The STM32F103xx medium-density performance line family incorporates the high performance ARM Cortex™-M3 32-bit RISC core operating at a 72 MHz frequency, high speed embedded memories (Flash memory up to 128 Kbytes and SRAM up to 20 Kbytes), and an extensive range of enhanced I/Os and peripherals connected to two APB buses. All devices offer two 12-bit ADCs, three general purpose 16-bit timers plus one PWM timer, as well as standard and advanced  ommunication interfaces: up to two I2Cs and SPIs, three USARTs, an USB and a CAN.