Agreed - internal comparator was apparently not part of the low-energy plan. It is out.
Cleverness - Thanks smajdalf!
Noted thanks - I am just as concerned with the point brought up by ShermanP below about the IDE. Arduino and the universe of handy libraries is essential for generalists, such as myself.
Great ideas, a reed switch consumes no power. however in my project, constraints related to resolution, cost, and space... along with the need to use commodity components, make that difficult. BTW - Pulolu makes a motor encoder that appears to be similar in nature to what you are describing.
Pulolu's magnetic encoder.
Do you know of a rotary encoder design that has a near-zero quiescent draw that can toggle a TTL line in response to angular displacement? Such a device would surely be in demand.
I see your point, but it is the switched detent that is the sticking point. The angular resolution I am after, in a package with a diameter of about 20mm, is about .5 degree. At the circumference, if expressed linearly, that would be an inner-detent switch spacing of .08mm (.003"). We are getting the upper realm of thin film deposition, photolithography, etc...
I need to do a deep dive on that. As I mentioned above the Arduino-univeres libraries are an important aid, and accelerator to the development process.
Thanks again to everyone who commented!
Dan
San Jose, CA