Making our own Qwiic Cables? Parts List

Qwiic System
1

Well, I wrote up a few minor revisions and now it again says “You can no longer edit or delete that post.” Even though I was literally in the edit post screen and was trying to update the subject and body to add more information.

So just going to post the post again with minor changes. Again, this is very irritating.

Engineers Precision Crimping Pliers PA-09 is a very nice crimp tool for manual jobs.

http://www.engineer.jp/en/products/pa09e.html

You will also need the connectors.

https://www.digikey.com/product-detail/ … M9234CT-ND @ $0.10 each at qty 1.

https://www.digikey.com/product-detail/ … WM2089-ND/ @ $0.20 each at qty 1.

Sparkfun says “SHR04V-S-B or equivalent” for the mating connector.

https://www.sparkfun.com/qwiic

That’s a TE 1470364-4 or JST part.

https://www.digikey.com/product-detail/ … 5-1379-ND/

Note that the 0874210000 pin says it is 24 to 26 AWG. So not sure it is within specification for a 28 AWG cable that Sparkfun uses? Sparkfun, why do you use 28 AWG cable? These connectors physically fit into the Qwiic style connector at least.

https://www.digikey.com/product-detail/ … 1561-1-ND/

The SHR-04V-S-B is 28 to 32 AWG, which is probably why they use 28 AWG and not larger?

Plus the wires. We prefer to not use PVC wire for various reasons but there are quality TPU ones out there. You will also need a strip tool.

https://www.digikey.com/products/en/cab … ageSize=25

Here are the SH series 2", 4", 6", 8" and 12" length prestripped and crimped wires. All black though. 28 AWG. Likely PVC but doesn’t say.

Knipex makes the 12 40 200 Self-Adjusting Insulation Stripper but there are others out there, including manual ones as well.

Still, you are looking at around $100 to $175 for a starter set to be able to make your own Qwiic cables on a manual but reasonably high quality basis, mostly because of the tools.

You can also buy precrimped PVC wires from Digikey and just make your own by pushing them into the connectors rather than needing to strip and crimp anything.

https://www.digikey.com/product-detail/ … 5-3077-ND/

Sparkfun uses cables that are single wires with some heat shrink over part of it. We prefer to use an outer jacket cable to better keep things together. Sparkfun uses 28 AWG wires. 24 to 26 AWG seem to be what that connector supports.

https://www.digikey.com/product-detail/ … 1561-1-ND/

Is the crimp that Sparkfun seems to use. SH series, $0.11 each, tin plated 28 - 32 AWG.

https://www.digikey.com/product-detail/ … 5-1379-ND/

Is the connector that Sparkfun seems to use. $0.14 each, white.

There are some good crimping guides out there.

https://iotexpert.com/2018/01/18/jst-co … -insanity/

http://tech.mattmillman.com/info/crimpconnectors/

Talks about the official (and quite expensive) professional tool (the WC-240).

Hope that helps summarize the hours of work we had to go through to actually figure out how to make our own custom length and material Qwiic cables.

2

Well, once again was trying to edit this to add the official hand crimp tool. Which is $1100+ in price.

https://www.digikey.com/product-detail/ … 5-2569-ND/

Doubt most people need it but thought they might want to at least know it exists.

3

Wow, who knew creating your own Qwiic cables involved so much effort! We appreciate you sharing your experience with the community. All of a sudden those pre-made Qwiic cables seem pretty great assuming they fit what one needs for their project.

On a side note, we appreciate the feedback on the editing issues you had addressed in your post. We have changed the editing time to 60 minutes, instead of 20. Hopefully, this eliminates the issue of getting timed-out while creating new topics and replies moving forward.

Thanks again! We look forward to more interesting topics such as this in the future!

4

Changing it to 60 minutes certainly helps. Thanks for cleaning up the prior post as well. Took a while to pull all this together then take extra time into sorting it out to be somewhat readable. It could still use some cleaning up as well though but we have already put more into this than we wanted to.

The pre-made Qwiic cables seem pretty great assuming they fit what one needs for their project. They are a bit expensive but they don’t work for us because they are PVC and in this application, PVC is not a suitable cable material. Plus we need custom lengths anyway, which Sparkfun doesn’t offer.

Still have a few unanswered questions though about the above information compilation. Need to verify that the 24 - 26 AWG connectors properly detent into the Qwiic ports but need to crimp them up first to test that. Will do that soon. They fit without the crimped connectors but nothing holds them in place. Will need to see if that changes once the cables are inserted.

Overall the Qwiic system is nice but it has some downsides and could have some of the details presented to customers by Sparkfun who are interested in looking deeper into it or modifying it, etc. Would also be nice if you had some “higher performance” Qwiic style connectors or shields or something instead of the UNO shield that doesn’t even work with the MEGA at all. The TXB0108 and TXB0104 chips doesn’t work well with I2C for example. We have yet to figure out exactly how we want to go from I2C native on the Arduino to the Qwiic system. The Sparkfun UNO shield (which is one of the few ways to easily and quickly add Qwiic unless you also go with a Sparkfun Arduino board that has it already on it) forces you to use the BSS138 chipset, which isn’t really suitable for higher speed I2C but at least functionally works with I2C. Unless you try to use it with a MEGA of course.

