The USB port is powered by 5V, and the pin can be powered by 3.3V 5V. STM32F103C8T6 development board information: Core: ARM 32-bit Cortexx-M3 CPU High 72MHz operating frequency Single cycle multiplication and hardware division Memory:From 64K or 128K bytes of Flash program memory Up to 20K bytes of Clock, reset and power management 2.0-3.6V power supply and I or O pins Power-on or power-off reset (POR or ), programmable voltage monitoring Low power consumption:Sleep, shutdown and standby modes V BAT powers the and backup registers 2 12-bit analog-to-digital converters, 1us conversion time (up to 16 Conversion range: 0 to 3.6V,Dual sample and hold function,temperature sensor) DMA:7-channel DMA controller,Peripherals supported: , ADC, SPI, I 2 C andUSART,Up to 80 fast I or O ports,26 or 37 or 51 or 80 I or O ports, all I or O ports can be mapped to,16 external interrupts almost all ports are 5V tolerant Debug mode:Serial Single Wire Debug (SWD) and JTAG interface Up to 7 ,3 16-bit , each with up to 4 for Channels for input capture or output compare or PWM or pulse count and incremental encoder input,1 16-bit with deadband control and emergency for motor Controlled PWM Advanced Control ,2 watchdog ( and windowed) System time : 24-bit self-decrementing counter Up to 9 communication interfaces Up to 2 I 2 C interfaces (supports SMBus or PMBus) Up to 3 USART interfaces (support ISO7816 interface, , IrDA interface and modem control) Up to 2 SPI interfaces (18Mbitsc) CAN interface (2.0B active) USB 2.0 interface calculation unit, 96-bit chip code Colour: black Material: ABSandmetal Size: 5x3x0.2cm Package Contents: 1 x Motherboard (send pin headers but not solder) Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is 1-3cm.