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Old 03-14-2010, 12:02 AM
rkobasketball rkobasketball is offline
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Question 3 bit Synchronous Up Down Counter that automatically counts up and down

Hello everyone,
I am in need of some extra help
I have made an UP/DOWN binary synchronous counter that works with a switch that has a logic 1 for up counting and a logic 0 for down counting. The next part of this assignment is to make the counter switch from up to down automatically. This means that it will count
0, 1, 2, 3, 4, 5, 6, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2... (all in binary of course).
I am 95% sure that I am going to need another J-K Flip Flop (74112) and at least 2 AND or NAND gates. If you do not feel like telling me all the information, just tell me what extra gates/inverters/flip-flops I need.
Thanks so much in advance!
-Julian Molina-Goni
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Old 03-14-2010, 12:38 AM
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beenthere beenthere is offline
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Take a look at a 74190 up/down counter.
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Old 03-14-2010, 12:42 AM
rkobasketball rkobasketball is offline
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Default Sorry for not mentioning restrictions

Sorry for not being specific, I can only use 74112, LS08, LS32, LS04, and maybe some NAND gates
Nothing else
hope this helps
-Julian Molina-Goni
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Old 03-14-2010, 12:58 AM
k7elp60 k7elp60 is offline
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You may want to look at the 4510 or the 4516 CMOS counters. They are 4 bit but they can preset to divide by 8. They have carry in and carry out terminals and the up/down count is by logic level on the U/D terminal. All these features may make it easier to do what you want.
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Old 03-14-2010, 01:04 AM
rkobasketball rkobasketball is offline
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I am a high school junior, so I don't grasp full knowledge of CMOS and all of that.
I can only use +5v chips and I am not sure about the difference between CMOS TTL etc.
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Old 03-14-2010, 01:38 AM
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You can get the data sheet for a 74190 and look at the internal logic to see how to arrange a counter to do up/down counting and so on.
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Old 03-14-2010, 03:46 AM
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BMorse BMorse is offline
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check this site out, it might give you some help with what you need to get done, it covers AND,NAND and other gates including JK and RS flip flops.. >>> http://www.doctronics.co.uk/4011.htm#bistable


Or think about using a full adder circuit such as this one >> http://isweb.redwoods.cc.ca.us/instr...logic/full.htm

B. Morse
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