STM32F103R board is a simple and easy development board to learn STM32 microcontroller programming. Its heart is STM32F103RBT6 ARM Cortex-M3 microcontroller with 128K of Flash and 20K of SRAM memory. It can be clocked at maximum 72MHz frequency and is considered to be a medium-density performance line microcontroller. Other features include USB, CAN, 7 timers, 2ADCs and 9 communication interfaces. Development board has several nice features to get started with. First of all it has RS232 interface for communicating and accessing bootloader. There also is a USB 2.0 full speed interface connector that also can work as power supply. Next is a JTAG connector to program microcontroller using tools like J-Link adapter. Two push buttons and two progammable LEDs are hardwired to MCU pins alongside all I/Os connectors.