STM32F100 (ARM Cortex-M3) Hardware Driver Library & Reference in C

A production-grade, modular open-source C hardware library and educational reference suite targeting the STM32F100 (ARM Cortex-M3) microcontroller family (e.g., STM32VLDISCOVERY board, STM32F100RB/CB Value Line).

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⚡ Key Features

• Modular Architecture: Clean separation of Driver Headers (include/), Implementations (src/), System & Startup Files (system/), and Modular Examples (examples/).
• Bare-Metal Drivers: Hand-crafted peripheral abstractions for:
  • RCC: Reset and Clock Control & Peripheral Clock Gating
  • GPIO: Pin configuration (CRL/CRH), atomic pin operations (BSRR/BRR), state toggles & reads
  • USART: Polled transmission & Interrupt-driven RX/TX with a lock-free Circular Ring Buffer
  • SysTick: ARM Cortex-M core timer for sub-millisecond precision (delay_ms(), millis())
  • TIM3 PWM: General-purpose timer duty cycle modulation for LED breathing/dimming
  • EXTI Interrupts: Hardware pin interrupts (PA0 Button mapped to EXTI0_IRQHandler)
  • ADC1: 12-bit Analog-to-Digital single-channel voltage sampling
• Dual-Execution Support: Compiles both locally on Host Machines (CLI Simulation mode via gcc/clang) and natively for Bare-Metal ARM Cortex-M3 targets (arm-none-eabi-gcc).

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📂 Repository Layout

Hardware-programming-C/
├── README.md                           # Master open-source repository documentation
├── Makefile                            # Multi-target build script
├── LICENSE                             # Apache 2.0 Open Source License
├── include/                            # Driver Header Interfaces
│   ├── stm32f100_map.h                 # Master Register Maps & Physical Address definitions
│   ├── stm32f100_rcc.h                 # Reset & Clock Control API
│   ├── stm32f100_gpio.h                # GPIO Driver API (CRL/CRH, BSRR/BRR)
│   ├── stm32f100_usart.h               # USART API & Lock-Free Ring Buffer
│   ├── stm32f100_systick.h             # SysTick 1ms Timekeeping API
│   ├── stm32f100_timer.h               # TIM3 Hardware PWM API
│   ├── stm32f100_exti.h                # External Pin Interrupt API
│   └── stm32f100_adc.h                 # ADC1 12-Bit Voltage Sampling API
├── src/                                # Core Driver Implementations
│   ├── stm32f100_rcc.c                 # APB1/APB2 clock enablement
│   ├── stm32f100_gpio.c                # Pin configuration & atomic manipulation
│   ├── stm32f100_usart.c              # Serial stream & ring buffer routines
│   ├── stm32f100_systick.c            # SysTick tick generator & precision delays
│   ├── stm32f100_timer.c              # Timer prescaler & PWM compare setup
│   ├── stm32f100_exti.c               # AFIO line mapping & EXTI line triggers
│   └── stm32f100_adc.c                # ADC conversion sequence setup
├── system/                             # Bare-Metal ARM System & Linker Files
│   ├── startup_stm32f100.c             # Vector Table & Reset_Handler (.data / .bss initialization)
│   ├── stm32f100.ld                    # Linker Script (128KB Flash @ 0x08000000, 8KB RAM @ 0x20000000)
│   └── host_sim.c                      # Host CLI simulation register storage
└── examples/                           # Modular Educational Reference Examples
    ├── 00_hello_world/                 # GPIO LED Blink & USART Serial Transmission
    ├── 01_systick_delay/               # Non-blocking SysTick Timekeeping (`millis()`)
    ├── 02_gpio_interrupt_exti/         # Hardware Pin Interrupt (`EXTI0_IRQHandler`)
    ├── 03_usart_interrupt_ringbuf/      # Interrupt-Driven Serial RX/TX with Circular Buffer
    ├── 04_timer_pwm_dimmer/            # TIM3 Hardware PWM LED Breathing/Dimming
    └── 05_adc_potentiometer/           # ADC1 12-Bit Analog Voltage Sampling

