Inductive Proximity Sensor

I've done simple example how to design inductive proximity sensor with 1" printed coil, CortexM0 chip, 2 diodes, 2 resistors and 1 cap. Schematics (STM32F050), oscillograms, explanation and source code (for Keil µVision) provided:

http://cortexdev.blogspot.com/2015/01/inductive-proximity-sensor.html

Any suggestions would be appreciable!