Lecture21

# Lecture21 - 0 again • Design this counter using JK-ﬂip ﬂops • Also add an output Y which is equal to “1” when the counter is counting

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ENSC150 Lecture 2 1 Agenda More Sequential Design Binary Counter with Load Option BCD Counter 1/6 Lecture 21 Atousa Hajshirmohammadi, SFU

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Counter w/ Load We want to add to the binary counter developed in Lecture 19 the capability to load the counter with an initial binary number. For example, we want to be able to force the state of the counter to go to the value “6” when we want. This is the counter we have developed so far: Q 3 Enable with Binary Counter EN Clk Q 0 Q 1 Q 2 Now we want D 0 Enable with Binary Counter EN Q 0 Q 1 Q 2 Q 3 and Load Clk Load D 2 D 3 D 1 Operation: If “Load = 1”, Load D 0 ,D 1 ,D 2 ,D 3 to the output of the counter, regardless of the value of “EN”. If ”Load = 0”, then EN con- trols the operation of t h e counter like before. 2/6 Lecture 21 Atousa Hajshirmohammadi, SFU
Counter w/ Load (Cont.) clk Q C D EN Q 0 Q C D EN Q 1 Q C D EN Q 2 Q C D EN Q 3 A B S C Half Adder A B S C Half Adder A B S C Half Adder A B S C Half Adder MUX I 1 I 0 Y MUX I 1 I 0 Y MUX I 1 I 0 Y MUX I 1 I 0 Y 3/6 Lecture 21 Atousa Hajshirmohammadi, SFU

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BCD Counter BCD Counter is a 4-bit counter that counts from “0” to “9” and back to

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Unformatted text preview: 0 again. • Design this counter using JK-ﬂip ﬂops • Also, add an output Y, which is equal to “1” when the counter is counting the number “9”. 1 J K Q J K Q ( t ) 1 ¯ Q ( t ) JK-FF Q ( t + 1) 1 1 1 4/6 Lecture 21 Atousa Hajshirmohammadi, SFU BCD (State Table) Present State Next State Q 3 Q 2 Q 1 Q Q 3 ( J 3 ,K 3 ) Q 2 ( J 2 ,K 2 ) Q 1 ( J 1 ,K 1 ) Q ( J ,K ) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 5/6 Lecture 21 Atousa Hajshirmohammadi, SFU BCD (Optimization) We need to ﬁnd J 3 ,K 3 ,J 2 ,K 2 ,J 1 ,K 1 ,J ,K in terms of Q 3 ,Q 2 ,Q 1 ,Q , and implement the circuit. For example: J 3 6/6 Lecture 21 Atousa Hajshirmohammadi, SFU...
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## This note was uploaded on 04/16/2009 for the course ENSC 150 taught by Professor Dr.atousahashirmohammadi during the Spring '09 term at Simon Fraser.

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Lecture21 - 0 again • Design this counter using JK-ﬂip ﬂops • Also add an output Y which is equal to “1” when the counter is counting

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