St stm32 32 bit flash arm cortex m microcontrollers st stm32f103zet6 the stm32f103zet6 is a performance line high density 32 bit arm based microcontroller with 512 kbytes of flash memory and a cpu frequency of 72mhz the microcontroller incorporates the high performance arm cortex m3 risc core and utilises an extensive range of enhanced peripherals and ios connected to two apb buses standard communication interfaces and multiple timers further enhance the usability of this microcontroller