Mystery Programmable Brushless ESC, 40 A SBEC (ordered from http://www.hobbyking.com/).

AVR8 pin map

Signal Pin
UH 26
UL 12
VH 28
VL 27
WH 2
WL 9
BAT (A2) 25
USTAR (A0) 23
VSTAR (A7) 22
WSTAR (A6) 19
+5V 4, 6, 18
GND 3, 5, 21

Sensorless Commutation

Mystery controller with assigned part numbers

Mystery controller sensorless commutation circuit diagram