I know, an R2R ladder is made of resistors. But its purpose is to allow a stepped range of voltages (not resistances) to be produced at one output from only two input voltages, inserted at multiple points.
I'm trying to produce a variable resistor that can achieve 6 bit linear resolution (as opposed to log or some other curve - I want to slide up and down a ramp of resistance). My available method of doing this is to tie any point in a resistor array or network to a common rail (using a microcontroller to switch the GPIOs between inputs and outputs and then go to sleep). The terminals of this device, across which resistance would be measured don't have to be connected to that bus. I'd consider using other components but I'm assuming that resistors are what's needed.
I have looked online, looked for electronic decade resistors, looked in The Art of Electronics and it doesn't seem to have been done. But intuitively it seems like it should be possible.
Can anyone please give me some ideas about whether this is possible and where to look next?