Something that lets you do higher number of connectors or easily deal with multiples of the same ID parts or cleanly deal with 5V to 3.3V as an option when the source is operating at 5V, etc. Would be nice if it was a simple form factor shield but had some options built in for example and also possibly handled extending SPI as well? Instead we have to sort of tack together literally 4 different Sparkfun items and even then it’s not really properly setup for high speed I2C and still needs modifications on top of that.

We just want to use the Qwiic setup as it does speed up development and does help let us focus more on the things that are better uses of our time than soldering things together or dealing with extra overhead. Just need to make a few improvements and would be great if some of these ideas could be incorporated into a product that handled that.

5

What’s your application where PVC cable jackets won’t work? It’s a pretty good material choice for cable jackets in most situations. The situations where it is not that also intersect with hobby electronics are usually interesting to hear about.

If you’re going through all this trouble with cabling, at what point does it make more sense to manufacture your own boards where you can choose an interconnect that easier to work with?

6

PVC is cheap. However, PVC is also normally a solid plastic (think PVC pipe). In order to convert it to, well, a flexible plastic you have to add plasticizers. Quite a lot of plasticizers by weight. Which are also typically cheap and more reactive (shorter chain phthalates or phthalate esters are cheaper but more toxic than medium or longer chain ones) and tend to be less friendly to living things. You are starting to see “DEHP free” as a common marketing term? Well, DEHP is the diester of phthalic acid and the branched-chain 2-ethylhexanol. It’s also a phthalate. However, you can also use DBP, DINP, DPHP, DIBP, DIDP, DINCH, BBP, DOTP, etc as they are all chemically similar phthalates (and then still market your plasticized PVC as DEHP free).

Same thing happened with Bisphenol A (BPA) in polycarbonate drinking bottles. They switched to a chemically similar product that’s technically not BPA so now they market it as BPA free but it’s basically still BPA. So “DEHP free” basically can translate to this is PVC but we use a slightly different plasticizer instead. Or it could mean it isn’t PVC.

https://www.rohsguide.com/

EU RoHS specifies maximum levels for the following 10 restricted substances. The first six applied to the original RoHS while the last four were added under RoHS 3, which takes effect July 22, 2019.

Cadmium (Cd): < 100 ppm

Lead (Pb): < 1000 ppm

Mercury (Hg): < 1000 ppm

Hexavalent Chromium: (Cr VI) < 1000 ppm

Polybrominated Biphenyls (PBB): < 1000 ppm

Polybrominated Diphenyl Ethers (PBDE): < 1000 ppm

Bis(2-Ethylhexyl) phthalate (DEHP): < 1000 ppm

Benzyl butyl phthalate (BBP): < 1000 ppm

Dibutyl phthalate (DBP): < 1000 ppm

Diisobutyl phthalate (DIBP): < 1000 ppm

Note that these 10 items are literally the only things covered under RoHS. They are the worst of the worst and of this list, as of July of this year, 4 of them are all phthalates. Note that you see DEHP free as a marketing term. You don’t ever see BBP free or DBP free nor is the average customer going to have any idea what that means either.

Point is, PVC cable is not skin safe or really that healthy in general. It is cheap and common though. There’s a few other downsides as well but the main reason for this application is skin contact safety but also smoke generation. PVC, if burned, is extremely toxic as well. HCl, dioxins, etc. It’s particularly nasty stuff. This wire here also needs to be LSZH and PVC is about as far from that as you can get.

PVC is cheap though and does insulate fairly effectively. But so do other materials that are now becoming common and off the shelf but more so in European markets compared to the USA. It’s just easier to make our own cables and also just use a different but off the shelf cable insulation at the same time. You can also now fairly inexpensively purchase silicone insulated cables as well. Also some pros and cons there as well but much less toxic compared to PVC, especially if you are going to be handling them or using against your skin for periods of time.

In production we will be making our own boards. This is the first prototype step that we are trying to rapidly iterate and assemble and hence the Qwiic system works well for that application. It’s not a big deal to simply select a different cable material now that LSZH cables are off the shelf and we are already making the cables anyway since we need quite a few different lengths anyway.

It’s just super annoying that Qwiic winds up not being that Qwiic to use in any way except exactly as they describe and with the main limitations of it glossed over and not mentioned somewhere at least. This isn’t the first time we have bought Sparkfun items to iterate things and been disappointed with things not being documented or fleshed out or outright ignored. At least they mention the connectors part numbers somewhere. Getting technical assistance from Sparkfun is also equally challenging. You call them and they basically try to wiggle out of taking to you at all, don’t really know anything deeply technical about the products and then tell you to post to the forums. Which then literally says wait 2 or 3 days for a response. Looking at the forums, it’s fairly clear that the staff of literally two doesn’t exactly respond to a lot of messages at all! The forums are not exactly widely used either.

