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Core Electronics Forum

Dual 7-Segment Display - LED (RGB)

#1

How do I wire this up as the datasheet doesn’t mention the pin out (relative to the package) & there is no implied ground or power pins.

I’m planning on using an Arduino & 74HC595 shift register to set the segments & only require the ability to set all the segments to the same colour. I need to be able to set the RGB colour value dynamically. It woud be helpfull if you could point me at any projects using this product.

#2

I already know about using 74HC595 to light up the segments & I’ve gotten these working with 4 separate red 7 segment common cathode displays with the following circuit.

I have the following issues which need clarification.

  1. My issues are the pin outs as these aren’t documented. Is it similar to a normal 7 segment led? Obviously it will 1-7 at the bottom & 8 to 14 on top.
  2. Can you please confirm if this product is common cathode as I’m wanting to use the anode to change the brightness?
  3. I think I can use separate WS8211 chips to handle the RGB lines for each segment. Is there an issues with only a single resister value for each RGB line? Red needs to be limited to 2.0-2.4V, Green to 2.85-3.4V & Blue to 2.95-3.4V. For my circuit I’m using a separate resistor for each segment so the segments are the same brightness.
  4. Are there any projects or circuits created using this product. I have been unable to find anything.
#3

typically common cathode is preferred…or mostly used…if the negative rail is going to the cathodes i think…that is more common…

#4

The datasheet on the SparkFun website most definitely shows the pinouts of the display. You don’t need a +ve and -ve pin as the control circuitry sets the voltage on each individual colour segment.

If you think of this display as a red display, a blue display, and a green display then you can set up one of them using your circuitry. When you have say the red working, you duplicate the circuitry and code for the green and blue. Then add code to handle what mix of RGB you want.

Here’s a link to the SparkFun page. Read the comments at the end.

#6

Thank you for your answer.

Yes both datasheets mentions the pinout & their purpose. Which I now understand & am pretty sure it’s common cathode.

The pinout isn’t documented relative to the package. It mentions each pin & what it does. A standard 7 segment display has pins 1 - 5 at the bottom if you’re facing the front of the segment & go from 5 - 10 at the top in an anti-clockwise orientation. Is this package the same? If it’s not, then what is the pinout relative to the package?

The url shows what I mean https://components101.com/sites/default/files/component_pin/7-segment-display-pin-diagr_0.png

It’s a 7 dollar part & if I apply voltage to the wrong pins then I’m going to destroy the part or the segment.

#7

have you tried contacting sparkfun for a more detailed breakdown of the specific connections on the display…???

#8

I did get conformation that these are common cathode & am also trying Sparkfun’s support.I’ll return any useful information that I obtain.

Thankyou to all that replied!

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