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### Topic: 4 digit seven-segment display ! (Read 3436 times)previous topic - next topic

#### Hilmar

##### Jan 19, 2013, 01:26 am
Hello, I am new to arduino, just got it a few days ago

So I have this 1 digit 7-segment display, I got it to work, displaying numbers and letters..

Now I want to use the 4 digit display, but it has 12 pins, and everything I find online is either 16 pins or 10 pins...

The following picture is a picture I took just now...

So I have 12 pins ...
I wish to know what pins to connect to the digital outputs, and what I connect to ground...
(Also, do I need 5v? Did not need for the 1 digit display.)

#### Osgeld

#1
##### Jan 19, 2013, 02:21 am
you might have to probe it out, its 7 segments, 1 dp and 4 commons

#### floresta

#2
##### Jan 19, 2013, 02:45 am
Quote
Now I want to use the 4 digit display, but it has 12 pins, and everything I find online is either 16 pins or 10 pins...

I did a quick search for led 4 digit and then clicked on two different displays that resembled yours.  Each came up with a link to a datasheet and both datasheets had the same pinout.

PIN          FUNCTION
1                E
2                D
3               DP
4                C
5                G
6     DIGIT 4 COMMON A/C
7                B
8     DIGIT 3 COMMON A/C
9     DIGIT 2 COMMON A/C
10                F
11                A
12     DIGIT 1 COMMON A/C

Don

#3
##### Jan 19, 2013, 03:32 am
You will need to multiplex the display. Drive the segments hi/lo as needed, then drive the common (anode or cathode) as needed to turn 1 digit on.
Earlier today there was a post that multiplexed by each segment. Little slower that was vs a whole digit at a time.
Whole digit needs a transistor to handle the common current from a digit. Single segment you can get by with just arduino pins.
Either case needs current limit resistor(s); 1 for each segment if driving the whole digit;1 per digit if multiplexing each individual segment.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### grendle

#4
##### Jan 23, 2013, 05:56 am
i have a display from lumex that looks identical to that, i use it with a max7219. let me know if you resolved your issue or not, i can share the code and send the data sheet, but like floresta said they're probably all the same pinout.

#### Docedison

#5
##### Jan 24, 2013, 06:02 am
The Max7219 would be an Ideal IC to use, easy, sketches available, libraries available and one 7219 can drive up to 8 digits and they can be cascaded, Too.

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

#6
##### Jan 24, 2013, 09:47 pm
Unless thats a common anode part, then the MAX7219 is not suitable.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### grendle

#7
##### Jan 25, 2013, 05:28 pm

Unless thats a common anode part, then the MAX7219 is not suitable.

common cathode

#8
##### Jan 25, 2013, 09:15 pm
There you go then, MAX7219 would be easy to use.
Connect segment pins to segments, connect 4 digit pins to the 4 common cathodes, and program away.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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