Black Pill V3.0

Overview

The WeAct Black Pill V3.0 Board is an extremely low cost and bare-bones development board featuring the STM32F401CE, see STM32F401CE website [6]. This is the 48-pin variant of the STM32F401x series, see STM32F401x reference manual [7]. More info about the board available here [4] and on WeAct Github [3].

Hardware

The STM32F401CE based Black Pill V3.0+ Board provides the following hardware components:

  • STM32F401CEU6 in UFQFPN48 package

  • ARM® 32-bit Cortex® -M4 CPU with FPU

  • 84 MHz max CPU frequency

  • VDD from 1.7 V to 3.6 V

  • 512 KB Flash

  • 96 KB SRAM

  • GPIO with external interrupt capability

  • 1x12-bit, 2.4 MSPS ADC with 16 channels

  • DMA Controller

  • Up to 11 Timers (six 16-bit, two 32-bit, two watchdog timers and a SysTick timer)

  • USART/UART (3)

  • I2C (3)

  • SPI/I2S (5)

  • SDIO

  • USB 2.0 full-speed device/host/OTG controller with on-chip PHY

  • CRC calculation unit

  • 96-bit unique ID

  • RTC

Supported Features

The Zephyr blackpill_f401ce board configuration supports the following hardware features:

Interface

Controller

Driver/Component

NVIC

on-chip

nested vector interrupt controller

SYSTICK

on-chip

system clock

UART

on-chip

serial port

GPIO

on-chip

gpio

PINMUX

on-chip

pinmux

FLASH

on-chip

flash

SPI

on-chip

spi

I2C

on-chip

i2c

ADC

on-chip

ADC Controller

USB OTG FS

on-chip

USB device

The default configuration can be found in boards/weact/blackpill_f401ce/blackpill_f401ce_defconfig

Pin Mapping

Available pins:

Black Pill V3.0+ Pinout

Default Zephyr Peripheral Mapping:

  • UART_1 TX/RX : PA9/PA10

  • I2C1 SCL/SDA : PB8/PB9

  • SPI1 CS/SCK/MISO/MOSI : PA4/PA5/PA6/PA7 (Routed to footprint for external flash)

  • PWM_4_CH1 : PB6

  • PWM_4_CH2 : PB7

  • ADC_1 : PA1

  • USER_PB : PA0

  • USER_LED : PC13

Note on SPI pin mapping: According to the board release notes [1], there was a brief change for V2.0 specifically where MISO was routed to PB4 for the flash footprint. This was reverted for V2.1+ so that the flash DO pin was routed back to PA6. If using V2.0 and en external flash, the pinmux will need to be modified accordingly.

Clock Sources

The board has two external oscillators. The frequency of the slow clock (LSE) is 32.768 kHz. The frequency of the main clock (HSE) is 25 MHz.

The default configuration sources the system clock from the PLL, which is derived from HSE, and is set at 84MHz, which is the maximum possible frequency to achieve a stable USB clock (42MHz).

Programming and Debugging

There are 2 main entry points for flashing STM32F4X SoCs, one using the ROM bootloader, and another by using the SWD debug port (which requires additional hardware). Flashing using the ROM bootloader requires a special activation pattern, which can be triggered by using the BOOT0 pin.

Flashing

Installing dfu-util

It is recommended to use at least v0.8 of dfu-util [5]. The package available in debian/ubuntu can be quite old, so you might have to build dfu-util from source.

There is also a Windows version which works, but you may have to install the right USB drivers with a tool like Zadig [2].

Flashing an Application

Connect a USB-C cable and the board should power ON. Force the board into DFU mode by keeping the BOOT0 switch pressed while pressing and releasing the NRST switch.

The dfu-util runner is supported on this board and so a sample can be built and tested easily.

# From the root of the zephyr repository
west build -b blackpill_f401ce samples/basic/blinky
west flash

Debugging

The board can be debugged by installing the included 100 mil (0.1 inch) header, and attaching an SWD debugger to the 3V3 (3.3V), GND, SCK, and DIO pins on that header.

References