sentence: c24x : 16 bit , fixed point , 20 to 40 mhz c28x : 32 bit , fixed or floating point , 100 to 150 mhz stellaris ( rebranded as tiva in 2013 ) arm cortex-m3 based 32-bit mcu family hercules : transportation and industrial safety mcu 's based on the cortex-r4f and cortex-m3 in the past , ti has also sold microcontrollers based on arm7 ( tms470 ) and 8051 cores .