need – Arduino board, 80 LEDs, few jumper wires, 10 2N3904 transistors, 4017 IC ( these are quite commonly used, you can read our motor control guide for some basics ), 10 220 Ohm resisters and one breadboard.
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For building 8×8 matrix which looks like ready made dot matrix display, you will need – Arduino board and a kit usually which cost less than 1.50 USD.
The dot matrix display depends on theory of multiplexing. It is a way to split the information into fragments and send it one by one. 10 pieces builds 10 rows – this is minimum for the IC 4017.
All the columns are positives of the LEDs and the rows are negatives. So if the first row is connected to ground and we send signal to the first column, it will only light the first LED in the row.
To get a good display we need to scan the rows very fast, so fast the the human eye thinks that all of the rows are connected at the same time. IC 4017 also named as 4017 decade counter, it helps us with the multiplexing. It scans the rows of the matrix and lights row in a controlled manner. A transistor with a resistor is needed to ground.
For “SURGEON ON EMERGENCY”, “NEWLY MARRIED SURGEONS” (lol) like bigger texts, LED lights are better, else buy the kit, simply join and do the works.
DIY LED Dot Matrix Display For Arduino Scrolling Text : 9 LEDs
This code is for lighting up four corner LEDs and middle LED :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | // anodes int row[] = {5,6,7}; // cathodes int col[] = {8,9,10}; void setup() { for (int i=0;i<3;i++) { pinMode(row[i], OUTPUT); pinMode(col[i], OUTPUT); } allOff(); } void loop() { digitalWrite(row[1], HIGH); digitalWrite(col[1], LOW); } void allOff() { for (int i=0;i<3;i++) { digitalWrite(row[i], LOW); digitalWrite(col[i], HIGH); } } |
Pattern can be achieved with this code :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | // anodes int row[] = {5,6,7}; // cathodes int col[] = {8,9,10}; // bit patterns for each row byte data[] = { 0,0,0}; // defines the size of the matrix int columns = 3; int rows = 3; //millisecond delay between displaying each row int pause = 1; void setup() { for (int i=0;i<3;i++) { pinMode(row[i], OUTPUT); pinMode(col[i], OUTPUT); } allOff(); } void loop() { // define pattern data[0] = B00000101; data[1] = B00000010; data[2] = B00000101; showPattern(); } void allOff() { for (int i=0;i<3;i++) { digitalWrite(row[i], LOW); digitalWrite(col[i], HIGH); } } void showPattern() { for (int thisrow=0;thisrow<rows;thisrow++) { //turn everything off allOff(); //turn on current row digitalWrite(row[thisrow], HIGH); // loop through columns of this row and light for (int thiscol=0;thiscol<columns;thiscol++) { if (bitRead(data[thisrow],columns-thiscol-1)==1) { digitalWrite(col[thiscol], LOW); } else { digitalWrite(col[thiscol], HIGH); } } delay(pause); } } |
Circuit diagram and coding provided by multiwingspan.co.uk, very good idea; but it has limitations. LEDs are not microscopic objects! Basically it is too basic. However, the importance is in wiring.
Circuit diagram is included in infographics.
DIY LED Dot Matrix Display For Arduino Scrolling Text : 80 LEDs
In this case you will need the components. Coding and circuit diagram is by Sohil Patel (sohilpatel.org). This is the most practical and basic of dot matrix display. You will everything o GitHub :
1 | https://github.com/sohil4932/10x8_LED_Matrix |
Smart guy. Pushing to Github decreases our typing & copy-paste.
Circuit diagram is included in infographics.
DIY LED Dot Matrix Display For Arduino Scrolling Text : Our Method
But, we dislike to work so much, also do not want to make the lady of Adafruit more richer! Best solution is buying the kits which after the work looks exactly like ready to use product. You will get in Amazon, Ebay etc. websites. Huge number of sellers, quite competitive market, a bit research will give the cheapest possible rate.
If you search with MAX7219 on Google web search, you will see lot competition. That MAX7219 is the driver. The prices are so less that we can not say “China has made the pricing great, but it (a $10 item) should cost $1.00”. Shipping cost is more than product’s value! Kit and assembled are competing in price, probably buying according to your choice is better. Smaller can also show scrolling. You will get codes on Arduino Playground.
Now if you need color changing display, pay $12.00. Colorduino is the name. When White, Red, Blue, Green, Yellow becomes available and many pieces are joined, it becomes a zoomed form of our normal displays. Basic is same.
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