25MHz high-speed crystal oscillator and 32.768KHz low-speed crystal oscillator. The V3.0 version adopts a lead-free process, featuring a gold-plated pin header for enhanced environmental friendliness. Flash pads have been reserved, and FATFFS routines are available for USBDisk. The WeAct FW Bootloader is pre-installed at the factory as a special testing version; hex files are not provided. Supports MicroPython programming with available firmware; refer to configuration files, but technical support is not offered. Boards with versions V1.3 and above include 3 buttons: reset button, BOOT0 button, and user buttons. Entering ISP mode: 1: Press and hold the BOOT0 button and the reset button while powered on, release the reset button first, then release the BOOT0 button after 0.5 seconds. 2: Hold the BOOT0 button while powered off, then release it 0.5 seconds after powering on. DFU mode: connect to a computer via a data cable; if unrecognized, you can gently heat the chip (25 degrees Celsius) and re-enter ISP mode. Serial port mode: use USB to serial port to connect PA9 and PA10 of the core board. WeAct FW Bootloader: no USB to serial port or debugger required; just a TYPE-C data cable is needed to complete the firmware download. Press and hold the KEY button, click the reset button until LED C13 flashes, then release the KEY button to enter. Model: STM32F401CEU6 Color: Black Material: PCB Package Contents: 2 * Development Boards with pins Only the above package contents are included; other products are not included. Note: Light reflection and different displays may cause the item��s color in the picture to slightly differ from the real product. Measurement allowed error is +/- 1-3cm.