Why MSFF?

integrated circuit = combinational logic + storage elements

• Binary storage element: stores values 0 or 1
• MS-FF: complete isolation/de-coupling of inputs and outputs
  • input value is buffered and transfered to the output
  • the inputs are locked
  • two static latches (or gated, transparent)
  • locked/controlled by complementary clock.
• MS-FF: basic storage element for ASIC/IC/FPGA design
  • applications for MS-FF: state machine (counter, shift registers, controllers) further is:
    • FF : master-slave FF
    • Latch : transparent, bistable multivibrator/flipflop

output vector is a function of state vector: Y = f(S)

the state vector is coded binary:

subtype STATE is bit_vector (1 downto 0);
constant START    : STATE  := “00” ;
constant MIDDLE   : STATE  := “01” ;
constant STOP     : STATE  := “10” ;

i.A. is: Number of “FF”: ENTIER(log₂ states)

#States == 2 #FF

Example:

• #States: 72
• log₂(72) = ln(72)/ln(2) = 6,1 ⇒ 7 FF
• 2⁷= 128 !!!!!