I am working on a timer project - specifically for timing pick-up basketball games (countdown from 12 mins). Too many arguments and we need to speed games up. Anyway, I needed a decent size display so I purchased an Equity alarm clock (model 30037) and took it apart. Now, I’m so new at this it isn’t funny but my head is spinning on all this anode/cathode/segment stuff.
Anyway, here is a pic of the display.
Using Arduino_Pin 10 (my black wire w/ 220 resistor) and Arduino_Pin 2 (my red wire), I can get each segment to light up if I touch the right combination
Arduino_Pin10 → LED_Pin1 (which is marked as A)
Arduino_Pin2 → LED_Pin21
Will light up the “:”
Arduino_Pin10 → LED_Pin3 (which is marked as B)
Arduino_Pin2 → LED_Pin10
Will light up the “left-upper” of Digit 2 (from the left)
When I mapped it all out (since I could not find a datasheet), I was able to determine which pins belong to which segment. (See attachment)
Now, based on the combinations, I have 24 combinations. LED_Pin3 and LED_Pin4 are common between.
My initial set of questions are:
- What kind of display is this? (I should note that when lighted, there appears to be 1 LED driving each segment.)
- Can I assume that LED_Pin3 (shown as B) and LED_Pin4 (shown as C) are my ground?
- Because of the 24 combinations, I’m assuming that I need to do multiplexing. If so, can I handle all of that within code or will it require something additional like shift registers? (This really goes back to question 1, because if I know what kind of display, I can research the “how” better)
Any help that you guys can provide would be very much appreciated. I’m new to this stuff (although I can handle a soldering iron and know how to program) and I have a lot to learn with Arduinio. Also, sorry for my “schematic” - just did what made sense. I’m sure it will make an electrical engineer cringe though!