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🚀 Quick Start

1. Build and Run All Examples (Host Terminal Simulation)

To compile and execute all 6 modular reference examples directly on your host machine:

# Build and run all modular examples
make run

# Clean build binaries
make clean

2. Cross-Compile for Bare-Metal ARM Target

To build bare-metal .elf binaries and raw .bin images for physical STM32F100 hardware targets using arm-none-eabi-gcc:

make arm

Generates target binary images in the repository root:

• bin_arm_00_hello_world.bin
• bin_arm_01_systick_delay.bin
• bin_arm_02_gpio_interrupt_exti.bin
• bin_arm_03_usart_interrupt_ringbuf.bin
• bin_arm_04_timer_pwm_dimmer.bin
• bin_arm_05_adc_potentiometer.bin

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📚 Peripheral Driver Reference

1. GPIO Configuration & Atomic Control (include/stm32f100_gpio.h)

/* Configure PC9 as General Purpose Output Push-Pull 2MHz */
gpio_config_pin(GPIOC, 9, GPIO_MODE_OUTPUT_PP_2MHZ);

/* Atomic Pin Set / Reset using BSRR and BRR */
gpio_write_pin(GPIOC, 9, true);  /* High (LED ON) */
gpio_write_pin(GPIOC, 9, false); /* Low (LED OFF) */
gpio_toggle_pin(GPIOC, 9);        /* Toggle ODR bit */

2. SysTick Precision Delay (include/stm32f100_systick.h)

/* Initialize 1ms tick generator @ 8MHz System Clock */
systick_init(8000000);

/* Non-blocking timing check */
if ((millis() - last_time) >= 250) {
    last_time = millis();
    gpio_toggle_pin(GPIOC, 9);
}

/* Blocking millisecond delay */
delay_ms(100);

3. USART Ring Buffer Serial Driver (include/stm32f100_usart.h)

/* Initialize USART1 with Interrupt RX & Ring Buffer @ 115200 Baud */
usart1_init_interrupt(115200, 8000000);

/* Send string */
usart1_send_string("Hello, STM32F100!\r\n");

/* Read bytes from circular ring buffer */
uint8_t byte;
if (ring_buffer_get(&g_usart1_rx_ringbuf, &byte)) {
    /* Process incoming character */
}

4. Hardware Timer PWM Modulation (include/stm32f100_timer.h)

/* Configure TIM3 Channel 4 for 1 kHz PWM output on PC9 */
timer3_init_pwm(1000, 8000000);
timer3_start();

/* Set Duty Cycle (0% to 100%) */
timer3_set_duty_cycle(4, 75);

5. Hardware Pin Interrupts (include/stm32f100_exti.h)

/* Map PA0 (User Button) to EXTI Line 0 on Rising Edge */
exti_config_pin(EXTI_PORT_A, 0, EXTI_TRIGGER_RISING);

/* Interrupt Handler */
void EXTI0_IRQHandler(void) {
    if (exti_is_pending(0)) {
        exti_clear_pending(0);
        /* Handle pin interrupt */
    }
}

6. Analog-to-Digital Sampling (include/stm32f100_adc.h)

/* Initialize 12-bit ADC1 on PA1 (Channel 1) */
adc1_init();

/* Read 12-bit value (0..4095) */
uint16_t raw_adc = adc1_read_channel(1);
uint32_t millivolts = (raw_adc * 3300UL) / 4095UL;

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🛠️ Bare-Metal Memory Map (Cortex-M3 Vector Table)

When booting on target hardware, the ARM Cortex-M3 core reads physical memory starting at 0x08000000:

Memory Address   Vector Content
-----------------------------------------------------------
0x08000000       Initial Stack Pointer (_estack = 0x20002000)
0x08000004       Reset_Handler Pointer
0x08000008       NMI_Handler Pointer
0x0800000C       HardFault_Handler Pointer
...              ...
0x0800003C       SysTick_Handler Pointer
0x08000058       EXTI0_IRQHandler Pointer
0x080000D4       USART1_IRQHandler Pointer

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📄 License

Distributed under the Apache License 2.0. See LICENSE for full details.