Sparkfun kind of seems to want customers to help other customers for free. Which is basically what we did here. Not going to polish this Qwiic summary off or anything but I doubt they will either. We like the idea of open source overall and generally like supporting Sparkfun’s efforts to help everyone out but there are several things that could be done to improve this. Plus, Sparkfun is still a profit making endeavor so it’s not exactly a bilateral exchange. We not only make nothing contributing this but we likely help them sell more products and profit from our contributions. Then we reach out for assistance and they basically tell us to go figure it out ourselves.

Anyway, this is turning into a novel but the point is that plasticized PVC is a nasty material overall especially for anything around people or in skin contact applications. Feel free to do your own research if you would like, there is plenty out there but it’s just easier now (finally) to just buy a slightly different (and slightly more expensive) cable insulation, use that instead and move on.

7

Note that the official Sparkfun Qwiic connector contacts can come in two different part numbers if you order them directly and make your own. Sparkfun, do you know which ones you use specifically here with your official Qwiic cables? Does it matter?

H = High pressure / Insertion force

With “-H” = High-pressure contact type for a more assured connection with the mating post and to help prevent deformation of the crimped contact.

Without “-H” = Standard contact insertion force.

Digikey Part Numbers

455-2963-1-ND = SSH-003T-P0.2-H (High-pressure contact force type)

455-1561-1-ND = SSH-003T-P0.2 (Standard contact insertion force type)

As an aside, the 28 AWG contacts that Sparkfun uses with their Qwiic system cables do not detent or clip into the connectors either with no wires inserted. So presumably the crimps are what hold the connection in place?

Here is additional information from a presentation that breaks down the part number for the official Qwiic contacts a bit more.

S = Strip terminal / Chain terminal

The contacts are packaged in a reel for automatic crimping equipment. JST does not sell these loose.

A prefix of “MINI-” would indicate the contact is placed on a mini-reel for use with hand-held crimp tooling.

Contacts prefixed with (B) are made, and typically exclusively sold, in Belgium.

SH = Series name or series relationship identifier.

These are compatible with the SHD series as well.

003 = Applicable AWG (American Wire Gauge) range

002 = AWG #26 ~ 30

003 = AWG #28 ~ 32

005 = AWG #36 ~ 40

8

Made an error in the link earlier for one item. Please feel free to correct since WE CAN NO LONGER EDIT THE POST.

https://www.digikey.com/product-detail/ … WM2089-ND/

Should instead be 4 pins, which would be the following part

https://www.digikey.com/product-detail/ … WM2088-ND/

Accidentally linked the 5 pin part for the non Sparkfun 24 to 26 AWG connectors. Qwiic is 4 pins, not 5.

They are $0.21 each at qty 1 despite having 4 pins instead of 5.

However, more importantly, these connectors physically DO NOT fit into the Qwiic style connector though. So use the other linked ones if you want the cables to connect into the Qwiic connectors.

Also the Sparkfun cable housings seem to be black instead of white? Cosmetic difference there but doesn’t seem to be any different otherwise. Sparkfun, feel free to chime in if that is the case.

9

S = This is the color indicator of the housing.

S: White (natural)

M: Green

Y: Yellow

PK: Pink

BK: Black

T = Plating indicator

T = Tin-plating overall

GA = Flash [about 0.05 microns (2 micro-inches)] of gold-plating on the mating area only with bare material on the rest.

GI = About 0.8 microns (32 micro-inches) of gold-plating on the mating area only with bare material on the rest.

GU = About 0.4 microns (15 micro-inches) of overall gold-plating.

Note: Gold should not be mated to tin.

P = Material indicator

P = Phosphor Bronze (default)

0.2 = Maximum mating post / pin width

0.2 = 0.2mm

It looks like you can order this with gold plating but it is NOT the -H designation normally if you do so. So the connector is slightly different. Unclear if that matters here or not?

Also, the SSH-002T-P0.2 part appears to be valid but it is also not the -H designation.

10

The forum seemed to be reset earlier by accident so bumping this again because it deleted the post earlier when the forums seemed to go down? Not sure why it deletes posts that are already posted? Spent hours putting this together to let people know how to do their own custom QWIIC parts to elaborate on what was already available in case they needed to make their own custom lengths and silicone cables.

Guessing it probably thought it was spam or something? No idea. Agreed though that the Japanese link to their crimp tool isn’t exactly short but it’s also not a place to even buy the part either nor does SparkFun sell it either but it really does help make a QWIIC part on your own to your custom length and insulation.

Have not checked what has changed from 2 years ago now when I put this together but probably at least somewhat still relevant if you are trying to make your own QWIIC sockets and plugs. Please read the posts in total because it would not let us change or update them (and still does not).

First link changed for example.

https://www.nejisaurus.engineer.jp/prod … 3%E3%83%81

is now that Japanese link. https://www.engineertools-jp.com/pa092021 is now the English link of the PA-09 product but it does not let me update the link anymore as one example.

Not exactly sure “All of a sudden those pre-made Qwiic cables seem pretty great assuming they fit what one needs for their project” still holds true though, two years later either unfortunately as you still cannot buy these parts from SparkFun and can only buy their still PVC QWIIC cables with no option for a silicone cable that is both safer to use and far higher temperature supporting as well as not really being much more expensive either. Even Adafruit does not offer PVC free ones in their version either.