This week I designed (and ordered) two encoders built around the LDC1101, one is linear and one is rotary. Rather than try and integrate everything with an MCU at this stage, I went ahead and just broke out all of the necessary communication pins, similar to my last board, but this time with the LC tank fully integrated. Not a whole lot to say here until the boards come in and I can test them. In the meantime I have been searching for a suitable ADC replacement for the HX711 back over on the dynamometer project. It would be great to have an infrastructure for high resolution + gain analog signal measurement for a number of projects, this one included potentially.
I machined three rotors to test with, one is a single sided PCB with equal sized copper and copperless targets for sensing, the other is the same targets but with full copper on the back of the PCB (it's 1.6mm and I am imagining the copper on the back might be useful as shielding for outside noise in some applications). The third has 10% smaller copper target area, which might be helpful considering the coil's flux path is much larger than just the immediate area in front of the coil, and the smaller copper area might result in greater deltas between Rp_max and Rp_min.
The image below links to a video of the target mounted with under 10um of perpindicularity error between the target and the motor's rotational axis (that's 5/10's per division on the indicator). 10um is very measurable for the LDC1101, but due to the nature of the encoder it should be cancelled out for the most part. After I get some initial data I will deliberately push it out of perpindicularity and see how sensitive we are to that spec, but for now I am trying to have everything optimally dialed in.
