Small JTAG connector

[IDEngineer]

Yeah, we favor the legless version most of the time. But I just spec'd the legged version on our most recent board, ironically because things are tight and getting the connector in and out will be a PITA. This way once it's snapped in, it will stay until we intentionally remove it. It's also a board that gets installed into a potting box with corner screws so accessing the back for a retaining clip will not be convenient. The legged version was the perfect solution.

[gussy]

How hard is it to make a footprint in your preferred EDA package?

It's not hard? I make all my footprints regardless, but the problem is what's provided is worse than useful, it's confusing. Yes I'm sure they don't have Altium and every other CAD package, but they probably also don't draw their own copper wires or make their own injection molding tooling in-house, but they pay someone to do it, because they're a business. How much would it cost for a few hours of a contractors time to make an official verified footprint for a dozen of the most popular CAD packages? I'd say less than $1k even at US rates. Is there not enough margin to invest in high quality documentation and supporting footprints? That's my point.

To be clear I'm not saying they have to supply footprints, lots of connector vendors don't, but if they do supply something it should be verified and correct. Imagine if Molex supplied 15 Altium footprints for a connector and labeled some as "probably better"

FWIW someone further up the thread said they didn't understand the hate for TagConnect. I'm just answering the question of why some people don't like it. It's clear some people here like it, and I can think of at least a dozen collogues who don't like it. YMMV, use whatever works for you.

[jnz]

The tag connect footprint is extremely easy. The hard part I’ve found is if you are using the leg version, that unless you go tiny with your vias and traces that you may have a tough time routing the 10 pin version in some scenarios.... fan it out a little before you start.

[Bassman59]

The tag connect footprint is extremely easy. The hard part I’ve found is if you are using the leg version, that unless you go tiny with your vias and traces that you may have a tough time routing the 10 pin version in some scenarios.... fan it out a little before you start.

True! The thing I just did with the legged 2050 was an SiLabs micro with the C2 interface, so it used pins in the middle of the connector. Getting around the leg holes is a challenge because of their size.

[bson]

We have a new policy now, we review ALL footprints no matter what the spec sheets claim. Just another part of doing business. So having to create a footprint for a program/debug connector is really a non-event.

Yeah, agreed.  What I do is print the footprint at 1:1 on a laser printer and check under a microscope with the actual part.  Nothing makes one feel dumber than getting a board and finding out a footprint isn't right!    The laser printer is surprisingly accurate dimensionally, and works well down to 0.5mm pitch parts.  The worst offenders are custom shape QFNs, with oddities like specifying distance from the package center to outside the last pad and the space between pads but the pad width itself needs calculation. Human math is always error prone and making a mistake when juggling dimensions is surprisingly easy.  It only takes a minute or two to actually check though.

[poorchava]

I hate the 1.27 pitch connectors. Expensive, easy to damage, cables are expensive from normal sources (not AliExpress).

I use Wurth Elektronik's SKEDD. For STM32 a 6 pin fits nicely with STLink that is found on Nucleo boards. I work mainly power electronics nowadays, so debug probes are largely a consumable item.

For C2000 i just use bigger variety of SKEDD.

If space is at premium, then a few cias for poppins are enough. You can solder magnet wire to them for development.

[ajb]

I hate the 1.27 pitch connectors. Expensive, easy to damage, cables are expensive from normal sources (not AliExpress).

I've started just buying the bare cable and connectors.  $7 for 10ft/~3m of cable and about a buck each for the connectors, and I can make any length/orientation I want.  All of the 50mil IDC connectors I've seen have pretty close guides for the cable so they're very easy to install.  The connectors can work loose over time, apparently due to the latches that hold the connector closed around the cable wearing, so I've tried a dab of super glue on the ends of the latches on a recent set of cables as an experiment, we'll see what happens over time.  I haven't had a cable fail due to anything else, and I tend to abuse them a fair bit 

cable: https://www.digikey.com/en/products/detail/3m/3756-10-100/5308218
connectors: https://www.digikey.com/en/products/detail/cnc-tech/3230-10-0101-00/3883465

[gussy]

(...) cables are expensive from normal sources (not AliExpress). (...)

It depends on what your idea of expensive is, but these are relatively economical and easy to source at $2.95 https://www.digikey.com/en/products/detail/adafruit-industries-llc/1675/6827142

Almost as cheap as building your own cables with the links above, though if you need custom lengths then building your own is a good option.

[S. Petrukhin]

Let's update the topic bit.

Friends, I found a good connector. It is similar in principle to the Tags-Connector and Wurth Elektronik ASKED IDC: it is attached to the bare holes in the board, but unlike the others, it has retainers.
Not thin plastic teeth hold it on the board, which will eventually be wiped off, but there is a retainer.

I chose 8 pins (2x4), there are 2 rows of options from 2 to 8 pins each (4-16 in total).
Called: PCB direct plug, Push-in spring connection, Patch: 3.5 mm
Type: SDHC 1.5/4-PV-3.5
Number of contacts: 2 rows in each 4
Catalog code: 1848668
https://www.phoenixcontact.com/online/portal/ru?uri=pxc-oc-itemdetail:pid=1848668

[tszaboo]

Let's update the topic bit.

Small connector: 21mmx 17mm x 13mm.
You know, we used to have this joke:
"- Why isn't there any microelectronics production in russia?
 -  It doesnt fit through the factory door."

[S. Petrukhin]

Let's update the topic bit.

Small connector: 21mmx 17mm x 13mm.
You know, we used to have this joke:
"- Why isn't there any microelectronics production in russia?
 -  It doesnt fit through the factory door."

Yes, it is quite bulky and is unacceptable for compact devices. But for my industrial design, it is quite applicable, not much more than the usual IDC. I will try to use it in the next device. 

[harerod]

Quote from: Bassman59 on January 14, 2021, 07:45:55 pm>Quote from: jnz on January 14, 2021, 05:49:58 am

The tag connect footprint is extremely easy. The hard part I’ve found is if you are using the leg version, that unless you go tiny with your vias and traces that you may have a tough time routing the 10 pin version in some scenarios.... fan it out a little before you start.

True! The thing I just did with the legged 2050 was an SiLabs micro with the C2 interface, so it used pins in the middle of the connector. Getting around the leg holes is a challenge because of their size.

* * * *
I've been using the TC2050-IDC for years and on dozens of designs. For the escape routing I use 150µm traces. The distance between the guide holes and those traces violates my normal design rules, but I have never had any issues programming a controller.
Since the programming interface is used during initial programming, advanced trouble shooting and for development, the reliability of those traces is not that critical.
I find the TagConnect a great solution that doesn't incur a per board cost. Not having a header (a.k.a. antenna) on the board is a nice bonus regarding EMC.
I have been using the same TC2050-IDC-cable for years, no stability problems. Applications are mostly JTAG, low current power supply, serial interfaces, etc..
My customers' manufacturing operatives seem to break the clamps on occasion. Therefore, when programming only, the TC2050-IDC-NL, which is being held down during communication, is a good option. When handled correctly, there is minimal wear on the TagConnect.

For fully automated mass production a board would feature additional pins, which are contacted by a bed of nails type test adapter.