PI-detector with asymmetrical auto tuning balance of ground

[sevzirfo]

My version PI metal the detector on the microcontroller AT90S2313-10 with asymmetrical auto tuning of balance of ground. Feature of the circuit - always working slow auto tuning of balance of ground, which allows to work always on the maximal sensitivity in a static mode. The feature of auto tuning - asymmetry, at detection of metal under the coil works SLOW auto tuning, at absence of metal under the coil - FAST auto tuning (restoration). The parity(ratio) SLOW / FAST - 1/5. HEX code for the microcontroller can be found here -http://sevzirfo.narod.ru/skif_auto.rar