There just has to be an easier way to go about this. I am very new to Arduino's and making circuits. I have most of my project working, but i want to know what is the best way to wire all these LEDs. I have so many wires here going into my MAX7219's and it's a huge rats nest. Should I not use wires at all and make solder traces all over the perfboard? If so, whats the best technique for that?
Just looking for suggestions. Yes i know this looks awful right now, but it works at the moment!
I was going to say use something like the 7219 but...... so I guess the real answer is to consider using a less archaic way to display information. An LCD panel could do the same job with four wires, so that gets pretty persuasive.
Bobsled:
I have so many wires here going into my MAX7219's and it's a huge rats nest.
How many 7219's are you using? A quick scan of the datasheet shows that two would suffice. I'd think seven segments x seven digits + seven segments x three digits would only be twenty-four wires. Looks like you've got a lot more.
Nick_Pyner:
I was going to say use something like the 7219 but...... so I guess the real answer is to consider using a less archaic way to display information. An LCD panel could do the same job with four wires, so that gets pretty persuasive.
This project that I'm working on is for someone else. They want these LED's specifically because we are making a custom hockey scoreboard for a board game. It's supposed to look lifelike when its done so we would like to stick with these LED's.
dougp:
How many 7219's are you using? A quick scan of the datasheet shows that two would suffice. I'd think seven segments x seven digits + seven segments x three digits would only be twenty-four wires. Looks like you've got a lot more.
I am using 2x 7219's. That should be all I need for this whole project. I haven't connected the last half of the LED's yet because its very tedious. And each of the single digit seven segments have 13 pins. 8 of them are for the segments (8 because of the DP), and the rest are the common cathodes (but you only need to use one of those). Then the 2 digit 7 segments on top have 18 pins each. So that's a current total of ~114 pins from the LED's that absolutely need connections.
cheche_romo:
You can try to etch your own PCB, you can use a heat transfer method with a laser printer and an iron
I thought about doing something like this. I'll look into that more. I have all the tools necessary to do this.
The other ideas are more elegant than mine, but, what about mounting the chips on the same board as the LED's? I have done that in the past, that makes the wires all short. I also put the wires in bundles with tie wraps so there is not the wild look, been doing the bundles thing for years
Last project was I think 27 LED's times two wires in a marine chart, put the wires in bundles and it did not look all that bad, should be a link I think to my web site in my name - look for the ATON display if you want - back maybe 10 posts or so
When I use perfboard I use lengths of solid copper wire on the front side of the board to make connections between the copper tracks. That makes for neat and simple on-board connections. But of course it does nothing for inter-board connections
Can you please post a copy of just how you connected the three digit display to the MAX7219 circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
You should be able to connect all the a segments together at the display board, same with b ,c ,d, e, f, g and dp.
So for a 3 digit display you should have 8 wires (segment) + 3 wires (commons anode or cathode) = 11 wires
Rather than bring every wire back to the 7219's - why not wire the busses locally...
All the a-segment together, the b-segment etc all the way through to all the dp’s.
Then you'd be looking at 2x 7219 = 2x 16 wires from the display controller to the LED panel. 8x segments and 8x commons.
As noted above in #2 (and allowing for 16x 8-segment displays incl dp).
Looking at the picture again, and noting that there are actually only 10 LED characters, I just can't see how you can possibly have all that wire with two 7219s. OK, so the LED display I have has only 4 characters plus decimal points with one 7219, but I'm sure it only has twelve wires. With the mess like you have, and you say not all the LEDs are connected?, I can only assume that something else is going on that you're not telling us about.
lastchancename:
Rather than bring every wire back to the 7219's - why not wire the busses locally...
All the a-segment together, the b-segment etc all the way through to all the dp’s.
Then you'd be looking at 2x 7219 = 2x 16 wires from the display controller to the LED panel. 8x segments and 8x commons.
As noted above in #2 (and allowing for 16x 8-segment displays incl dp).
(EDIT - Tom George beat me to it!)
This would probably work best for me. I didn't even think about this solution haha. Thanks.
For everyone that asked, here are the links to the datasheets of the LEDs:
Too late now, I suspect, but an alternative to the two max chips would be a single ht16k33 module. These can drive up to 16 digits. They use the i2c bus, so with the module soldered only the display PCB, only 4 wires would go back to the Uno.