[IC] Solderless adapter socket for HC-xx, HM-xx BT modules (breadboard, Arduino)

[chanceman42069]

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).

This is more of an interest check than a product offer really. I will add more information as questions and suggestions start pouring in.

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

[chanceman42069]

reserved

[vosechu]

Looks amazing! Do the metal screws mess up the signal at all?

Also, is this a pro micro compatible pinout?

[chanceman42069]

thanks, I'm surprised to hear you like the looks of it - it's not a stock item, it's pretty much hand-made in my small basement workshop.

I don't know if the screws make any difference. This is supposed to be a development aid, not a replacement for a properly designed motherboard. If need arises the metal nut and bolt could be replaced by plastic parts, no problem. =^)

There is no 'pinout' here. The BT module is not part of the kit, it's just an example of what it looks like fully assembled. Did you mean something else?

[chanceman42069]

in case somebody is wondering I have been using less sophisticated contraptions in the past and I cannot remember grounded or ungrounded metal parts affecting the BT radio so significantly as to hinder application development, jfyi.

[suicidal_orange]

I don't know anything about these modules but that's a lot of pins for bluetooth where I would expect a couple of data lines, power, ground, and maybe an aerial or two.  If they are used as IO pins but there's no standard (as suggested above) I think you would do better targeting a specific module and making it pinout compatible - there are keyboard PCBs designed to take pro micro's and Teensy's so it could be a drop in replacement and appeal to more people.

[chanceman42069]

I'm sorry I don't see how I'm inviting these misconceptions (yet) but let me clear this up.

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.

[chanceman42069]

on a side note, anyone got an idea where else I could go blow my horn about this? I only know DT and GH, which are technically keyboard forums, not general embedded development forums.

[Findecanor]

There is no 'pinout' here. The BT module is not part of the kit, it's just an example of what it looks like fully assembled. Did you mean something else?

Of course there is a pinout, because it is designed for a specific MCU module!

What module is this? And what chip do they use? nRF52840 or something else?

[chanceman42069]

Of course there is a pinout, because it is designed for a specific MCU module!

What module is this? And what chip do they use? nRF52840 or something else?

No, absolutely not, and forget about the specs of the module, it does not matter. Once again, the socket adapter (green PCB with spring contacts) is the main item and the term 'pinout' is meaningless in this context. The BT module (blue PCB) is just there for illustration.
The module depicted has a specific pinout, correct. The socket adapter does not, it works just like a breakout board, just without solder. It does not matter at all what the pinout of the module is as long as it has the correct size. ALL HC-xx and HM-xx modules have the same physical dimensions.

I've changed the title of the thread, perhaps reading 'Bluetooth module' first was getting people confused.

[chanceman42069]

OK I do have two people watching the item on Ebay by now, even though I have not received any enquiries yet. I have been using these adapters productively for a while now and can attest to their usefulness. They work exactly as I had planned. Hence I'm bumping this thread again. =^)

[chanceman42069]

bump

[chanceman42069]

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'.

[chanceman42069]

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

[chanceman42069]

bump

[umbco19]

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 de-solder 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.