deskthority

Note: The small blue PCB in the pictures is just there to illustrate what everything looks like fully assembled. The socket adapter is the main item.

Although the HC-XX and HM-XX type Bluetooth modules of Chinese provenance have been widely available and highly popular for years, there are no solderless socket adapters commercially available so you can just slap them onto a breadboard for a prototype or DIY project.

I made a couple of these because I got tired of fiddling around with tiny wires or soldering the module to a breakout board without the possibility of removing it safely if I need to. If you are looking for a way to securely add and remove one of those 27x13 mm Bluetooth modules to a prototyping circuit, you might find this useful. They're 20€ per kit + 5€ for shipping, if anyone is interested.

The socket adapter basically consists of a PCB and spring contacts in lieu of solder pads and a laser-molded, screw-on acrylic bracket to press the module's contact pads onto the spring contacts. There is a total of 34 spring contacts which are split up into two rows of 17 pins each, pitch 2.54mm (standard breadboard pitch).

The module in the picture is just an illustration, the socket is the main item. There is no need to target a specific module here. As a matter of fact, targeting a specific module would pretty much defeat the purpose of a universal socket adapter. All HC-05, HC-06, HC-08, etc., likewise all HM-10, HM-11, etc., modules have the same physical dimensions (ca. 13x27mm). Pinout varies slightly, but it does not matter here. It doesn't even have to be a BT module, could be any other kind of module. Even the length does not matter, it could be shorter, say, 20mm in length.

The socket adapter allows you to place your module directly onto a breadboard. Without a socket adapter there is no easy, reliable way to access any pin you like short of soldering them onto a breakout board. The problem with soldering is that you will have a hard time removing the module, as anyone can attest to who's had to do that a couple of times (s.a. myself). Industrial multi-layer boards with huge ground planes are a nightmare to rework with a hot air gun, especially if there are no thermals. There is also the risk of frying something on the module or the motherboard if too much heat is applied to remove it. This stuff can get pretty messy.

As far as being able to access all those pins is concerned, those modules are usually based on (relatively) powerful and versatile SoCs with lots of GPIOs that could be used for all kinds of projects, not just as pure add-on BT radios. For instance, the chipsets used are very much capable of running a keyboard firmware on their own, or anything else you like. If you want to make use of lots of GPIOs, you need lots of (in this case) spring contacts.

Please do not hesitate to contact me if you have any questions or suggestions.

reserved

People over at Geekhack seem to be having a really hard time understanding what I'm offering here. I hope it is clear to everyone who's reading this that it is not about the depicted BT module (blue PCB), but the socket adapter (green PCB with spring contacts). You cannot buy such an adapter anywhere except here, not even from China. =^o

bump

bump, curious to see how this goes

haha, well, the socket adapters work just as I had planned and I have been using them productively for a while now for BT development. Apparently there are two people watching my Ebay listing, so I assume there is *someone* out there who thinks this could be useful, heh. =^p

bump

btw, here's some illustration of the 'design' process. I've include a picture of a very interesting alternative approach by WDWHITE@Thingiverse. I would have loved to try my hands on that, but, alas, I don't own a 3D-printer and don't find them overly useful or interesting, so I had to rack my brains to find an alternative approach. Also, while I love WDWHITE's idea because it looks neat, it's actually harder to build than it seems at first glance as it still requires drilling after printing, sourcing suitable spring contacts - NOT a trivial task, actually - and a PCB on top of that. I can also imagine that the pins on a printed receptacle-type socket will not last as long as the spring fingers I use, which are much more rugged (I hope) than the delicate spring contacts on a PLCC socket adapter (I've irreparably distorted and broken a bunch of these on various occasions).


(1) is a piece cut off of a Cherry keyboard PCB, probably a G80 or something, you can still see the holes where the LEDs were. I didn't have a proper breakout board and no tools to make one at hand, so I cut off this piece, removed the solder mask and cut 'traces' into the copper layer with a Dremel. That's about as quick and dirty as it gets, I presume. Rather dirty than quick, but it worked! Not a real socket though, rather a crappy breakout board.

(2) was my first attempt at making some sort of solderless socket adapter when I started fiddling around with wireless modules. That's what I worked with while working on the Blusb project. A piece of perfboard with some extra holes drilled so that I could mount spring contacts I had removed from a PLCC socket at the required pitch. It worked nicely, sometimes. Other times not so much. PLCC spring contacts are very delicate, unfortunately, and tend to break rather than bent which can make modification for other purposes than intended a fiddly and frustrating exercise, especially on a piece of perfboard. After removing a module and inserting a different one I often had to spend 10-20 minutes getting one or two faulty contact springs to make good contact again.

(3) is the current design, a true solderless socket adapter, which has none of the flaws of the earlier 'contraptions'.

OK, so one guy has bought one of these and seems to be quite happy using it (as am I). I've asked him to post some feedback I hope he's going to share his experience with everybody sometime soon.

knurled screws now optionally available!

this thread needs a bump!

Very useful. I bought one to program HC-05 and HC-06 boards without soldering them, since I use it to modify the firmware. After this operation pinout changes and then I can solder power supply and signal wires without having to desolder them from other pins. This way I don't risk to destroy the thin contacts. Really useful and very easy to manage. It may seem expensive, but I consider it a nice bargain since it saves me time and boards.

I still have some of those left, too, so let's bump this thread again!

Bumping this thread after a while, just to let you know the offer is still active.