Ultra-small size, basically the same as Arduino Nano, can be directly plugged into the breadboard without taking up much space

Leads out all GPIO interfaces

Onboard a reset button, a BOOT0 selection button, and a user-available button

One user available LED light

Reserve an external crystal oscillator interface. You can choose whether to use it through the jumper.

Micro-USB interface with 500mA overcurrent protection

External ST-Link debugging interface

Crystal oscillator jumper description: By default, this jumper is disconnected,

the crystal oscillator is not connected, and the ports (PF0, PF1) can be used as ordinary IO ports.

After short-circuiting this jumper with an electric soldering iron, the crystal oscillator is normally connected,

and the external crystal oscillator can be configured in the program normally.

The user LED is connected to PB3, and the high level lights up.

When the BOOT0 button is pressed, the BOOT0 pin will be connected to VCC.

At this time, power on will automatically enter the ISP programming mode.

The user button is connected to the PA0 port, and PA0 is connected to VCC when pressed.

This setting can be used to wake up the microcontroller when it enters sleep mode. Simultaneously,

This button is connected in parallel with a 0.1uF debounce capacitor, so PA0 cannot output high frequency signals.

If you want to output high frequency signals on PA0, please find capacitor C7 on the back and remove it.