A lot of modern PCBs have small pads with no components attached. They are often used as test points, JTAG ports, or programmer connections. There’s no connector on the board, just pads. To use those, test equipment and programmers utilize pogo pins. These are small pins with a spring inside, reminiscent of a tiny pogo stick.
To use pogo pins effectively, you need a way to hold them in the right position and something to put pressure on them while they are in use. [Joshua Brooks] used a strip board to hold them in place and clothes pin to keep the pressure on them.
The strip board is handy because it allows you to easily attach a wire to the pin without having to solder the wire to the pin. Some hot glue, cable ties, and heat shrink round out the clip. This is mostly useful when you have a very tiny board or lots of boards where you don’t want the expense of a connector on every one. In [Joshua’s] case, he was programming a lot of AVR boards.
We’ve seen a lot of 3D printed pogo solutions. If you have a laser cutter, you might be interested in an OpenSCAD tool.
Love it, great simple solution to a problem a lot of us have ran into.
OpenFixture project might be of interest and help if you have the PCB design files.
https://github.com/ebuller/openfixture
That is actually the last link in the post (well, indirectly though our earlier post about OpenFixture).
Designing beds of nails and hand soldering them, pogo pins brings back nightmares!
There are actually sockets for them, which are designed to be soldered or wirewrapped. Proffesionals use these sockets as pogopins are only rated for like 1000 insertions. Hard to replace one that is soldered in. I found out when I visited HQB with a hackercamp.
DirtyPCBS.com are selling the sockets here: http://dirtypcbs.com/store/designer/details/ian/12/dirty-pogo-pins
I just had some acrylic laser cut for a jig by the end, the last one i did even combined a soldering and testing jig!
I had big problems with the pogo pins from Tag Connect. They always got loose. Normal connectors are much better, also for debugging.
Better is subjective. Of course there are issues if you are attempting to hold it by hand, but they really excel when combined with some sort of jig. In a manufacturing environment, a test/programming fixture with pogo pins will almost always win out. You can make all of your contacts on dedicated test points or existing vias, saving board real estate and BOM cost. The mean time to failure on most female headers, especially small ones, becomes extremely important when you’re producing any significant quantities. Spring loaded pins will typically last longer, and replacement is simply a matter of removing the old pin and sliding a new one in. Not to mention how much faster a properly designed fixture is, compared to fiddling with most connectors.
If you have only a two PIN bootloader (Serial IN/Out + GND) you could cut a bracket to do the pogo part… (cheap & dirty)
https://sebastianfoerster86.files.wordpress.com/2016/05/img_3425.jpg
But in your case you do not contact any IO line but two GND pads of the USB socket. It would be difficult to connect tighter spaced pads with this crude arrangement.
Sure, it is GND on a USB and only an example pic. At least a diameter of 2 mm per pad is required. But if I see the picture in the article it is a kind of small ;)
If you cut a 2,5 mm² wire diagonal it results in really sharp edges and good connection for a while…
Hm… A wooden clothes-peg has a flat surface. I wonder if there a small solderable nails, then add some superglue (the stuff that you have to mix together before use) and maybe you can get a decent result with more pins.
Injection needles are not solderable (hint: use them to push away solder to clean holes for THT, i recommand grinding or cutting the very sharp tip before!), but maybe cut the sharp end, insert some fine wire and bend it at the end to make a contact (with some heat shrink tube to maintain in place and insolate the entire thing?)? And if you have a double-sided board you could put the GND on the other side of the board and add some copper tape inside the clothes-peg.
Just some ideas…
or maybe just wrap wire around the needle and put heat shrink tube over? The currents for programming etc are really small.
Is a clothes peg called a ‘clothes pin’ in Merica? We call them pegs here.
“Clothes pin” is a pretty generally used term here in the states. But there’s at least three variations.
Two pieces of wood and a spring seem to be most common, but variations include a plastic version as well. There’s also a simpler variation that is just a single piece of wood with a slot. I’ve seen that in both round and rectangular cross sections. They work ok for hanging clothes, but they seem to find more use in as raw material in crafty projects.
Seasonally relevant example : http://1.bp.blogspot.com/-mzBiGxLhydM/Tt5CAX0np5I/AAAAAAAADGw/LXXeJRPWXTE/s1600/063.JPG
I made a small jig for my pogopins – I chose to skip the PCB entirely:
http://embryonic.dk/wordpress/?p=782
I just posted a 3D build where I used pogo pins as battery contacts. : )
https://www.youtube.com/watch?v=LUnXYKnuUyA
http://i.imgur.com/J3vajLD.jpg
I have pogo pins that fit nicely into those machine-pin sockets (or the end of a cable connector). Passing them through two pre-drilled boards gets the alignment right if you’re going for 0.1″, and the wood and hotglue gives you something to grip on. This particular adapter ends in an AVR 6-pin ISP style header so it can just plug in on the end of any programmer.
Still, it could use a clip like the post here. I may have to get the hot glue gun back out.
We have used Tag-Connect pogo connector for JTAG in some projects. It is very handy but how can such a simple cable/connector be so ridiculously expensive :)