Resolver Angular Sensor With Encoder and SPI Outputs.

This is all concept.  No hardware yet. 

A sine wave is generated using the 12 bit CDAC with a lookup table that is periodically sent on an interrupt.  The output is then smoothed, amplified and converted to AC.  Although the steps in a 12 bit converter are fine, the smoothing filter may be required since the final output to the resolver is basically an inductor and any fast transition may show up.  The linear audio amplifier should be able to provide 3 watts of power.  Hopefully the output Sine wave will not deform but that may depend on the size of the resolver excitation hardware.  A sense line feedback is provided to the micro for analysis and calibration.  By using a PIC32MK, up to 6 simultaneous 12 bit ADC reading can be captured during peak AC transition periods.  Currently only 4 are being used.  There may be a small lagging phase shift introduced from the smoothing filter and the actual resolver hardware.  To take this into account, the excitation feedback and the sensory information can be separated into 2 sampling interval times.  A calibration may be required for the hardware portion.  The smoothing delay should be a fixed delay once it is tuned for the desirable frequency. (1-10khz).  Once the values are acquired, the instantaneous position can be calculated filtered and outputted as a QEI and SPI output.