(I know no caps an power inputs to arduino, or on voltage reg - I'll take care of them at build)
Or on the LED lines or on the IC. So you are asking if a faulty schematic is OK?
What is the 74LS505 doing? I can't seem to find that as a chip. If it is a port expander, why do you need it. The darlington arrangement driving the LED transistors is a bit unconventional but I suppose it might be alright. You could save yourself a lot of pull up resistors if you just enabled the internal ones.
if you're going for cheap - all the more reason to use the internal pullups - only saves a few pennies, but when you're shipping them by the truck load...
No if a pull up fails, it is a 1P repair job.
Yes if an internal pull up fails then repair it by adding an external pull up.
I've not yet seen a thread where the pullup has failed...
True it is unlikely to fail but that is what the poster asked. There are many reasons for not using the internal pull up resistors but in my opinion reliability is not one of them.
Grumpy_Mike: True it is unlikely to fail but that is what the poster asked. There are many reasons for not using the internal pull up resistors but in my opinion reliability is not one of them.
...oh no! not the great pull-up resistor debate again ;)
Don't connect Aref to 5v, just to the cap.