Hello friends !
I just spent a few bad days troubleshooting weird problems with a new shield I was trying to address from a panda II. Several panda II actualy and never the same problem.
The trouble is so simple that I really took days to find it, so I thought about sharing with you guys.
So this is my conclusion after 2 days of tests: some shield stacking headers are NOT compatible between them, as bizarre as it sounds. The ones mounted on GHI panda II (at least) work very well with legs having a square or round section. However, those with rectangle/flat section (and the small side is very thin), like adafruit’s headers are not reliable to use. About 30% of the pins were not making a proper contact…
The same headers connected inside the big double long connector at the end of the panda II (D20-D52) are making good contact. However not with the arduino standard hearders on the sides !
I now understand why GHI is using 2 different connectors for its shields, for upside and downside