So, I've noticed a great many ICs have some aspect of their respective programming accomplished by a resistor to ground from the Programming Pin.

I've seen this in battery charger ICs, variable output LDOs, and tons of other chips.

I'm still at the beginner level - so what I was wondering is how could one set up a circuit so the user could choose the resistor? Let's say for argument's sake that we're selecting the output current of a battery charger. Let's also say that I want the user to have two options, ergo Resistor A and Resistor B.

I know that I could use an spdt switch, but how could I do this electronically, say from an MCU? I thought of using two NPN BJTs as switches, with each base driven by a GPIO pin and the requisite current-limiting base resistor, switching the resistor's path to Ground.

I also thought about a digital potentiometer...

But then I thought that there must be a better way, and I was curious what you awesome genius folks would have to say on the matter.

While we're at it, what if I gave the user, say, 5 choices?

TIA, and I'm looking forward to learning more, every day, with a little help from youz guyz...