How to Use stm32f103rb: Examples, Pinouts, and Specs

The STM32F103RB is a high-performance 32-bit microcontroller developed by STMicroelectronics. It is based on the ARM Cortex-M3 core, offering a balance of processing power, energy efficiency, and rich peripheral integration. With a clock speed of up to 72 MHz, 128 KB of flash memory, and 20 KB of SRAM, the STM32F103RB is well-suited for a variety of embedded applications, including industrial automation, consumer electronics, IoT devices, and motor control systems.

• Industrial control systems
• IoT devices and smart home applications
• Motor control and robotics
• Communication gateways
• Data acquisition systems
• Consumer electronics

The STM32F103RB comes in a 64-pin LQFP package. Below is a summary of key pins and their functions:

For a complete pinout, refer to the STM32F103RB datasheet provided by STMicroelectronics.

1. Power Supply: Connect the VDD pin to a 3.3 V power source and the VSS pin to ground. Ensure the power supply is stable and within the operating voltage range (2.0 V to 3.6 V).
2. Clock Configuration: Use an external 8 MHz crystal oscillator connected to the OSC_IN and OSC_OUT pins for precise clocking. The internal PLL can multiply this frequency to achieve the desired system clock (up to 72 MHz).
3. Programming: Use an ST-Link programmer/debugger to upload firmware via the SWD (Serial Wire Debug) interface.
4. Peripherals: Configure GPIO pins and peripherals (e.g., I2C, SPI, USART) in the firmware using the STM32 HAL (Hardware Abstraction Layer) or CMSIS libraries.
5. Reset: Connect the NRST pin to a push-button for manual reset functionality.

• Decoupling Capacitors: Place 0.1 µF decoupling capacitors close to the VDD pins to reduce noise and ensure stable operation.
• Boot Mode Selection: Use the BOOT0 pin to select the boot mode (e.g., boot from flash memory or system memory for firmware updates).
• Debugging: Reserve the SWDIO and SWCLK pins for debugging and programming purposes.
• GPIO Protection: Use pull-up or pull-down resistors as needed to prevent floating inputs.

The STM32F103RB can communicate with an Arduino UNO via USART. Below is an example of STM32 code to send data over USART1:

#include "stm32f1xx_hal.h"

// Function prototypes
void SystemClock_Config(void);
void USART1_Init(void);
void USART1_Transmit(char *data);

UART_HandleTypeDef huart1;

int main(void) {
    HAL_Init(); // Initialize the HAL library
    SystemClock_Config(); // Configure the system clock
    USART1_Init(); // Initialize USART1

    char message[] = "Hello from STM32F103RB!\r\n";

    while (1) {
        USART1_Transmit(message); // Transmit message over USART1
        HAL_Delay(1000); // Wait for 1 second
    }
}

void USART1_Init(void) {
    huart1.Instance = USART1; // Select USART1
    huart1.Init.BaudRate = 9600; // Set baud rate to 9600
    huart1.Init.WordLength = UART_WORDLENGTH_8B; // 8 data bits
    huart1.Init.StopBits = UART_STOPBITS_1; // 1 stop bit
    huart1.Init.Parity = UART_PARITY_NONE; // No parity
    huart1.Init.Mode = UART_MODE_TX_RX; // Enable TX and RX
    huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE; // No flow control
    huart1.Init.OverSampling = UART_OVERSAMPLING_16; // 16x oversampling

    if (HAL_UART_Init(&huart1) != HAL_OK) {
        // Initialization error
        while (1);
    }
}

void USART1_Transmit(char *data) {
    HAL_UART_Transmit(&huart1, (uint8_t *)data, strlen(data), HAL_MAX_DELAY);
}

// System clock configuration function
void SystemClock_Config(void) {
    // Configure the system clock to 72 MHz (implementation omitted for brevity)
}

1. Microcontroller Not Responding

   • Cause: Incorrect power supply or missing decoupling capacitors.
   • Solution: Verify the power supply voltage and add 0.1 µF capacitors near the VDD pins.

2. USART Communication Fails

   • Cause: Incorrect baud rate or wiring.
   • Solution: Ensure the baud rate matches on both devices and check the TX/RX connections.

3. Cannot Program the Microcontroller

   • Cause: BOOT0 pin incorrectly configured or SWD pins in use.
   • Solution: Set BOOT0 to 0 (boot from flash) and ensure SWD pins are not used as GPIO.

4. Clock Issues

   • Cause: Incorrect crystal oscillator or PLL configuration.
   • Solution: Verify the external crystal and PLL settings in the firmware.

• Q: Can I use the STM32F103RB without an external crystal?
  A: Yes, the internal RC oscillator can be used, but it is less accurate than an external crystal.

• Q: How do I update the firmware?
  A: Use the ST-Link programmer or the built-in bootloader via USART.

• Q: What development tools are recommended?
  A: STM32CubeIDE, Keil MDK, or IAR Embedded Workbench are commonly used.

This concludes the documentation for the STM32F103RB microcontroller. For more details, refer to the official datasheet and reference manual from STMicroelectronics.