25 MHz high-speed crystal oscillator and 32.768 kHz, 6 pF low-speed crystal oscillator. Version V3.0 uses lead-free manufacturing process. Pin headers are gold-plated. Flash pads are reserved. USBDisk and FATFS routines are included. WeAct HID FW Bootloader is pre-programmed at the factory. This is a factory test version; HEX files are not provided. Supports MicroPython programming. Compatible MicroPython firmware is available; configuration files are provided via link. Technical support is not offered. Boards from version V1.3 and later include three buttons: reset, BOOT0, and user button. Entering ISP mode: Method 1: Press and hold BOOT0 and reset buttons while powering on. Release reset first, then release BOOT0 after 0.5 seconds. Method 2: Hold BOOT0 while power is off, then release BOOT0 0.5 seconds after powering on. DFU mode: Connect to a computer using a USB-C cable. If unrecognized, gently warm the chip (to ~25°C) and retry ISP mode. Serial port mode: Use a USB-to-serial adapter connected to PA9 and PA10. WeAct HID FW Bootloader: No USB-to-serial adapter, debugger, or driver required—firmware download is done via USB-C cable only. To enter bootloader mode: Press and hold the user button, press reset, wait for LED C13 to flash, then release the user button. Microcontroller: STM32F411CEU6 / STM32F401CEU6 Color: Black Material: Plastic Package includes: 1 × Development Board Note: Actual product color may vary slightly due to lighting and display differences. Dimensional tolerance: ±1–3 cm.