STM32F103VBT6 ARM-based 32-bit MCU with Flash, USB, CAN, seven 16-bit timers, two ADCs and nine communication interfaces.

Y5250H 2029 K8QEZ. This is quite possibly the gyroscope, but we won't be able to tell for sure without decapping the chip.

Kionix KXSC4 10227 2410 accelerometer

Texas Instruments BQ24080 1-cell Li-Ion Charger.

A little birdy helped us identify this TPS63030 High Efficient Single Inductor Buck-Boost Converter.

CSR (Cambridge Silicon Radio) BC4RE A16U Bluetooth transmitter

AKM AK8974 three-axis Electronic Compass (MEMS)