So, here goes. I've been stubbornly googling on and off for a while and haven't found exactly what I'm looking for.
I'd like to build an Arduino-controlled constant current PSU. I need to be able to call a function within the code, such as "setCurrent(0.8);" and set the supplied current to 800mA. Simple enough, right? ><
The original way I was planning on doing this was to use a voltage regulator (LM317 comes to mind) and use a bunch of digital potentiometers wired in series-parallel (on the reference pins of the regulator) to give me the desired current setting. However, to get the current set as accurately as I want, I'll need to use something like 36 (20 - 10 - 5 - 1) pots. This is both expensive and complicated.
The maddening thing is, I have a power supply right here that is controllable via serial ("i 0.8\n"). Unfortunately, not only is it a black box - it also can't supply voltage high enough for my purposes. I believe it can supply 3V out at a maximum (I haven't looked at the specs in a while), when I need 5-6V (hence looking to a regulator like the LM317). I took it apart to see if I could glean anything, and ended up having no luck at all. I do have a list of chip part numbers, if anyone cares or thinks it might help. 
I have the code already hammered out for controlling all of those pots, but if there's a simpler solution I'd welcome any wisdom I can get. 36 digital pots feels like giving up and using duct tape.
Code I can do. Electronics... not so much. :~