STM32F103C8T6 (Blue Pill) Bare Metal Repository

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Hi! I am a beginner and trying to program the Blue Pill Module using Bare Metal (Register Programming). This repository is only meant for learning purpose. Please let me know if there is any mistake and if possible how to resolve it. For any suggestions you can connect with me on LinkedIn: Shrey Shah

Few GitHub Repositories that I referred to during development phase:

• stm32f1-baremetal
• stm32f103-1

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Description

• Basic Repository for understanding the Registers present in Blue Pill Development Module
• Created basic source files to use Registers for controlling purpose
• Projects/Template is the template which can be used as reference while creating New Project

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Repository Structure

• BareMetal: Consists of all the Register Address Mapping along with Driver Source Code
• Projects: Consists of User Specific Application
• Reference_Docs: All the Reference Documentation relevant to the topic

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STM32F103C8T6 Reference Manual

STM32F103C_Reference_Manual.pdf

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STM32F103C8T6 Pinout

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STM32F103C8T6 Features (Medium Density Device)

Specification	Details	Comments
Processor	ARM Cortex-M3	Single Core
Clock Frequency	Min: 8MHz	HSI: 8MHz
	Max: 72MHz	HSE: 8MHz
Flash	Size: 64kB	Address: 0x08000000
SRAM	Size: 20kB	Address: 0x20000000

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IRQ Details

Vector Table	76
ARM Cortex-M3 IRQ	11
STM32F103C8T6 IRQ	59
Reserved	6

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Boot Process

1. Power ON
2. Stack Pointer (SP)
   • Points to the top of SRAM (Vector Table Offset: 0x00)
3. Reset_Handler() is called
   • Vector Table Offset: 0x01
   • Initialization Steps:
     1. Copy the .data section from FLASH to SRAM
        • Note: .data refers to initialized variables.
     2. Initialize the .bss section to 0
        • Note: .bss refers to uninitialized variables.
     3. Call the Main function

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Repository Structure

STM32F103C8T6
    ├── BareMetal      # Main Bare Metal Codes
    │   ├── Core       ## Core Files: Register Structure + Debugging Configurations
    │   └── Driver     ## Driver Files: RCC, GPIO, USART, I2C, SSD1306 OLED, etc.
    ├── Projects       # User Specific Application
    │   ├── GPIO       ## GPIO Application
    │   └── Template   ## Reference Template
    ├── README.md      # Documentation
    └── Reference_Docs # Contains the Reference Documentations useful for STM32F103

Driver Structure

Driver
├── ADC
│   ├── Inc
│   │   └── adc.h
│   └── Src
│       └── adc.c
├── bare_metal.h
├── DMA
│   ├── Inc
│   │   └── dma.h
│   └── Src
│       └── dma.c
├── EXTI
│   ├── Inc
│   │   ├── exti.h
│   │   └── nvic.h
│   └── Src
│       └── exti.c
├── GPIO
│   ├── Inc
│   │   ├── gpio_config.h
│   │   └── gpio.h
│   └── Src
│       └── gpio.c
├── I2C
│   ├── Inc
│   │   ├── i2c_config.h
│   │   ├── i2c_dma.h
│   │   ├── i2c.h
│   │   └── i2c_irq.h
│   └── Src
│       ├── i2c.c
│       ├── i2c_config.c
│       ├── i2c_dma.c
│       └── i2c_irq.c
├── PWM
│   ├── Inc
│   │   ├── pwm_config.h
│   │   └── pwm.h
│   └── Src
│       ├── pwm.c
│       └── pwm_config.c
├── RCC
│   ├── Inc
│   │   ├── rcc_config.h
│   │   └── rcc.h
│   └── Src
│       ├── rcc.c
│       └── rcc_config.c
├── reg_map.h
├── SSD1306
│   ├── Inc
│   │   ├── ssd1306_font.h
│   │   └── ssd1306.h
│   └── Src
│       └── ssd1306.c
├── SysTick
│   ├── Inc
│   │   ├── systick_config.h
│   │   └── systick.h
│   └── Src
│       └── systick.c
├── Timer
│   ├── Inc
│   │   ├── timer_config.h
│   │   └── timer.h
│   └── Src
│       └── timer.c
└── USART
    ├── Inc
    │   └── usart.h
    └── Src
        └── usart.c

⚠️ Important Dependency Guideline

✅ Ensure that all dependent header files (.h) are included within the corresponding .h file, not inside the .c source file.

💡 Why?

• The build system uses the -M flag with the compiler to automatically track dependencies.
• -M only processes included headers visible through .h files at compile time
• Missing or misplaced includes (inside .c only) will break dependency resolution, leading to incomplete or incorrect builds

✔ Best Practice

• If a .c file depends on an external header, that header must be included in the corresponding .h file
• This ensures proper dependency extraction, reliable incremental builds, and fewer surprises

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Project Structure

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<Project_Name>
      ├── Inc
      │   └── main.h
      ├── Makefile
      ├── Src
      │   └── main.c
      └── Startup
          ├── stm32f1_ls.ld
          └── stm32f1_startup.c

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Makefile Basic Commands

• make all: Compiles all the relevant files and generates the executable in a "Build" Directory
• make clean: Removes the "Build" Directory
• make flash: Flashes .bin file at Flash Address (0x080000000)
• make erase_flash: Erases the Flash Memory of Blue Pill Module
• make debug: Creates the .json debug related files for Arm-Cortex Debug (VS Code) inside a .vscode directory
• make replace_makefiles: Updates all Makefiles inside "Project" directory with current Makefile
• make info: Provides information about the connected STM32 device
• make dependency: Lists the relevant files required for compilation & stores it in Build/dependency.mk for dynamic dependency tracking

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