Some resources to help you getting started with STM32 programming.
The 2N3906 is a common PNP bipolar junction transistor used for general purpose low-power amplifying or switching applications. Compared to the general run of silicon transistors, it is designed for low current and power and medium voltage, and can operate at moderately high speeds. The type was registered by Motorola Semiconductor in the mid-sixties, together with the complementary NPN type 2N3904. It has a plastic TO-92 case.
When looking at the flat side with the wires pointed downward, the three wires emerging from the transistor are (left to right) the emitter, base, and collector leads.