I have a 4-Digit, 8-Segment LED numeric display. Basically, a digital clock face with decimals after each digit for some strange reason. It has 12 pins. I have been unable to track down a wiring diagram for it (part number 5461AS included in this Mega 2560 R3 Starter Kit | SainSmart – SainSmart.com kit. The kit came with downloadable tutorials, which includes wiring diagrams for a few different models of 4-digit displays, but does not include the display that comes with the kit. The wiring diagrams they provide are also typically flawed in some way, and their code is strewn with errors, so I've lost faith in their ability to help me. Any ideas on how to figure out how to wire this display?
EDIT: I found a close approximation of the display, and the diagram matched. Now my concern is that a few of the leds appear to have blown when I was trying to test earlier. Whoops...
Hassurunous:
Now my concern is that a few of the leds appear to have blown when I was trying to test earlier. Whoops...
Testing can be done non-destructively with most ohmmeters set to a Low-ohms setting or using the diode check function.
Also, a 5V supply and a 2K resistor will do just as well.
The segments will light faintly.
Just make a map of the pins and poke around looking for something to light and note that, process of elimination.
Also, it may be that not every segment lights on each digit, even though it may look that way.
I did finally get it wired up correctly, I think, as everything but 4 LEDs, which I'm assuming I burnt out, lit up extremely bright. I then found out that I should be using a resistor on each cathode, so I unplugged everything ASAP, hooked up some 220 resistors, and tested each cathode. All of them light up except the cathode on pin 9, which is the second digit on the display. Without a resistor, it lights up fine, with a resistor, even one that works just fine on the other 3 cathodes, it refuses to light up. Any ideas what's going on there? Did I burn more out than I thought?
If by that you mean that none of the segments in a particular digit light it could be that they're not wired up.
Sometimes it looks like a 4 digit display, but they were manufactured for a purpose other than what you expect.
I have some with a colon between each digit, but only one actually works.
I don't know what your source was when you were "testing" previously. If it was a supply with some muscle in it and you just laid the output to your LEDs then they may have met an untimely end.
Okay, I got everything wired up to separate pins on the arduino Mega 2560, as I discovered it could not support the load of that many LEDs on a single ground (I know, I know, rookie mistake). Now what I'm noticing is even weirder. When I hook up everything except the second digit I get this:
Basically, when the second digit is plugged in, all of the middle segments turn off and the second digit still does not come on. Would I be better off just grabbing a new LED display? Is this related somehow to the fact that the bottom segments of the second and third digit, as well as the middle segment of the second digit do not light up no matter what I do?
