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  • Author Author: idanre1
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Seven segment and arduino

idanre1

I have bought a 4 digit seven segment module on banggood.

1 Pcs 0.561 Pcs 7-Segment 4 Digit Super Red LED Display Common Anode Time - US$1.79

these things cost about 2$ and i wanted to test if they worth anything.

image

 

I have decided to connect them to arduino nano in a quick plug and play connection, so that it can be added for existing design using only 1 connector.

 

The thing about buying from china online is that you not always get what you order.

The module I received is CL5642BH and the module they published is HSX41056K.

So without any schematics i have decided to reverse engineering it using a breadboard.

 

Apparently the module turned out to be common anode as specified and with pin diagram as in arduino mega - How to wire up 4-digit 7-segment display? - Arduino Stack Exchange

 

When you google about these displays there is allot on confusion when to put the current limiting resistors, some say in the digits, some in the segments.

Actually I figured it out it can be both ways, only the code of the arduino is changed.

 

Then I found a nice library to deal with with that really simplifying it all

http://playground.arduino.cc/Main/SevenSegmentLibrary

 

You can config where you want to put the resistors and if its common anode/cathode or even more complex drivers and it works!

Just by reading the code you can see this lib is great.

 

Form factor:

As I mentioned i have decided to make the circuit as compact as possible.

Because of that I put the resistors on the digits (4 instead of 8 resistors) and I used perforated board.

 

The front side is quite neat, only display and 4 resistors (and connectors)

image

 

The rear side is quite messy


image

 

I was using an old IDE connector from an old computer to drive it all from the arduino


image

 

 

Open items:

  • The SevSeg library uses loop to always update the leds (kind of a tdma over the leds), I read around there is a was to use charlieplexing for keeping the leds on without the fluctuations.
    Still I didnt find any way to implement it on my display.
    Anyone have an idea?
  • Decreasing cable amount. Is there a module that uses i2c to only take 2 cables out of the arduino onstead of 12 cables?

 

Video of operation:

 

Idan

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