For (TAG) programming and testing, I don’t use physical connectors on the PCB but connectorless self-clamping zigzag connectors. The pin header of the programming tool is inserted directly into the holes. By the zigzag positions of the PCB holes, it provides lateral pressure, sufficient to grip the pins and allow good connection. For use as for programming and testing, it works fine, I have never experienced any contact problems.
I am an inventor and always wonder if something cannot be made better or simpler. For instance, the ISP connector, which is 2x3 header with a pitch of 2.54mm:
To connect to the ISP connector you could use an adapter with Pogo pins:
But the adapter must be continuously pressed against the PCB during use. Therefore I invented an alternative:
My solution has some advantages:
The construction is simple: By the zigzag positions of the PCB holes, the male connector pins press against the holes and make electrical contact. The connector is self-clamping. The idea is inspired by the Sparkfun 1X06_LOCK Eagle footprint.
With the mini 1x6 ISP adapter we can connect the zigzag ISP connector. The connector pins are thin and are suitable for the Eagle footprint. It is made compatible with the connector of the programmer USBasp.
I have added a key pin which prevents incorrect connection. Note that the other images are without the key pin.
The key pin is optional, so it can be left unconnected also.
You can download the Eagle library part at GitHub.