My project involves a TON of digital pins being used. It's split into two pieces. The first being a stationary box, with an arduino inside that does all of the logic. The second is a separable "faceplate" that's really just a simple circuit. I'd like to be able to just plug it in like I would with anything else, but plugging in EACH wire to the right place, and without the chance of disconnect would take too long, especially considering this is designed to be swapped out often.
I've looked into 18/20 pin connectors. I only need 17, so 18/20 are probably the most cost efficient way of doing it. 16 for output, 1 for ground.
I've looked into various connectors. On Reddit I was recommended to use Raster, JST, or Ribbon Cables. I have no clue about the strengths or advantages of each though. As far as I can tell, Raster is the best for general usability: simple to use, and isn't too hard on the eyes. Ribbon Cables seem to break often from what I hear, so I'd rather not use those unless that can be disproved.
I'd like the female port to be able to be depressed, similar to a phone's charging port. The male port is stationary, as the positioning is the same on every variant of the second piece.
I'm inexperienced with Soldering, although I can practice a bit. Anything to get this working the way I'd like. I'm willing to share more details of my project, although the less the better. As for a question you might ask: why? The second piece isn't really anything complicated. It's just meant to be wired in a way that would allow you to add, or remove unnecessary pieces, and in a configuration fit by the user. I can't use a port like USB, as I'm trying to avoid unnecessary complications. It's just an "on/off" switch for each individual wire.
I see two different scenarios.
1). Both equipments are powered down at the time of being connected.
2) One or both are powered up.
This calls for very different connectors. For case 1) almost any connector would do but knowledge about static electricity is needed.
For case 2) You need special connectors made for "hot swap". Then the ground must connect first and later the signals. All due to the risc of static electricity, different potentials between the 2 parts.
Railroader:
I see two different scenarios.
1). Both equipments are powered down at the time of being connected.
2) One or both are powered up.
This calls for very different connectors. For case 1) almost any connector would do but knowledge about static electricity is needed.
For case 2) You need special connectors made for "hot swap". Then the ground must connect first and later the signals. All due to the risc of static electricity, different potentials between the 2 parts.
See, the board isn't really "powered" as it has zero logic. It could just be reduced to a couple of LEDs. I didn't think about having the ground connect first though. Since they would be connected together, the second piece draws power from the first, meaning that if the first is off, or the second is disconnected, then the second will be "off."
Realistically, it could be as simple as cutting down the pins on the male connector a short bit, and leaving the ground pin long, right? Or would a "rising piece" be better? I guess I could also just use a second one pin connector that extends out a bit. I still have the issue of knowing what one to use.
If a passive load is connected to a powered device the riscs are slim. The most sencitive pins are inputs but even output pins can get damaged by static or overvoltage.
Drop the thought of modifying connectors. That's most often impossible in reality.
Special care is needed but clouds of protecting components would make it difficult. What causion, what protection You need is not easy to say from Your question.
How often is this going to be unplugged and plugged?
What mechanical movement between the two, which must flex the cable?
Does it really have to be 17 wires or can you put a shift register/LED driver on the sub board?
How many of these will you make?
If there will be only 1 or 2 of these then IDC connectors on ribbon cable will be easiest. IDC stands for Insulation Displacement Connector. You don't need to strip any wires: it clamps onto the cable and little teeth bite through the insulation. It must be crimped straight: use a woodworking bench vise to clamp it shut. The PCB side connector has a 0.1" pitch so it is not too small to solder easily.
MorganS:
How often is this going to be unplugged and plugged?
What mechanical movement between the two, which must flex the cable?
Does it really have to be 17 wires or can you put a shift register/LED driver on the sub board?
How many of these will you make?
If there will be only 1 or 2 of these then IDC connectors on ribbon cable will be easiest. IDC stands for Insulation Displacement Connector. You don't need to strip any wires: it clamps onto the cable and little teeth bite through the insulation. It must be crimped straight: use a woodworking bench vise to clamp it shut. The PCB side connector has a 0.1" pitch so it is not too small to solder easily.
I have no clue. The first piece is designed to have one male port, and then as many female ports as you want the number of second pieces. As for how many times? Genuinely, any amount. It just needs to be durable. If I had to guess? Over the course of a year, it could be anywhere from 5 to 500.
I could probably use a Shift Register / Multiplexer / LED Driver, but I'm trying to keep it as low cost as possible when using my components that I currently own. The Uno has just enough pins for me to use, so I have no need for using any sort of expander or driver. It looks like the IDC connector is what I'm looking for. For now I just need two connectors.
On the other note, I talked to someone who works as an engineer for a local company, he claims that the ribbon cables are a bad idea, claims that they break too often and aren't reliable, although they do work with military grade stuff...
500 times a year is more than once a day. That is pretty harsh service for a connector. It will be difficult to find a connector which will last more than a couple of years of that. Maybe some military connectors can do it.
DB25 would be my next recommendation. The solder-cup versions are cheap, if a little fiddly to build up. It will fail at the solder joint unless you are very good with the strain releif. The crimp versions will probably last for the lifetime you need but the good crimper tool costs about $600
Why solder DB25 plugs when you can buy ready-made cables? Just cut off the part you don't need. Get a male/male cable, cut it in half, and you have two "faceplate" connections. Probably doesn't get much sturdier than that.
Proper strain relief on the "faceplate" component, and connect the wires as needed on that side.
Honestly I feel like the DB25 Solder Connector looks like the best option for me currently. I think WVMarle's option seems... Hacky, sorry for the pun. I'm not sure it would look very pretty in my opinion.
wvmarle:
Why hacky? More like a way to save yourself half the soldering work. At least the connector would look good, for sure.
The way I've read it, you're saying to connect a male connector to the pins on one end, and then leave them hanging out. I don't think that looks very elegant. An actual port would probably be a lot better.
If I chose to use the DB25, I could solder once for the initial piece, and then once more for each face plate. I don't think it would be THAT much work. And it would look pretty good to anyone who would be using it. Wires hanging out wouldn't be very pretty IMO. It isn't meant for electricians, or me necessarily. Plus, a port you can't plug in wrong would be helpful.
Female port where it belongs, normal port. Looking good.
Male connector you get as complete wire; cut off the other half; connect the wire bundle to your switches or LEDs or whatever. So now you have properly molded connector on regular cable connecting to your project.