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.

FEATUREs
* ARM 32-bit Cortex™-M3 CPU Core
– 72 MHz maximum frequency, 1.25 DMIPS/MHz (Dhrystone 2.1) performance at 0 wait state memory access
– Single-cycle multiplication and hardware division

* Memories
– 64 or 128 Kbytes of Flash memory
– 20 Kbytes of SRAM

* Clock, reset and supply management
– 2.0 to 3.6 V application supply and I/Os
– POR, PDR, and programmable voltage detector (PVD)
– 4-to-16 MHz crystal oscillator
– Internal 8 MHz factory-trimmed RC
– Internal 40 kHz RC
– PLL for CPU clock
– 32 kHz oscillator for RTC with calibration