CSC270 GYRSequencer.py

--D. Thiebaut 10:48, 2 March 2012 (EST)

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This program shows how programming can be used to check if the equations found for a sequencer actually make the system work as advertised.

See this page for additional examples of how to create logic operators in python.

Python V2.X

# GYRSequencer.py
# D. Thiebaut
# A very quick and dirty way to check a sequencer...
# This sequencer activates a G, Y, and R light system
# s.t. G is on for 2 cycles, followed by Y for 1 cycle
# followed by R for 1 cycle.  Then the whole cycle repeats

Q1 = 0
Q2 = 0

def NOT( a ):
    return 1 - a

for step in range( 20 ):

    # the Q1 and Q2 outputs go through combinational logic to generate the new values
    # of D1, D2, and the outputs G, Y, R...
    D1 = Q1 ^ Q2     # xor
    D2 = NOT(  Q2 )
    G  = Q1
    Y  = NOT ( Q1 | Q2 )
    R = NOT ( G | Y )

    # show the stable circuit signals
    print "Q1Q2 = %d %d  | GYR = %d %d %d" % ( Q1, Q2, G, Y, R )

    # wait for the next clock tick (the user presses Enter)
    raw_input( "> " )

    # as soon as the clock has ticked, D1 and D2 get latched in the flipflops
    # and Q1 and Q2 reflect the values captured.
    Q1 = D1
    Q2 = D2

Python V3.X

# GYRSequencer.py
# D. Thiebaut
# A very quick and dirty way to check a sequencer...
# This sequencer activates a G, Y, and R light system
# s.t. G is on for 2 cycles, followed by Y for 1 cycle
# followed by R for 1 cycle.  Then the whole cycle repeats

Q1 = 0
Q2 = 0

def NOT( a ):
    return 1 - a

for step in range( 20 ):

    # the Q1 and Q2 outputs go through combinational logic to generate the new values
    # of D1, D2, and the outputs G, Y, R...
    D1 = Q1 ^ Q2     # xor
    D2 = NOT(  Q2 )
    G  = Q1
    Y  = NOT ( Q1 | Q2 )
    R = NOT ( G | Y )

    # show the stable circuit signals
    print( "Q1Q2 = %d %d  | GYR = %d %d %d" % ( Q1, Q2, G, Y, R ) )

    # wait for the next clock tick (the user presses Enter)
    input( "> " )

    # as soon as the clock has ticked, D1 and D2 get latched in the flipflops
    # and Q1 and Q2 reflect the values captured.
    Q1 = D1
    Q2 = D2