Nathan, I have found the solution. It’s the specific Dual MC33926 board I’m using. You answered a very similar question two years ago: Current sensing on dual MC33926 motor driver shield for Arduino: low values
I HIGHLY suggest that Pololu include this specific information in the spec sheet for that board and not just the chip itself; there a good chunk of researchers and hobbyists running these motors at low current draw and trying to use current sensing for control! Unless I missed it somewhere, but I did due diligence and read everything about the current sensing I could in the spec sheet for the board.
So I’m now at a crossroads. We’ve been grappling with trying to get experiments set for months now. We have the Arduino code perfected to work with that shield and library in particular and I am under a time crunch. I would prefer not to replace it with an entirely new shield and go through the fun of learning new libraries, specs, etc. You suggested this in that thread two years ago: https://www.pololu.com/category/118/current-sensors
My question is: could I directly integrate these with my current setup as is, a dual MC33926 stacked on top of an Arduino? I would like to continue using the MC33926 board for distributing power supply to the motors. From a quick read, it appears I can insert the sensors anywhere along the current path and they can be powered by the 3.3V Arduino Vout if I used the ACS711EX . This fits the motors running at 3-12V with almost certainly less than 1A of current. My plan at the moment (because my head is still swimming from the idea I might have to switch hardware) is to stack two of these on the free pins of the Arduino/33926 stack, but I’m unsure if I have the free pins to do it. I believe the output is analog, and therefore I could use the A2-5 pins which are not used by the motor shield. Or, and this is a bit more devious, could I snip the connections at A0 and A1 between arduino and motor board, route the hall effect sensor outputs to those Arduino pins, and use the native library functions with the more accurate current sensor?
Any insight you can offer regarding an inline current sensor such as this for my project would be immensely helpful. Again, Arduino Uno with dual MC33926, running a 14V input with 3-12V range on the HP12V 75:1 motors (due to speed variation), encoder readings, and a need to sense current to determine torque for mechanical power.
Or, I could perhaps use the ACS724(https://www.pololu.com/product/4041) because it has much better resolution, but requires 5v from the arduino. I thought the 5V output could handle two of these (max 14 mA) and the two motor encoders (10mA max) but it appears that 20mA is already pushing it.
What do you suggest I do? My instinct at this point is to search for the best possible resolution current sensor which can be powered by the 3.3V output for 3-12V and 0-2A range, because I’d prefer not to mess with adding any more hardware than I need to. Thanks for slogging through all of this.