Re 3.3 Vs 5 in general.

The chip manufactureres do not give a hoot about most of the participants in this forum. Their interst is, justifiably, in the millions of chips users. What does the public want from the manufacturers: cheaper, smaller energy efficient devices.

To achieve this the voltage has been reduced and the result of the smaller geometry is
cheaper (more chips per wafer)
smaller (obvious)
energy efficient (less power due to smaller signal swings).

Now what must you do to cope with this:
No 'flywires'
multilayer board
efficient decoupling
often shielding
etc

As a result the industrial product has become better and the amateur problems has become worse. So, amateurs of the world: Shape up, what you could get by with 5 years ago does not fly any more.

Also, the weaaker my old eyes get, the smaller the chips:-(

Erik