MichaelMeissner
Senior Member+
I think the castellated smt might be the best.Wondering about best way to gain access to the bottom pins, when not used with external memory.
I can see a few different ways to get some/all of them:
a) Pogo pins - Sort of a pain especially with the .127...
b) Wondering about SMT connector. Maybe something like: https://www.digikey.com/product-detail/en/amphenol-icc-fci/20021121-00008C4LF/609-3694-1-ND/2209146 ?
c) Quick and dirty castellated smt. Not sure if I do one to put the new pins in line so could maybe plug into breadboard. Or just two rows just behind SDCard slot... May try to layout one or the other.
But now back to playing
Just for fun, I took one of my Sparkfun SOIC to DIP adapter (https://www.sparkfun.com/products/13655), and laid it out on the Teensy 4.1. It would require precise alignment and to have a deep enough solder to connect the board, In doing so, for the larger pad (near the middle row of pins), the holes for the DIP adapter seem to line up with the middle row of pins, which is not helpful.
I tend to think extending the 24 pins of the 4.1 by 4-6 pins on each side might be the simplest, and it would allow breadboarding. For just the memory pads, you would need the 5 common pads plus the 2 CS pads. But if you are going to do that, it may be useful to bring out on/off, program, Vbat, and maybe VUSB to the outside pins as well.