The STM32F401CCU6 Development Board WeAct V3.0 (commonly known as the WeAct "BlackPill") is a high-performance, compact 32-bit ARM Cortex-M4 development board engineered for embedded computing, robotics control, DSP processing, and real-time IoT prototyping. Powered by the STMicroelectronics STM32F401CCU6 microcontroller operating at up to 84 MHz, it integrates a hardware single-precision Floating Point Unit (FPU), digital signal processing (DSP) instructions, and 256 KB of high-speed embedded flash memory. Built with high-quality hardware upgrades in the WeAct V3.0 revision—including a USB Type-C interface, dual onboard crystal oscillators, dedicated boot/reset tactile switches, and an unpopulated SOIC-8 footprint for external SPI flash expansion—it serves as a low-cost, drop-in computing upgrade over traditional 8-bit boards and entry-level STM32F103 "BluePill" modules.

Specifications

• Board Model / Revision: WeAct Studio STM32F401 Core Board (Version 3.0 / BlackPill)
• Primary Microcontroller: STMicroelectronics STM32F401CCU6
• Processor Architecture: 32-bit ARM Cortex-M4 with Hardware FPU (Single-Precision) & DSP Instruction Set
• Maximum CPU Core Clock Frequency: 84 MHz
• Embedded Flash Memory: 256 KB
• Internal SRAM: 64 KB
• External Memory Expansion: Onboard unpopulated SOIC-8 pad for SPI NOR Flash (supports W25Q32, W25Q64, W25Q128)
• Operating Logic Voltage: 3.3 V DC
• Input Voltage Limits:
  • Via USB Type-C: 5.0 V DC (Regulated down via onboard ultra-low-dropout 3.3V LDO)
  • Via 5V Pin: 4.8 V to 5.5 V DC
  • Via 3V3 Pin: 3.0 V to 3.6 V DC (Direct regulated input)
• I/O & Peripherals:
  • Total General Purpose I/O (GPIO): Up to 36 accessible pins (Most are 5V-tolerant)
  • Analog-to-Digital Converter (ADC): 1 × 12-bit SAR ADC (Up to 16 external channels / 2.4 MSPS)
  • Timers: Up to 11 timers (Advanced control, 16-bit, and 32-bit general-purpose PWM timers)
  • Communication Interfaces: 3 × USART/UART, 3 × I2C, 4 × SPI (with multiplexed I2S for high-end audio)
  • USB OTG: 1 × USB 2.0 Full-Speed On-The-Go (FS OTG 12 Mbps) interface supported natively by hardware
• Crystals & Clock Sources:
  • High-Speed External (HSE): 25 MHz High-Precision Passive Quartz Crystal
  • Low-Speed External (LSE): 32.768 kHz RTC Quartz Crystal (for internal real-time clock calibration)
• User Interface & Controls:
  • Tactile Switches: Reset Button (NRST), Boot Mode Selector (BOOT0), and User Programmable Key (KEY / PA0)
  • LED Indicators: 1 × Power LED (PWR - Red), 1 × User Status LED (LED - Blue, connected to PC13)
• Debug & Programming Interface:
  • Standard 4-Pin SWD Header (3V3, SWDIO/PA13, SWCLK/PA14, GND) for ST-Link / J-Link / DAPLink
  • Native USB DFU Bootloader support via BOOT0 button
• Form Factor & Pin Pitch: Dual-in-Line 40-Pin DIP layout with standard 2.54 mm (0.1") pitch (Breadboard compatible)
• PCB Dimensions: Approx. 53.0 mm × 20.8 mm (L × W)
• Net Weight: Approx. 6.0 g (without headers soldered)

Features

• Hardware FPU & DSP Math Acceleration: Cortex-M4 core computes floating-point math, trigonometric calculations, PID loops, and digital filtering in single clock cycles, vastly outperforming Cortex-M3 (F103) devices.
• Modern USB Type-C Connector: Features a durable USB-C receptacle for firmware flashing, virtual COM port telemetry, and power input, complete with CC pull-down resistors for seamless compatibility with C-to-C cables.
• Dual Factory Oscillators: Includes a 25 MHz main oscillator for accurate USB bus clock generation (48 MHz PLL branch) and a 32.768 kHz RTC crystal for precise timekeeping in low-power sleep modes.
• Built-in DFU ROM Bootloader: Easily flashed via standard USB-C cable without needing an external programmer by holding BOOT0 on power-up.
• Unpopulated SPI Flash Footprint: Solder pads on the underside of the PCB allow adding an external 4MB–16MB SPI flash IC for storing MicroPython scripts, font libraries, audio waveforms, or sensor logs.
• Wide Software Ecosystem: Supported by STM32CubeIDE, Keil MDK, PlatformIO, Arduino IDE (via STM32duino core), MicroPython, and CircuitPython.

Common Applications

• Robotics & Flight Controllers: Multi-axis drone flight stabilization, inverse kinematics for hexapods/robotic arms, and high-frequency brushless motor field-oriented control (FOC).
• Custom USB Human Interface Devices (HID): Building custom mechanical keyboards, macro pads, flight simulator rudder pedals, and low-latency gaming peripherals.
• Digital Audio Synthesizers & DSP Filters: Real-time I2S audio decoding, wave synthesis, graphic equalizer processing, and acoustic spectrum analyzers.
• Data Acquisition & High-Speed Telemetry: High-sample-rate oscilloscope probes, logic analyzers, vibration analysis nodes, and CAN bus industrial gateways.
• Smart IoT & Wearable Nodes: Compact edge computing devices executing local machine learning inferencing (TinyML) and sensor fusion algorithms.

Usage Tips

• Flashing via Native USB (DFU Mode):
  • You do not need an external ST-Link programmer to upload code. Hold down the BOOT0 button, tap the NRST (Reset) button once, and release BOOT0 to drop the chip into the internal ST factory DFU bootloader.
  • Upload binary or hex files directly using STM32CubeProgrammer, dfu-util, or the Arduino IDE / PlatformIO upload utility set to "DFU" mode.
• Arduino IDE Configuration (STM32duino):
  • Install the "STM32 MCU Based Boards" package via the Arduino Boards Manager.
  • Under the Tools menu, set:
    • Board: "Generic STM32F4 series"
    • Board part number: "BlackPill F401CC"
    • U(S)ART support: "Enabled (generic 'Serial')"
    • USB support (if using serial prints over USB): "CDC (generic 'Serial' supersede U(S)ART)"
    • Upload method: "STM32CubeProgrammer (DFU)" or "SWD" (if using ST-Link)
• SWD Debug Header Wiring:
  • When using an external ST-Link V2 programmer, connect the 4-pin SWD header located at the tail end: 3V3 → 3.3V, GND → GND, SWDIO → SWDIO, SWCLK → SWCLK.
  • Do NOT power the board through both the USB Type-C port and the ST-Link 3.3V/5V pins simultaneously, as this can back-feed current into your computer's USB controller and damage the LDO regulator.
• 5V Tolerance Considerations:
  • While the majority of STM32F401 GPIO pins are 5V-tolerant (marked "FT" in the datasheet), pins configured in analog mode (ADC inputs) or true open-drain without clamping are limited strictly to 3.6V max.
  • Always double-check the pin table before connecting 5V TTL sensors to analog ADC pins (PA0–PA7, PB0–PB1).
• Breadboard Soldering Alignment: Insert the included 20-pin dual male header strips into a solderless breadboard first, set the PCB on top, and solder the pins while seated. This ensures the pins stay perpendicular and line up with breadboard sockets.