I've reverse engineered the part of seek circuit that is connected to sensor pins.
Big thanks to Mike for giving us images of layers (
http://goo.gl/r2n1d5).
Sensor pins:
Elements on the other side of pcb:
(Color of the trace shows the same voltage potential; green dots are common ground):
Scheme:
(I've made an error with pin description. 13 and 15 are GND not NC...)
And not all capacitors are 1nF... some are some are not...
The only lines going to mcu (
http://goo.gl/D8B8ML) are:
- pin 8 goes to J2 and J4 (general IO)
- pin 9 goes to K2 (general IO)
- pin 12 goes to K3 (clock)
Pin 14 is most likely analog input which reads voltage on diode.
As Mike already came to conclusion this diode acts as a thermal sensor for sensor temperature.