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### Topic: Question about datasheet and 7 segment display (Read 3725 times)previous topic - next topic

#### Summerman

##### Aug 02, 2011, 05:08 am
I'm trying to get used to reading data sheets. I have a 7 segment single digit display (Ledtech LC 8031-11). Are the segments usually labeled clockwise from the top ABCDEF with G being the middle horizontal segment? I'm not seeing anything on the data sheet that tells me anything.

A
--
F  |   |  B
--
E  |   |  C
--
D

#### Techone

#1
##### Aug 02, 2011, 05:16 am
Quote
I'm trying to get used to reading data sheets. I have a 7 segment single digit display (Ledtech LC 8031-11). Are the segments usually labeled clockwise from the top ABCDEF with G being the middle horizontal segment?

Correct.

The datasheet alway assume you know what is a , b , c  ...   The datasheet will tell yopu what pin is for which segments and it is a coomun anode or a commun cathode. And also the current and voltage of the segments. example : 1.8 V @ 10mA. And DONT forget the limiting resistors !!!

#### Summerman

#2
##### Aug 02, 2011, 05:36 am
I'm going to assume that I will need a resistor for each segment. Correct?

#3
##### Aug 02, 2011, 07:38 am
Yes. a resister per 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.

#### Techone

#4
##### Aug 02, 2011, 05:54 pm
Quote
I have a 7 segment single digit display (Ledtech LC 8031-11).

I try to locate on the web the datasheet with no sucess.  This display is a CA <-- Commun Anode  or CC <-- Commun Cathode
If CA, the CA goes to +5, if CC the CC goes to GND. To display them using the code digitalWrite( pin, LOW or HIGH ) is : use LOW with CA, or use HIGH with CC.

#5
##### Aug 03, 2011, 01:52 am
I imagine you will find the part is very similar to 8041-11, different color perhaps.
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.

#6
##### Aug 03, 2011, 01:58 am
Here you go, ledtech website a little difficult to follow
http://www.ledtech.com.tw/newweb/newweb/img/images_product/LA(C)8031-11B%20EWRN.pdf
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.

#### johnwasser

#7
##### Aug 03, 2011, 02:13 am

I have a 7 segment single digit display (Ledtech LC 8031-11)

That model number is for a 17-segment alphanumeric display, not 7-segment.

The datasheet shows the face of the display and what each of the 17 segments are called.  Then it shows which pin goes to each segment.
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#### Techone

#8
##### Aug 03, 2011, 03:45 am

I will use those sites for futures use. Thanks.

@johnwasser

I notice the LC is a CC - Commun Cathode Alphanumeric display. So how can we help the PO Summerman ?  I guess he is wondering how to connect the display. 17 pins... usage of shift registers.

#### Summerman

#9
##### Aug 05, 2011, 03:35 amLast Edit: Aug 05, 2011, 03:43 am by Summerman Reason: 1
I finally got it figured out and have it up and running. The Data sheet I pulled off the web is for a Ledtech single digit display with four models. I found a couple of different data sheets that had this one listed and the easiest one to use is a single page. There are several models on the page and the one I used to get what I needed was for the LC80X1-11 which I figured was the one I have. It took me a couple of nights putting the circuit together and taking it apart several times to finally get it figured out and working. This has given me some good learning on how use data sheets.

Another question I have is concerning the difference between a common cathode (LC80X1-11) and the common anode (LA80X1-11) type. I have a grab bag of these single digit displays of both types. I tried hooking one of the common anode types up but it isn't working. There must be a different way to hook those up than the common cathode types.

Thanks everyone for the input to this discussion. I sure appreciate the help.

#### johnwasser

#10
##### Aug 05, 2011, 03:43 am

Another question I have is concerning the difference between a common cathode (LC80X1-11) and the common anode (LA80X1-11) type. I have a grab bag of these single digit displays of both types. I tried hooking one of the common anode types up but it isn't working. There must be a different way to hook those up than the common cathode types.

The difference is the direction the current flows through the LEDs.  Each segment still connects through a resistor to a data pin.  The Common is either tied to Ground (Common Cathode) and the segment lights when the output pin is HIGH or connected to +5 (Common Anode) and the segment lights when the output pin is LOW.
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#11
##### Aug 05, 2011, 03:52 am
This should answer your anode/cathode question. The logic part can be the arduino output, a shift register, etc.
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.

#### Summerman

#12
##### Aug 05, 2011, 04:01 am
Thanks. That works. I just need to play around with circuit and sketch to make sure I understand what is going on. Thanks for that explanation.

#### Summerman

#13
##### Aug 05, 2011, 04:29 am

Thanks for the diagram.

Is that a shift register in the diagram?

#14
##### Aug 05, 2011, 04:54 am
Yes, just happened to be on the diagram I started from.