I have several products that use the standard ARM 20 pin JTAG programming connector. I decided to investigate downsizing to the ARM 10 pin to save a little space on a new project. It works, but most of my JTAG programmers do not have the 10 pin ARM connector option inside the casing. A few do. So, is the 10 pin not really used much? Should I not use it? Should I just stay with the common 20 pin I've used for years? Looking for input. Thanks. I also noticed the 20 pin to 10 pin adapters have been discontinued, so that might be a hint as well.
The 10-pin, 0.05"-pitch connector is widely used in many products & dev boards; in many cases, there simply isn't room for the 20-pin connector.
Plenty of 10-to-20-pin adaptors are available:
https://www.google.com/search?q=arm+debug+10+to+20+pin+adaptor
But an adaptor is simply passive wiring - it's easy to make one.
If you want to be aggressive regarding space and unit cost, you could consider using a non-standard connector. My company has been transitioning to a plug-of-nails connector.
https://www.tag-connect.com/product/tc2030-ctx-6-pin-cable-for-arm-cortex
https://www.tag-connect.com/debugger-cable-selection-installation-instructions/keil-ulink2
https://www.tag-connect.com/debugger-cable-selection-installation-instructions/st-link-v2
The disadvantage is that you always have to have an adapter. No OTS emulator will come with this naively. Also consider your opinion of single-sourcing.
The advantage is that this is accomplished 100% in layout - no unit cost for connectors, and the only space required is pads + holes (3 alignment + 4 leg/latch).
Our PCBAs also have multiple micros, so the cost+space starts to multiply.
One thing I would caution, if you choose to layout several of these in a row for multiple processors, make sure you orient them in a thoughtful direction. If you stack them right next to each other, after they are all plugged in, you won't be able to get your fingers on the release clips and they'll be stuck the board. We "may or may not" have made that mistake on one board set. :)
Of course, you don't have to have an actual connector at all - you could just have test pads, and use "pogo pins" to connect. This is great for manufacturing, but not so much for development.
The TagConnect Pieces mentioned is a kind of "half-way house" between the convenience of a connector for development, and the economy of no connector for production.
Here's one I prepared earlier:
Note that you can get "retainers" to hold the TagConnect so that you don't have to take up PCB space for clips:
For production, you just use the pads & pogo pins - you don't need the TagConnect.