Small System Board Microcontroller STM32 ARM Core Board.    Feature:  Kernel: ARM32 bit Cortex™-M3CPU;  Size: 22.86mm x 53.34mm;  Debug Mode: SWD;    MCU Introduction:  1. The maximum operating frequency of 72MHz;  2. Single-cycle multiply and hardware divide;  3. 64k Flash program memory;  4. 20k bytes SRAM;  5. 2.0-3.6V power supply and I / O pins;  6. On power-up, power reset (POR / PDR), programmable voltage monitor;  7. 4-16MHz crystal oscillator;  8. Embedded 8MHz RC oscillator;  9. generates CPU clock PLL;  10. Sleep Stop Standby mode;  11. VBAT power for the RTC back registers;  12. 37 Quick I / O ports, the I / O ports can be mapped to 16 external interrupts etc.    Package included:  1 x Small System Board Microcontroller STM32 ARM Core Board;  1 x Pin