Date: 2017-Week-38
Status: Working.

Blink the LED when User Button is pressed on the STM32 NUCLEO-F411RE board (STM32F411RET6)

Introduction:

Getting started with the STM32 NUCLEO-F411RE board using the free EmBitz IDE on Windows.
To blink the LED when the User Button is pressed.
Based on [this article](./User Manuals/isildak_en.pdf) and used this article to get it working.
Flashed firmware hex file using ST-Link Utility.

I did the following to get the clock working correctly:

system_stm32f4xx.c - System Clock Configuration file.
We are using the internal oscillator (HSI) which is 16Mhz
We are using PLLCLK Mux

Setup In stm32f4xx.h:

1. Uncomment the line: #define USE_STDPERIPH_DRIVER
2. set this: #define HSE_VALUE ((uint32_t)16000000)
3. set this: #define HSI_VALUE ((uint32_t)16000000)

Setup In system_stm32f4xx.c:

1. #define PLL_M 16
2. #define PLL_N 336
3. #define PLL_P 4
4. #define PLL_Q 7
5. uint32_t SystemCoreClock = 84000000;

Setup In fm_stm32F4_delay.c:

1. fac_us=SystemCoreClock/16000000;

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Cannot connect to device: "old st-link firmware/st-link already used"

First time I thought that the problem was caused by a brief short-circuit caused by hot-plugging the SIM. This was not the cause. After some research, I found out that I was setting PA14 as output and high, and SWDIO is connected to this pin. This is why there were those problems, and why "Connect under reset" worked, and why the problem went away after erasing the flash.

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Useful Links:

https://os.mbed.com/platforms/ST-Nucleo-F411RE/ STM32F411RE microcontroller
Nucleo board
SDK changes log
Limitations
Good Info on board
Nucleo boards Information *Good
Automatic Sliding Gate Example
Main site for cool links and info
ST Youtube channel
STM32F4-Library explanation and usage
Clock setup