Difference between revisions of "CSC270 Exercises on FSM"
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Revision as of 11:18, 2 March 2011
--D. Thiebaut 15:24, 28 February 2011 (EST)
Exercise #1
- Implement a sequencer (FSM) which activates 3 Lights: a green light, a yellow light, and a red light. The behavior of the FSM is the following:
- the green light stays on for 30 seconds, then
- the yellow light comes on and stays on for 30 seconds, then
- the red light comes on and stays on for 30 seconds, then we repeat the pattern.
- There is only one light on at a given time.
Exercise #2
- Same as Exercise 1, but this time the behavior is the following
- the green light comes on after the red light and stays on for 30 seconds,
- the yellow light comes on and stays on for the next for 15 seconds,
- the red light comes on after the yellow light for 30 seconds.
Exercise #3
- Create a "true" frequency divider that divides by 4.
Exercise #4
- What is the state diagram of the 3-flip-flop circuit with the following equations:
D0 = Q0' D1 = Q0 XOR Q1 D2 = Q1 XOR Q2
Exercise #5
- Same question, but solve it with Python.
- flipflop.py
- implements a simple sequencer
def xor( a, b ):
if ( a==b ): return 0 return 1
def main():
# assume we start in a state where all 3 flip-flops are outputing 0 D0 = 0 D1 = 0 D2 = 0
for t in range( 20 ): Q0 = D0 Q1 = D1 Q2 = D2
if t==0: print "%2s %2s %2s %2s" % ( "t", "Q0", "Q1", "Q2" ) print "----|------------"
print "%2d %2d %2d %2d" % ( t, Q0, Q1, Q2 ) D0 = 1 - Q0 D1 = xor( Q0, Q1 ) D2 = xor( Q1, Q2 )
main()
- Output
t Q0 Q1 Q2
|------------
0 0 0 0 1 1 0 0 2 0 1 0 3 1 1 1 4 0 0 0 5 1 0 0 6 0 1 0 7 1 1 1 8 0 0 0 9 1 0 0
10 0 1 0 11 1 1 1 12 0 0 0 13 1 0 0 14 0 1 0 15 1 1 1 16 0 0 0 17 1 0 0 18 0 1 0 19 1 1 1