Date: 2017-Week-39
Status: Working.

STM32F103 - Working with the USART on the free EmBitz IDE in Windows. Basics STM32-BluePill board (STM32F103C8T6)

Introduction:

Getting started with the STM32-Blue Pill generic board using the free EmBitz IDE on Windows.
To work with the USART.
Done using the Standard Peripheral Library, no HAL drivers were used.

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Information about the STM32-BluePill:

• STM32F103C8T6 microcontroller, 64KB Flash memory, 20KB SRAM in 48-pin LQFP, 4 to 16 Mhz crystal input to generate maximum 72Mhz clock
• SWD programming/Debugging interface.
• One User LED - Green _ PC13
• On-Board 8Mhz Crystal.
• On-Board 32.786Khz oscillator connected to RTC ports.
• Extension header for all QFP48 I/Os for quick connection for prototyping.

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Useful Links:

Example on Github

Gypsyengineer.com - STM32 USART sending text commands

stm32duino - Blue Pill Official
Pinout Diagram
ST Microelectronics STM32 ARM MCU Site
STM32 Info @ emcu

A template project for STM32 on Linux
Limit the current – take care of your favorite LED
GETTING STARTED WITH STM32 ARM CORTEX-M3 USING GCC (STM32F103, NUCLEO-F103RB)
LED Resistor Calculator

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I did the following to get the clock working correctly at 56Mhz using the 8MHz external crystal:

system_stm32f10x.c = System Clock Configuration file.
We are using the external oscillator (HSE) which is 8Mhz
We are using PLLCLK Mux

Setup In stm32f10x.h:

1. Uncomment the line: #define USE_STDPERIPH_DRIVER
2. set this: #define HSE_VALUE ((uint32_t)8000000)
3. set this: #define HSI_VALUE ((uint32_t)8000000)

Setup In system_stm32f10x.c:

1. Uncomment the 56MHz clock config line and comment the 72MHz line as seen below:

   /* #define SYSCLK_FREQ_HSE    HSE_VALUE */
   /* #define SYSCLK_FREQ_24MHz  24000000 */
   /* #define SYSCLK_FREQ_36MHz  36000000 */
   /* #define SYSCLK_FREQ_48MHz  48000000 */
   #define SYSCLK_FREQ_56MHz  56000000
   //#define SYSCLK_FREQ_72MHz  72000000

The rest of the file will do the configuration automatically to get the following:

• PLLCLK = enabled
• PLLMul = x7
• SYSCLK = 56MHz
• AHBPrescaler = /1
• HCLK = 56Mhz
• APB1Prescaler = /2
• PCLK1 = 28Mhz
• APB2Prescaler = /1
• PCLK2 = 56Mhz

Setup In fm_stm32F1_delay.c:

1. fac_us=SystemCoreClock/8000000;