.. _stm32f401_mini:

STM32 Mini F401
###############

Overview
********

The STM32 Mini F401 is an extremely low cost and bare-bones
development board featuring the STM32F401CC, see `STM32F401CC website`_.
More info about the board with schematics available `here <stm32-base-board-page_>`_

.. image:: img/STM32_Mini_F401-1.jpg
      :align: center
      :alt: STM32 Mini F401

Hardware
********

The STM32F401CC based board provides the following
hardware components:

- STM32F401CCU6 in UFQFPN48 package
- ARM |reg| 32-bit Cortex |reg| -M4 CPU with FPU
- 84 MHz max CPU frequency
- VDD from 1.7 V to 3.6 V
- 256 KB Flash
- 64 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 (4)
- 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 stm32f401_mini 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 the defconfig file:

        ``boards/arm/stm32f401_mini/stm32f401_mini_defconfig``

Default Zephyr Peripheral Mapping:
----------------------------------

- UART_1 TX/RX : PA9/PA10
- I2C1 SCL/SDA : PB8/PB9
- SPI1 CS/SCK/MISO/MOSI : PA4/PA5/PA6/PA7
- PWM_4_CH1 : PB6
- PWM_4_CH2 : PB7
- ADC_1 : PA1
- SW0 : PB2 (routed to BOOT1 dip switch)
- LED0 : PC13

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.

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, which on this board
is a dip switch.

Flashing
========

Installing dfu-util
-------------------

It is recommended to use at least v0.8 of `dfu-util`_. 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`_.

Flashing an Application
-----------------------

Connect a USB-C cable and the board should power ON. Force the board into DFU mode
by setting the BOOT0 dip switch position to ON. Reset the board with the NRST button.

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

.. zephyr-app-commands::
   :zephyr-app: samples/basic/blinky
   :board: stm32f401_mini
   :goals: build 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
**********

.. target-notes::

.. _Zadig:
   https://zadig.akeo.ie/

.. _stm32-base-board-page:
   https://stm32-base.org/boards/STM32F401CCU6-STM32-Mini-F401

.. _dfu-util:
   http://dfu-util.sourceforge.net/build.html

.. _STM32F401CC website:
   https://www.st.com/en/microcontrollers-microprocessors/stm32f401cc.html