STM32F105xx Connectivity Line MCUs The STM32F105xx connectivity line microcontrollers incorporate the high-performance Arm® Cortex®-M3 32-bit RISC core operating at a 72 MHz frequency, high-speed embedded memories (Flash memory up to 256 Kbytes and SRAM up to 64 Kbytes), and an extensive range of enhanced I/Os and peripherals connected to two APB buses. All devices offer two 12-bit ADCs, four general-purpose 16-bit timers plus a PWM timer, as well as standard and advanced communication interfaces: up to two I2Cs, three SPIs, two I2Ss, five USARTs, a USB OTG FS, and two CANs.