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cdcnitw
Joined: 12 Oct 2007
Posts: 8
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 11 Nov 2008 14:42 how can i detect the last edge in a switching digital signal |
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please help me how to detect a last edge in a switching digital signal;
say if i have a digital signal as follows
initially low level(0)
starts switching depending on some other signal with random freq(0101010101....)
the stops at high level (1) after some period
i need to detect the last edge of this switching signal
please help me how to do it
thanks
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omara007
Joined: 06 Jan 2003
Posts: 1283
Helped: 39
Location: Dubai
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11 Nov 2008 14:49 how can i detect the last edge in a switching digital signal |
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If you are expecting to have a final value of '1' for example, you can design a counter that counts clock cycles during '1' .. if the counter, say, reaches a specific large value like 10 or 20 (as you decide), then you can consider the circuit is no more switching and this '1' is the final value ..
same if the final value is expected to be zero ..
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cdcnitw
Joined: 12 Oct 2007
Posts: 8
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12 Nov 2008 6:02 Re: how can i detect the last edge in a switching digital si |
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thanks omara
but i need the time at which the last edge occurs...
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omara007
Joined: 06 Jan 2003
Posts: 1283
Helped: 39
Location: Dubai
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12 Nov 2008 10:58 how can i detect the last edge in a switching digital signal |
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you need to have a condition for the last edge .. how will you know that it's the last edge unless you monitor it for some time and you notice that it doesn't change !! ..
If you are going to do so, then you can easily know the time at which the last edge occurs by translating the counter counts (or the number of clock cycles involved) into time .. as easy as this.
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