Inspired by the proffieboard test rig and the flip down connectors used with ribbon cables, I started wondering about the possibility of connecting a proffieboard to a saber using some kind of clamping connection on the edges of the board, rather than soldering it in place. The main excuse to do so would be for the proffieboard to be easier to remove from a chassis (and therefore swappable between chassis), as well as for cable management purposes (through hole joints annoy me). So do you guys know of any such connector? Maybe something like a laptop memory connector? Would pogo pins work if there was a clamping mechanism over top of them?
While this might be possible, I’m not sure if it’s going to work.
The amount of power that goes through the BATT+ and LED1-6 connectors will make it difficult to find a suitable connector I think.
Please let us know if you find something that will work though. Solderless installation would be attractive to lots of people I think… I myself have dreamt of using 1mm screws for this very purpose.
browsing through mouser, a couple ideas are beginning to seem feasible:
card edge connectors like are used with laptop ram or m.2 drives. would require revision to the proffieboard pcb to accomodate.
card edge connectors like are used for pcie cards, where it’s just a straight push in. Again, needs modified proffieboard.
solder short pogo pins to profieboard contact pads. May or may not need larger holes. Maybe this?
I think if we can find a spring loaded contact that would work, a clamping mechanism could be 3d printed without too much difficulty. The current is the hard part. What’s the max current through any pin likely to be, say for a 4 strip zigzag blade and a 4w speaker?
Round pin header/sockets might work.
These are rated for 3A:
Not sure if there is something available with a higher current rating…
Using both BATT- connectors, and join two FETs together, and it might be enough…
Not actually solder free of course, but removable and it would form a secure connection. Unlike pogo-pins it wouldn’t need something to hold the board in place.
M.2 connectors are rated for 0.5A each, but there are upto 55 in a 16.5mm connector. If we leave 13 pins for “other”, you could potentially pass about 10.5A. Would that be enough? They are rated for just 60 cycles, though.
Might be an option for the (funny coincidence) M2 board.
I guess my big question is how much current the proffieboard really needs to handle. If we were to use the external FET trick for all the outputs, could we get away with very low current from the actual proffieboard? I only ask because I’m very unfamiliar with the ins and outs of the PB.
If the FETs were external, then the proffieboard wouldn’t need more than an amp or so, with peaks up to two amps.
I’ve considered various 2/3/4 pin connectors for use on the proffieboard. The idea would be to use 3-pin connectors for accessory LEDs and buttons (2 buttons in one connector), 4-pin connectors for serial, I2C and USB.
If we’re considering external FETs, then maybe I could also use a 4-pin connector to an external 3-fet control board.
Ideally, these connectors would be smaller than solder points, so that the proffieboard itself would become even smaller.
Personally, and given my short install experience, I think that the compactness of a single M.2 16.5mm with 3 to 6 FETs would be perfect. You just connect everything to that board (a bit like the CFX but with big pads for the FETs) and you can easily take out the board and reinstall. Having that second board would also simplify cabling since everything related could be close together.
I think the wiring will be a bit more complicated, but it should definitely be neater. The big motivation for me is to get the connections to the PB looking nice, without little pins stabbing up from through holes, and without make it so that it’s easier to assemble the whole wiring system and to remove the PB for reprogramming, maintenance on the saber, or whatever. Could make it so that future revisions of the board could just be dropped without having to do any additional wiring, for example if the processor got a major upgrade that would allow more frames per second to a zigzag blade (random example).
You shouldn’t have to remove your proffieboard to reprogram it.
If you can’t access the USB connector where it is, just create an extension connector for it. (Like the graflex helper board I use in my K4 saber.)
The bourns battery connector is an SMT part, so you’ll need to put it on a PCB, which you will need to solder wires to, which means you haven’t really gained much.
looking at the bourns connector 3d model, I think it would be easy enough to solder directly to the pads. It definitely still needs something to sit on to keep it in place, but that doesn’t necessarily have to be a pcb. That said, pcbs are plenty rigid, and probably better than using 3d printed abs or pla to keep it in place.
I’m looking at M.2 and similar connectors also, and they might work. single edge of connectors rather than two edges, simple pop in pop out. That idea is growing on me too.
m2 connectors are used in the sparkfun micromod series of products.
I have some for experimentation. Unfortunately the CPU modules are too wide to fit well in a saber…
Is the m.2 connector itself too wide? If so, what if it the board was set up so the m.2 connector was on the long edge rather than the short edge, so that the connector would be parallel with the axis of the saber’s cylinder?
M.2 connectors have many possible sizes. The most popular is the 22mm of width, which is a bit too much for the proffie (17.78, IIRC). But there is a version that is 16.5mm that has certain level of usage, so it could be considered an off-the-shelf part.
The more I think of it it would only work if the Proffie itself was significantly reduced in size and the connector allowed for an easier soldering. Because, to be frank, the more sabers I install the more critical size and cabling routing I find. I’ve avoided practically every possible use of connectors because of size and routing limitations. Since human hands are not getting bigger, I don’t really see much point unless it enables something that allows smaller board and easier soldering.
IF the board was connected though a ribbon and it could be stacked over the soldered board, then it might be justified.
I did some googling and found that there is also a hypothetical 12mm wide m.2 module. However, it seems that all m.2 modules plug into the same 22mm wide connector. Rather than having different sized connectors, the standard defines 12 different key locations, with each key blocking off 8 pins. So, tl;dr: less wide modules won’t benefit us any because the connector is the same width.
So that leads back to the idea of having the connector sideways. That would result in an m.2 PB that has the connector on the side, and which is probably somewhat longer than the normal PB, to make up for the room taken up by the connector. HOWEVER… if it’s long enough, say… 50mm? we could cram TWO m.2 connectors onto the card, and have double the number of pins and therefore the ability to handle more current.
It’s not going to happen unless you design your own proffieboard though.
Having an easily removable proffieboard is a good idea, but for that idea to become reality, it must be a solution that can co-exist with soldering in the same design, or be so much better that nobody really wants to solder anymore. Since these connectors will almost always take up more space than soldering, it’s unlikely to replace soldering completely.
That said, I will also point out that when you use an M.2 connector, there might be enough space between the two boards for some board-to-board spring connectors, which could potentially handle a lot more current than the M.2 connector.
oh that’s a really interesting idea… so the m.2 connector and screw hold the board in place so pogo pins or other spring connectors can maintain contact. Honestly though, I was really just assuming i’d have to learn kicad and make a custom board, then get a very small batch of like 10 made. If I were to go the m.2 route anyway. For just pogo pins, I’m hopeful that I can find pins and contacts small enough to work with the existing solder pads. Then it would be an easy mod for anyone with a regular proffieboard.
Either way, I’m gonna have to learn KiCAD one of these days, so might as well do it now. I actually have a license for Altium burried somewhere… I got hooked on the idea of making an open source bicycle power meter a couple years ago, and started to dig into that. Then I saw a squirrel or something shiny and that project landed in the infinite to-do pile with all the rest.
