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- Joined
- Jan 21, 2010
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- 25,510
I am using digital fundamental 9th edition from Floyd
I'll see if I can locate a copy somewhere. I'm not promising.
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- Jan 21, 2010
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- 25,510
You are remarkably lucky. I was able to borrow a copy...
You first need to read and understand section 1-2, starting on p6 in my copy. The core stuff is on pages 6 and 7. Make sure you understand them.
Figure 1-5 is really important, but at the moment, concentrating on the waveforms is sufficient as we're not really concerned about aspects which deal with noise margin (although you should understand that too)
Having got that far, you should understand where rising and falling edges are.
Then you should skim through chapter 7, pp 371 to 382. Some of this may be beyond what you currently understand, but you should concentrate on the parts where they define the basic action of a flipflop (figure 7.3 is good if pictures help you). Then note section 7.2 when it talks about edge triggering. Note the relationship this generates with the timing of the flip-flop's reaction to inputs compared with the clock (p 738).
Now, consider that the 555 is generating clock pulses. Note that the waveform matches in all significant aspects those in figure 1-6 (p 7). Now you realise that parts of that waveform are rising and falling edges.
From chapter 7 you realise the importance of rising and falling edges to edge-triggered flip-flops.
The 4017 consists of 5 edge triggered flip-flops and some decoding logic to get the 10 outputs (and they're not really important just yet)
So now you know that it is the edges (and specifically the rising edge in your case -- read the datasheet) of the clock pulses (from the 555) that cause the 4017's flip-flops to react to their input states.
If you look at the arrangement of flip-flops in the 4017 (it's a twisted ring, or johnson counter) then you can deduce that it has 10 states (for 5 flip-flops) and that the outputs of each flip-flop feed into the input of the next. The action of each clock pulse (the rising edge) is to move it from the current state to the next. (edit: deducing the function of the counter is quite a bit of hard work, you may be able to just take my word and that of the datasheet that it eventually results in the outputs following the pattern as described)
Once you know all of this, you have either answered your question, or you understand enough to re-word it in a way that makes sense.
You first need to read and understand section 1-2, starting on p6 in my copy. The core stuff is on pages 6 and 7. Make sure you understand them.
Figure 1-5 is really important, but at the moment, concentrating on the waveforms is sufficient as we're not really concerned about aspects which deal with noise margin (although you should understand that too)
Having got that far, you should understand where rising and falling edges are.
Then you should skim through chapter 7, pp 371 to 382. Some of this may be beyond what you currently understand, but you should concentrate on the parts where they define the basic action of a flipflop (figure 7.3 is good if pictures help you). Then note section 7.2 when it talks about edge triggering. Note the relationship this generates with the timing of the flip-flop's reaction to inputs compared with the clock (p 738).
Now, consider that the 555 is generating clock pulses. Note that the waveform matches in all significant aspects those in figure 1-6 (p 7). Now you realise that parts of that waveform are rising and falling edges.
From chapter 7 you realise the importance of rising and falling edges to edge-triggered flip-flops.
The 4017 consists of 5 edge triggered flip-flops and some decoding logic to get the 10 outputs (and they're not really important just yet)
So now you know that it is the edges (and specifically the rising edge in your case -- read the datasheet) of the clock pulses (from the 555) that cause the 4017's flip-flops to react to their input states.
If you look at the arrangement of flip-flops in the 4017 (it's a twisted ring, or johnson counter) then you can deduce that it has 10 states (for 5 flip-flops) and that the outputs of each flip-flop feed into the input of the next. The action of each clock pulse (the rising edge) is to move it from the current state to the next. (edit: deducing the function of the counter is quite a bit of hard work, you may be able to just take my word and that of the datasheet that it eventually results in the outputs following the pattern as described)
Once you know all of this, you have either answered your question, or you understand enough to re-word it in a way that makes sense.
Last edited:
Where is the copy of the book ?
- Joined
- Jan 21, 2010
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- 25,510
Sitting on my desk as home.
- Joined
- Jan 21, 2010
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- 25,510
As long as your power supply is an appropriate voltage you should be able to leave it running indefinitely. I'm not even going to comment on the current capacity of your power supply because this circuit draws so little.
then how can i refer ?
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- Jan 21, 2010
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- 25,510
Because YOU said it was the text you're using.
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