Here are the results of my Pogo Pin testing: The best fit is Tip B (sharp tip), 1.27mm pitch, 4 pins, single row. Here's a video of the Pogo Pins connecting PineTime with ST-Link v2 (compatible)...
https://www.youtube.com/watch?v=K5GgUlv-1SI
Note that I had to push the pins in before sticking the Pogo Pin package to the base. The narrow sharp tip doesn't provide good electrical contact with the wider SWD holes. Pushing in the pins and tilting at an angle will provide better contact. (Also the Blu Tack putty will maintain some pressure on the pins)
There's a chance that the electrical contact will be lost after a while. Reattaching the Pogo Pins as shown in the video will help. You can see the gaps between the Pogo Pins and the SWD holes...
https://twitter.com/MisterTechBlog/statu...75936?s=20
I tested other tips, but they don't fit the SWD holes. These tips were likely designed to be used vertically, not at an angle like ours...
https://twitter.com/MisterTechBlog/statu...56800?s=20
So my recommendation is Tip B. It's not perfect, but it's a lot easier for first-timers to use this. (And I have seen so many problems reported in the PineTime Chatroom ;-)
Here's the link where I bought the Pogo Pins. Right now the price is US$ 4.50, excluding shipping...
https://item.taobao.com/item.htm?spm=a21...9323749230
