/**
@defgroup    boards_weact-f401cc WeAct-F401CC board
@ingroup     boards
@brief       Support for the WeAct-F401CC Board

## Overview

WeAct-F401CC is a board with the same form-factor as the blue/blackpill,
but with an STM32F401CCU6 and a USB-C connector.

It is available on sites like AliExpress for less than 3€.

## Hardware

![WeAct-F401CC](https://user-images.githubusercontent.com/1301112/69389644-eb5fb080-0ccc-11ea-8002-67d3db851250.png)

### MCU
| MCU              | STM32F401CCU6         |
|:---------------- |:--------------------- |
| Family           | ARM Cortex-M4F        |
| Vendor           | ST Microelectronics   |
| RAM              |  64KiB                |
| Flash            | 256KiB                |
| Frequency        | up to 84MHz           |
| FPU              | yes                   |
| Timers           | 8 (2x watchdog, 1 SysTick, 6x 16-bit)    |
| ADCs             | 1x 12-bit             |
| UARTs            | 3                     |
| SPIs             | 4                     |
| I2Cs             | 3                     |
| RTC              | 1                     |
| Vcc              | 2.0V - 3.6V           |
| Datasheet        | [Datasheet](https://www.st.com/resource/en/datasheet/stm32f401cc.pdf) |
| Reference Manual | [Reference Manual](https://www.st.com/content/ccc/resource/technical/document/reference_manual/9b/53/39/1c/f7/01/4a/79/DM00119316.pdf/files/DM00119316.pdf/jcr:content/translations/en.DM00119316.pdf) |

## Implementation Status

| Device            | ID            | Supported                 | Comments                                                  |
|:----------------- |:------------- |:------------------------- |:--------------------------------------------------------- |
| MCU               | STM32F401CC   | partly                    | Energy saving modes not fully utilized                    |
| Low-level driver  | GPIO          | yes                       |                                                           |
|                   | PWM           | yes (4 pins available))   |                                                           |
|                   | UART          | 2 UARTs                   | USART2 via  PA3(RX)/PA2(TX), USART1 on PA10(RX)/PA9(TX)   |
|                   | I2C           | 1 I2C                     |                                                           |
|                   | SPI           | 1 SPI                     |                                                           |
|                   | USB           | yes                       |                                                           |
|                   | Timer         | 1 32 bit timer (TIM5)     |                                                           |

## Flashing the device
The device comes with a bootloader that allows flashing via `dfu-util`.

If RIOT is already running on the board, you can upload your RIOT-firmware by typing

```
make BOARD=weact-f401cc flash
```

RIOT will make sure to enter the bootloader automatically.

If RIOT crashed or you have the plain board with the stock firmware, you have to enter
the bootloader manually.

There are two buttons on the board labeled `BOOT0` and `NRST`.

 - Hold down `BOOT0`
 - Shortly press `NRST` to reset the CPU while keeping `BOOT0` held down

The board will now show up as `0483:df11` - `STM32 BOOTLOADER` and will accept
firmware using the DFU protocol.

*Note:* You need to have write permissions to the device.
On Linux you could add yourself to the `plugdev` group and store the following as `/etc/udev/rules.d/99-weact-f401cc.rules`:

```
SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="df11", GROUP="plugdev", MODE="660"
```

## UART

stdio is provided through USB CDC ACM so the board can be used
without any extra hardware, save for a USB-C cable.

 */