I’ve got Raspberry Pi computers, and like to use the PoE Hat so I don’t need external power supplies, but it’s really difficult to add boards with this setup, because the PoE HAT has to be the first board in the stack and also the last board in the stack, as there are no extended-pin options.
Here’s a picture of the two boards stacked together, note that there’s a gap between them of about 2.7mm, not quite enough for a board with a passthrough socket, but plenty of room for a board.:
So the obvious solution is to make a board that’ll fit in that gap, and solder it in place before adding the PoE HAT. I’m working on my first of those boards, using the Connector_PinSocket_2.54mm:PinSocket_2x05_P2.54mm_Vertical part, and it looks like it’ll work.
However, that’s a pretty permanent solution, and I’d like to use a friction-fit board with plated through holes that’ll make a good electrical connection when pressed on, but still be removable if necessary.
Before I go re-invent the wheel, does such a thing already exist? The Pi uses a ‘standard’ .1" header with square pins around 0.5mm/.02" square, if that helps…
I suspect I need a new symbol and footprint, and while the symbol looks ‘easy’, the mechanical details of the footprint look really difficult for me. Is there a way to take an existing footprint (like the one above) and modify it for slightly different through-hole dimensions?
No. You MIGHT be able to get this to work once, but I really doubt it would be reliable, and if you separate it the pins and/or holes will have deformed enough that it will not mate again.
The answer is yes
It took many thoughts and board runs to finally get the solution, but it is actually both better and easier than you think. I developed my own power supply UPS for the PI and use the solution myself. It is reusable/removable for a number of times depending on how well you do the process, and, it is perhaps the cheapest and strongest way to mount a board to the pin header.
Yeah, I’m happy to throw out the board if I have to de-mate them, but throwing out the board and the Pi it’s connected to seems a little over the top, and desoldering would be a whole nother nightmare…
So if I could get the desoldering to work without tinning the gold pins, that might be OK, but it might be difficult to get the solder out and break the pins loose without the solder wicking up the pins.
For temporary connections & experiments, you could simply solder 2 male headers back to back to make a gender changer for the POE board and work with standard IDC flatcable connectors.
Male flatcable connectors do also exist.
Often you only need a few wires to connect, and it’s not too difficult to solder solid enameled wires to the “root” of the connector on the Raspi. You can probably also lift the black plastic distance holder with a screwdriver to make more room, but always put a connector on the header if you want to solder something directly to the Raspi pins to prevent the pins from moving.
I prefer to work with solid enameled copper wire for stuff like this, and you will need a temperature controlled soldering station at around 400 Celcius to burn of the lacquer (Ventilate well) first, then use a lower temperature to solder the wires to the connector. Working with loose wires has the advantage it’s always easy to modify later.
Oh, I see, extension pins on the GPIO headers so you can stack another board on top of the PoE HAT, and then different extension pins for the 4-pin PoE header. And then the board that goes on top has to keep clear of the PoE HAT fan. I remember looking at this before, but being unable to get the extension pins in the same height from a US source.
I will tell you, but you have to promise that youll report back to me on any improvements you make/find… took me years and i still haven’t finished my ups for manufacture. No soldering, but mild difficulty removing. Lemme get a video up for you. Do you have a personal email?
