Help with wiring/cabling solutions from usb programmer to dev board - Page 1
Forum section: electronics / beginners

author: whitehorsesoft
author_rank: Newbie
timestamp: December 04, 2024, 01:16:59 am
content: Thought the standard female/female jumper cables would do fine for connecting header pins on USB programmer to header pins on breakout board, but they aren't holding up. Power blips when connected, and things like signals across the wire are suffering as the connector gets looser and looser from use. I know the electrical tape doesn't add to the professionalism here but seems like really there's a deeper problem.Not really plugging and unplugging a ton, but a few times a day.Do I need to get some IDC cables and connectors? Something that locks in place? I'm hoping to keep this in "hobby" budget range as you can probably already tell.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 04, 2024, 02:47:18 am
content: some projects have an integrated st link on themsome nucleo boards too .... you can make permanent connectionsor build a connection / interface board instead of using dupont wire who fail over time ??

author: shabaz
author_rank: Frequent Contributor
timestamp: December 04, 2024, 02:55:40 am
content: There's a good chance it's due to that purple/gray/white/black ribbon cable assembly not being very good.Generally, using pin headers is reliable for me, but I usually make up my own cables (using sockets from a distributor; it's still low-cost, since you mention hobby range pricing. I use the sockets shown in the attached photo, good price-performance with them, I've used thousands of those. It needs a crimp tool.You can buy good quality ready-made cables, I suggest at least "Adafruit" ones should be of reasonably quality. There are other vendors/manufacturers too.Also, perhaps your pin header on your proto board may be oxidised. Worth buying those from a reputable source too. Adafruit stock those too. I don't often buy from Adafruit, but they are known for these hobby supplies, and will be of OK quality.If you're inserting frequently, then for convenience, you may prefer to make up a dedicated cable, or use a ribbon cable assembly, and use a double row header on your proto board, in an arrangement compatible with using the ribbon cable. The ribbon cable assembly can be purchased ready-made (e.g. again Adafruit might stock it), or, it's not too difficult to self-assemble, but you need access to a vise, to gently push in the IDC connector onto the ribbon cable ends; needs a bit of practise the first time, i.e. a couple of spare IDC connectors for that.

author: whitehorsesoft
author_rank: Newbie
timestamp: December 04, 2024, 09:00:33 am
content: QuoteSince I only need four wires, is the double row header recommendation more so that standard ribbon connectors (with double rows) can be used, or more so that there are physically more pins (some unused) to grab on to and hold the connection with?

author: PGPG
author_rank: Frequent Contributor
timestamp: December 04, 2024, 11:33:16 am
content: Quote from: whitehorsesoft on December 04, 2024, 09:00:33 amRecently we decided to use Micro-MaTch connectors to connect debugger to PCB.

author: shabaz
author_rank: Frequent Contributor
timestamp: December 04, 2024, 07:55:49 pm
content: Quote from: whitehorsesoft on December 04, 2024, 09:00:33 amHi,Exactly that, both reasons, just for convenience mostly, although it can help be a bit more physically rugged too with the extra pins.A different connector is a good option too. You could use a ribbon cable assembly cut in half, and attach the desired custom connector at the cut end, and just trim back slightly the unused wires in the ribbon.

author: whitehorsesoft
author_rank: Newbie
timestamp: December 05, 2024, 02:25:19 am
content: > Recently we decided to use Micro-MaTch connectors to connect debugger to PCB.I love the concept and seems like it would be a great match for my need. But looks like those would be harder to crimp than typical IDC - do you use a custom crimper for them?

author: tooki
author_rank: Super Contributor
timestamp: December 07, 2024, 02:17:51 pm
content: Fundamentally, the root issue you’re running into is the deplorable quality of most no-name “DuPont” female contacts. They really only handle a few mating cycles before the contact leaf spring permanently deforms and has no holding force.These days I basically consider them fundamentally single-use, ok to use for 2-3 cycles, so basically for installing into a gadget for internal cabling.The Farnell 2226TG contacts mentioned above look the same as generic DuPont, but perform much better. I suspect the 2226TG are either rebadged Harwin M20, or a high-quality clone of those. I use M20 at work.The absolute gold standard in DuPont-style contacts are the Mini-PV series, which is now sold by Amphenol, but was invented by Berg, and was indeed owned by DuPont for a while. Mini-PV uses a separate leaf spring inside each contact, made from a different alloy than the contact body. They are rated for 500 mating cycles, which means they’ll actually last even longer for undemanding applications. (Amphenol has stated that “PV” stand for “perpetual virgin”, given due to their design for long life.) I use real Mini-PV for making test leads, logic analyzer cables, etc — basically, wherever a nice strong fit is required over many mating cycles. But they are tricky to crimp without the official tools, which are $$$$. (At home I crimp them, with some fiddling, in a tool that works beautifully and without fiddling on generic DuPont, M20, etc. At work, I can borrow the official tool from another lab, luckily.)Unless you are pressed for space, I would use the same 10p box header as on the programmer itself, so that you can use a simple IDC ribbon cable. You don’t need all the pins but they’ll provide additional mechanical stability. The IDC cable and connectors are cheap, fast and easy to attach without special tools (a simple bench vise works great). Do yourself a favor and buy the IDC connectors with strain relief so that you can attach pull tabs, which let you unplug without pulling on the cable itself. (E.g. 3M part 3490-89110 or TE 5088450-2.)