74193

Discussion in 'Homework Help' started by bharani16, Apr 24, 2009.

1. bharani16 Thread Starter New Member

Apr 24, 2009
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A sequential circuit monitors the available parking spaces in a200-space parking garage and provides an indication of fullgarage by illuminating a FULL display sign and lowering theentrance gate bar .Salient features of the system are: .... A sensor at the entrance gate produces a positive 1TL pulsewhen a vehicle enters the garage.A sensor at the exit gate produces a positive 1TL pulse whena vehicle leaves the garage.The sequential circuit counts up when a vehicle enters andcounts down when the vehicle leaves the garage.The circuit produces a HIGH 1TL output when the garage isfull. This HIGH output signal is used to illuminate the Fullsign and to close the vehicle entrance gate of garage.The circuit output changes to LOW when an empty spacebecomes available in the garage. . Design and implement the sequential circuit using up/downcounters (e.g. 74193) and logic gates.

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2. StayatHomeElectronics AAC Fanatic!

Sep 25, 2008
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Do you have a question here? People are more than willing to help if you have a question but won't if you just want them to solve the entire problem.

3. bharani16 Thread Starter New Member

Apr 24, 2009
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pls check and say whether tis ckt will work..especially down counting

4. SgtWookie Expert

Jul 17, 2007
22,201
1,809
No, it won't work properly.

You're trying to clock both the LSB and MSB counters using the same input signals.

You only want the MSB counter to increment or decrement when the LSB counter outputs a carry or borrow.

5. bharani16 Thread Starter New Member

Apr 24, 2009
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can yo please explain me further

6. StayatHomeElectronics AAC Fanatic!

Sep 25, 2008
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Consider the decimal counting system, you only increment one digit at a time...

00, 01, 02, 03, ... , 09, 10

The tens digit is only incremented after you pass 9 in the ones digit. You carry the one from the addition of 9 and 1 and it ends up in the tens digit. Same for digital counters. You only want the second one to increment after the first one produces the carry.

If you increment both at the same time you get 00, 11, 22, 33, ...

7. bharani16 Thread Starter New Member

Apr 24, 2009
7
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will this ckt work if the clk inputs for msb counter is taken off..pls reply

8. bharani16 Thread Starter New Member

Apr 24, 2009
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and also other connections correct.???

9. SgtWookie Expert

Jul 17, 2007
22,201
1,809
I gave you a rather large hint with the carry/borrow output suggestion.

Can you figure out what to do with them?

We can't do your homework for you, as that would defeat the purpose of your learning exercise.

10. bharani16 Thread Starter New Member

Apr 24, 2009
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oh...your hints lead to an asynchronous counter if i am right......is there any way to do it as a synchronous counter

11. SgtWookie Expert

Jul 17, 2007
22,201
1,809
Excerpt from the TI datasheet:
"These counters were designed to be cascaded without the need for external circuitry."
Read the rest in the datasheet: