TAG Connect SMD "Connector" for Programming

[Josh-B-1209]

Version Number

Latest (V4)

Enhancement

Potential enhancement

Description

Noticed particularly with feeder pcb's that a physical connector is used for programming. I recommend using tag connect, Website: https://www.tag-connect.com/, it is essentially an smd footprint comprising of 6, 10 or 14 circular smd pads arranged in a 2 by X rectangle.

The idea is that since the feeder or even the main pick n place motherboard microcontroller would only need to be programmed once, it doesn't make sense to use a physical connector like a jst for example considering it adds to the BOM cost when making a large number of boards.

Tag connect sells cables which on 1 end has an arrangement of pogo pins and 3 alignment pins which will correspond to the smd pads and small alignment holes on the pcb. This allows a pcb to be programmed by a user without needing to first solder on a connector or... automatically with a pick and place machine with a custom toolhead (: .

Voltlog Video Explanation and Demonstration: https://youtu.be/9-e_gcYaEM0?si=SZOb3TbV-59RbMbt&t=158

(It should be noted that Tag Connect footprints are included in Kicad's footprint and symbol library by default, no need to download or create.)

Suggested Solution

Replace JTAG Headers with Tag Connect SMD Pads

[daveismith]

Personally I'm not the biggest fan of the tag connect having used them in other projects. In fact it came up as undesirable in an hardware review for a team I'm part of recently with the firmware / software folks not being fans but the HW folks thinking it was a great idea. The particular complaints were that connecting / disconnecting the tag connect cable (with retention clips) is cumbersome and that the cables are significantly more expensive than standard 1.27mm cables / connectors.

For manufacturing in small quantities it's a reasonable solution which doesn't add board cost. Once you get to medium or large scale production, you'll likely be using a fixture with pogo pins that would replace the tag connect so it doesn't give a lot of benefit. A fixture of this style can either hit testpoints or the pads where you would typically populate the connector.

Having said all of this, I understand that this is going to be an item of personal preference. If there's a footprint which can allow both tag connect & soldered connectors it may provide a middle ground which could make both those who like and dislike the tag-connect system happy.