I'd like to learn how to, efficiently, use Arduino outputs and i'd like to use one Arduino's output to do more things than just one.
I don't need anything complicated, just some voltage control.
How can I easily achieve it?
PS. What I want to do in this project is to be able to have 3.3V, 4V, 5V, 6V and 9V outputs to control 12V fans. I want to do this by using several different voltage regulators and I want to use just one Arduino output to switch between each voltage regulator. I might use MOSFETs too, not sure yet. Any suggestions very welcome.
I don't want PWM at this moment.
It looks plausible, although that example illustrates that you need three pins to control the shift register, so in your particular example, you're only saving a couple of pins. For an exercise for learning about shift registers though, why not - the shifted pins can control a relay or mosfet to switch the appropriate voltage to the fan.
several different voltage regulators and I want to use just one Arduino output to switch between each voltage regulator
All that control with just 1 pin is a bit of an ask.
If you are happy to sequence through the regs it's not too hard, but if you want to skip from say reg 1 to reg3 without selecting reg 2 then some cleverness would be required.
Ok, maybe when I say one I wouldn't mind using more, say 3, but I'd like those 3 pins to do more than just 3 things, if you know what I mean
I think my original plan has been changed to just two or three voltage regulators so in this case it won't be so bad. However if I wanted to use 3 pins to do say 5 things, would this be possible?
I need a number of pins for LCD screen to work.
Is there a possibility to link two or more arduino boards?