====== Why MSFF? ======
{{:courses:system_design:synthesis:master-slave_flip-flop:folie316_integratedcircuit.svg?nolink&700|Integrated Circuit}}

<text type="danger">integrated circuit</text> = combinational logic + storage elements

===== Master-Slave flip-flop =====
  * <text type="primary">Binary storage element: stores values 0 or 1</text>
  * **MS-FF:** <text type="primary">complete isolation/de-coupling of inputs and outputs</text>
    * 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

===== Example Moore Automaton =====
{{:courses:system_design:synthesis:master-slave_flip-flop:folie318_mooreautomaton.svg?nolink&700|Example Moore Automaton}}

output vector is a function of  state vector: <text type="danger">Y = f(S)</text>

the state vector is coded binary:

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

{{:courses:system_design:synthesis:master-slave_flip-flop:folie318_statechart.svg?nolink&300|State Chart}}

i.A. is: Number of "FF": ENTIER(log<sub>2</sub> states)

<text type="primary">#States == 2 #FF</text>

Example:
  * #States: 72
  * log<sub>2</sub>(72) = ln(72)/ln(2) = 6,1 => 7 FF
  * 2<sup>7</sup>= 128  !!!!!

<callout>
=== Notes ===
base 2 logarithm

2 power FF (number of ff)

log<sub>2</sub>(n) = ln(n)/ln(2) = log(n)/log(2)

#States: 72

log<sub>2</sub>(72) = ln(72)/ln(2) = 6,1  => 7 FF

2<sup>7</sup>= 128  !!!!!  that means :: 56 states that are not allowed, or must be additionally handled!!
</callout>