For me the problem of not having full electrical specs comes when stepping away from the recommended or approved way of doing things.jamesh wrote: ↑Mon Apr 02, 2018 10:42 amJust out of interest, what is the lack of information stopping you from doing? Huge numbers of people use the GPIO's successfully with the available documentation, so I'm just trying to see what particular circumstances you have that mean you are unable to proceed.
For example I can expect the Pi's GPIO to work as expected if I connect that to a MAX3232 or similar, but I cannot determine for myself what the situation would be if I wanted to use a current limiting resistor to interface to an 'out of spec' voltage.
I know I "shouldn't do that", "that's not recommended", "not best practice", but I want to know if it can be done, what the limitations are, and likely consequences if it is done that way, just as it has been done on many other microcontrollers and other logic circuits.
I am not interested that I should not do it, is not recommended, may be bad practice. I want to be able to assess what would happen if I should try it. It should be up to me what I consider acceptable for my use case. Without a full electrical spec I cannot make an informed decision.
That informed decision is achieved with other microcontrollers by referencing their full electrical specs. Without the Pi's full electrical specs one cannot make make an informed decision. That leaves experimenting in the unknown, risking unnecessary damage, or not even attempting it.
People can say I can't do it, or I can, the electrical specs are what would allow me to decide for myself whether I can or can't, should or shouldn't, would let me to assess the risk of doing that.
From a software engineering perspective; it is perhaps like deliberately not documenting 'rm -rf /'. Will that instantly do what might be expected or are there protections to prevent the damage which could be done ? Without the documentation one can only say 'don't do it' to be entirely safe or chance it.