added code for A2

.idea/misc.xml

src/A2/CMakeLists.txt

src/A2/encoder.c

src/A2/encoder.h

src/A2/i2c.c

src/A2/i2c.h

src/A2/main.c

src/A2/pwm.c

src/A2/pwm.h

src/A2/smart_knob.c

src/A2/smart_knob.h