arduino 7 segment library

So today, I’m going to show you how to connect the four of a either a four digit Ali. Seven segment LED display. That is one difficult name to say or if you want, if you have just four single ones like the ones back here, how to connect. Four of these to become just like one of these, so you can work with four digits instead and how you write code for that. So in this episode, I’m going to show you how to just connect them directly like we did in episode 7 with one digit and in the next episode. I’Ll show you how to do this with the 595 once again, just using three pins to do all this, but let’s just dive right in and show you how to hook it up. First let’s try to explain the difference in the pin out. So this goes from this here is: pin 1 to 6 and then 7 to 12 that’s how the pins goes now. This line here was a and then down the side b, c d, e, f g, so you will find that a on pin 11 a and B is some pin. 7 C is some pin. 4 4 D is on. Pin 2 e is on pin 1 change. Color e on pin 1 F on pin 10 key on, pin I’ve. If we want the decimal, it is pin 3 dot. Let’S just add the numbers for the for the different segments.

Now, when we have these here, let’s also add the pins for the one segment display. Now here is the big difference on the on the four digit display. We have four grounds, sorry, that is the wrong word, the the common pin. So we have one common pin for each digit, so this is common one. So this is for this. We call this one and then we have on pin 9 common to right. We should write this as pin 12 and this is pin 9 comma 2. So this is for this segment common 3, something 8 and on pin 6 is common for now. What this means is that when you light up the ABCD efg and C 1 – and you connect them with either if it’s common, a no two common cathode, but you connect ground or voltage to see one. You will light up this digit C 2. You will light up this C 3. This cut right. This is 3, this is 4, so you have the different ones and then you will multiplex between the four common pins and that way you will light up the 4 LEDs. So what you can do you can take the four one digit segments over here and you will. You would actually just connect all the ace to a like this, a eh eh and then the same with B’s and C’s and all the way around and then instead, you would take this one as c1, this ground pin sc2 this ground, pin a c3 and this Ground pin SC for that ground, again sorry, common pin and if you count this up so here we have 12 pins, and here we have 1, 2, 3, 4, 5, 6, 7, 8 and then five common pin out for common pins.

So 9, 10. 11. 12. So this is what this looks like inside, so nothing more strange about it than that. So now, let’s just work with this one and hook it up to the Arduino. To connect this. We are going to need 12 DuPont cables and I put it on a breadboard to get better connection for the cables. I also made a small cheat sheet here, so we’re going to put a connect, pin 2 on the Arduino to segment a and this is switch. Pin on the LED segment it is so pin. 2 is going to go to pin 11 Arduino, pin three to pin seven for to pin 405 to pin to Arduino, pin five to pin to from this one. I remember you start in the lower left corner from one up to six, and then you continue on the upper right corner, going from seven to 12, so pin 6 to pin 1 right and then pin 7 arduino to pin 10 and finally of those pins pin. 8 on the arduino to pin 5 ok, so we have all the segment pins connected, and now we have four should have four more pins here, which are for the common pins for each digit. So common pin 1 is on number 12, so we are going to continue and put that on. Pin 9 on the arduino and pin 9 on the LED. Second, display is c2 put on pen ten on the arduino and pin eight on the LED segment to pin 11 on the arduino.

This is a common pin, 3 for the third segment and finally pin six there to pin 12 on the Arduino taking up a lot of pins on the Arduino, but it is now hooked up as it should be, and now we can start writing the code. So, to give us a head start, we are going to use the same code that we ended up doing in anything, Arduino Episode, seven, where we use where we worked with a one. Digit seven segment LED display so and we work with the common, a node. So in that sketch we also added all the pins, a through G 2 2 to 8. So this is the same setup of the a through G pins as in the one digit example. So if you really want to know how to set up a or code to write and numbers to a seven segment LED display, then you should watch episode. 7. First before you watch this here we are just going to alter this code to a four digit. Seven segment LED display geez one name. So what we’re going to do just to show you that it is very similar we are going to add the digit 1 pin, which was pin 9. We are also going to get this pin mode on digit, 1. 2. Outputs. Now, because this is a common anode, we are going to to get a 0 done. We need the common pin to be high.

I know this because a0 is all the numbers lit, except the middle one pin G, which is so then d1 digital right, d1 should also be high. Now let’s see what happens when we upload this. So now we have one of the four sec digits counting from zero to nine. So what we just did was make this I and that happen okay. So now we need to add the four other, the three other digits once again, just to show you oops sorry about that was a bit too fast. Just to show you what this does so now we have all four digit pins high and, as you might expect, all four digits are now counting from zero to nine. Now this isn’t a very practical thing, because you want the four digits to show different things, and now this is where we begin to have to multiplex and that’s. How I’m going to show you how to do now. So let’s start by doing only digit one showing now I’m going to write a zero on digit 1, a 1 on DD 2 and 0 1, 2, 3 that’s. What I’m going to write on the four digits? So we begin with the first digit and write a 0 now we’re going to need a short delay: let’s try, 10 milliseconds and then we’re going to write a 1, and we are going to write that on 10 2. So we make dg2 high and the others low again 10 milliseconds.

That might be too much I’ll. Try that out. We need a bit of delay, or else it will just be a blur so that really isn’t working, but just a few milliseconds will work. So we wrote the one there and then we’ll write a two two digit three now remember. We can only write to one digit at a time. That’S that’s the trick here and the final digit number four should have a three on it and the rest. We are going to comment out don’t that right so let’s upload this again now we have it writing. 0. 1. 2. 3, but with a lot of flickering so 10 was a bit too much let’s, just pull it down to 1 millisecond see if that is too much or too little they’re now not very much flickering, at least so. I can see it, and – and this is how you do it – zero one, two, three bye. Of course, you can’t just write these numbers all the time, but this is the method, so you write one number and then you change the digit and you write the next one and so on and so forth. So this is the basic of basics, of working with a four digit. Seven segment LED display, and this is how easy it is to work with four digits instead of just one. So hopefully you have gotten something out of this really rudimentary explanation, but it’s just to try to teach you how to work with forward with this four digit LED display or just four single ones.

So I hope you like this. If you do press the like button subscribe, if you haven’t already and in the next episode, we are going to do the same thing, but with a 595 so using only three pins again, we are going to write four numbers using three pins on the Arduino. So the 595, a really versatile chip that you can do a lot of fun stuff with so hope.


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Comment (28)

  1. Hi, im trying to finish my project but im having trouble in my codes. How can i make the zero remain in the 1st tube after looping and so o , until it goes back to the first one and loop again? Thank you

  2. My display is not doing anything. I’ve dissemble it several times. Code is compiling fine. There is no power going to the display at all.

    1. Have you tried inverting polarity? So connect the common pin to ground OR v+ depending on what you have it connected to at the moment?

    2. @Kristian Blåsol Thanks Kristian. Once i reversed the polarity and just focused, it worked. I have it moving from digit to digit as it counts. Nothing major, but its progress.

  3. Where are your current-limiting resistors? Why are you connecting this display directly to Arduino outputs without resistors?

  4. The code on your site is corrupt but I was able to figure out what is going on based on your training! You do man!

  5. Very well explained and simple to understand. This is my first working project with arduino. I am also going to repurpose it into a small digital clock. Thank you for the great tutorial.


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