1. INTRODUCTION TO STM32 BLUE PILL

What is STM32 Blue Pill?

The STM32 Blue Pill is a low-cost development board based on STM32F103 microcontrollers.

Common Variants:

Chip	Flash	SRAM
STM32F103C6T6	32 KB	10 KB
STM32F103C8T6	64 KB	20 KB

Why STM32 over Arduino?

32-bit ARM Cortex-M3 processor
Faster clock speed (72 MHz maximum)
Professional toolchain (CubeIDE)
Industry-standard HAL/LL drivers
Used in automotive, robotics, and industrial control applications

Blue Pill Board Overview

ARM Cortex-M3 core
Peripherals: GPIO, ADC, UART, SPI, I2C, Timers
SWD debugging interface
PC13 onboard LED (typically)

2. HARDWARE CONNECTION WITH ST-LINK V2

Required Hardware

STM32 Blue Pill board
ST-LINK V2 programmer (original or clone)
Breadboard and jumper wires
USB cable

ST-LINK to Blue Pill Connections (Critical)

ST-LINK	Blue Pill
SWDIO	PA13
SWCLK	PA14
GND	GND
3.3V	3.3V (optional)
NRST	NRST (recommended)

Important: BOOT0 must be connected to GND

Power Supply Rules

Use only ONE power source at a time
Options: USB cable OR ST-LINK 3.3V output
Never apply 5V to GPIO pins

3. INSTALLING AND SETTING UP STM32CUBEIDE (v1.18)

Why CubeIDE 1.18?

Integrated CubeMX configuration tool
Integrated OpenOCD debugger
Stable STM32F1 family support
No external tools required

Installation Steps

Navigate to the STMicroelectronics website
Download STM32CubeIDE version 1.18.x
Run the installer
Launch the IDE
Select or create a workspace directory

4. STM32CUBEIDE AND CUBEMX WORKFLOW (Critical Section)

Step 1: Create New Project

File → New → STM32 Project
MCU Selection:
- If your chip is C6T6, select STM32F103C6T6
- If your chip is C8T6, select STM32F103C8T6
- DO NOT select TR or ATR variants

Step 2: Clock Configuration (Safe Setup)

RCC Configuration:

HSI: ENABLED
HSE: DISABLED
PLL: OFF (recommended for beginners)

Result: SYSCLK = 8 MHz

Rationale:

Most clone boards have unreliable crystals
HSI (internal oscillator) is more reliable

Step 3: GPIO Pinout Configuration (LED Blink Example)

Onboard LED (PC13):

Set PC13 to GPIO_Output

GPIO Settings:

Mode: Output Push Pull
Speed: Low
Pull: No pull

Step 4: SYS Settings

Navigate to System Core → SYS
Debug: Serial Wire
Disable SWV and Trace

Step 5: Generate Code

Click “Generate Code” button

LED Blink Code (Correct Implementation)

Note: PC13 is ACTIVE LOW

while (1)
{
  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET); // LED ON
  HAL_Delay(500);
  
  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_SET);   // LED OFF
  HAL_Delay(500);
}

5. FLASHING USING OPENOCD AND ST-LINK (Critical Knowledge)

Debug Configuration in CubeIDE

Debugger Settings:

Debug Probe: ST-LINK (OpenOCD)
Interface: SWD
Frequency: 400 kHz
Reset Mode: Connect under reset

Warning: High SWD speed causes erase failure

Correct Flashing Workflow

Hold RESET button on the board
Click Debug in CubeIDE
Release RESET after connection established
Click Resume
Stop debug session
Power-cycle the board

Common Errors Explained

Error	Meaning	Fix
vFlashErase packet	Target not halted	Lower SWD frequency and use connect under reset
target not halted	CPU running before erase	Lower SWD frequency and use connect under reset

6. STM32F103C6T6 vs C8T6 (Very Important)

Comparison Table

Parameter	C6T6	C8T6
Flash	32 KB	64 KB
SRAM	10 KB	20 KB

Important Rules

If you have a C6 chip, select C6 in CubeMX
Selecting C8 for a C6 chip will cause runtime faults
Many boards sold as “C8” are actually fake or mislabeled

7. STM32 WITH ARDUINO IDE

When to Use Arduino IDE

Advantages:

Quick prototyping
Familiar syntax for Arduino users

Disadvantages:

Less control over hardware
Slower execution
Less professional approach

Arduino IDE Setup

Install Arduino IDE
Add STM32 core URL to Board Manager:

https://github.com/stm32duino/BoardManagerFiles/raw/main/package_stmicroelectronics_index.json
Open Board Manager and install “STM32 MCU based boards”

Board Selection

Board: Generic STM32F103C series
Upload method: ST-Link
CPU Speed: 72 MHz (or 8 MHz for safe operation)

Arduino Blink Example

void setup() {
  pinMode(PC13, OUTPUT);
}

void loop() {
  digitalWrite(PC13, LOW);  // ON
  delay(500);
  digitalWrite(PC13, HIGH); // OFF
  delay(500);
}

8. IMPORTANT CONCEPTS

What is HAL?

Hardware Abstraction Layer (HAL) is a software layer that allows portable, readable, and maintainable code across different STM32 microcontrollers.

What is OpenOCD?

Open On-Chip Debugger is an open-source debug server that:

Communicates with ST-LINK hardware
Interfaces with GDB debugger
Halts the CPU
Erases flash memory
Programs flash memory

Why “Software Reset”?

Prevents CPU from executing corrupted code
Allows flash erase operations
Mandatory for STM32F1 series

Difference: RUN vs DEBUG Mode

Mode	Meaning
RUN	Standalone firmware execution
DEBUG	MCU halted and inspectable by debugger

End of Tutorial

📘 COMPLETE STM32 BLUE PILL TUTORIAL