[Ronja] Twister2 U63-U65

Daniel Schneider schneider2000 at web.de
Mon Apr 7 23:22:26 BST 2008


Karel Kulhavy schrieb:
> ---- Sordrag at gmx.de schrieb:
>   
>> Hi all!
>>
>> I'm trying to understand how the Twister works. My problem is the cascade of U63 to U65 (and also the one of U51 and U53). I don't get the idea behind this. I already read the FAQs but they were not enough.
>>     
>
> The idea is that if a fast signal is pulse extended then the individual pulses blur
> together and create a steady level. If a slow one is pulse extended they don't blur
> and stay as a frequency.
>
>   
>> Can anyone explaine me in detail how the identification of data in the signal by the use of the cascades works?
>>     
>
> U54 is just a buffer. C66 and R52 replace leading edges in the signal with short
> H impulses and everything else with L. U52 inverts it and on every leading edge of the
> original signal, U63 gets reset to zeroes on all outputs. On every tick of the 16MHz clock (62.5 ns) one tap
> gets set to one. That means if the output is on the 5th tap, it gets set from
> 0 back to 1 after 4-5 ticks, that means after 250-312.5 ns it gets back to H.
>
> If the incoming signal has the leading edge pitch less than 250ns, then the output stays
> permanently in 0. If it has more, then it will contain ones interspersed with zeroes.
>
> The Manchester signal has maximum leading edge pitch of 200ns. The silence between
> the packets takes at least 9600ns. So packets will produce zero on U63-10 and the interframe gaps one.
>
> The problem is link integrity pulses will trigger a false packet alarm. Therefore U64 and U65 are there to clean this out.
>
>
>
>   
Hi Clock,

I also was wondering about how the filtering of the link integrity pulse 
works. Can you explain this a little bit more detailed. I don't get it 
with the timing.

thx


>> And why is there the OR (U54) before this cascade? It just works as an inverter and the signal gets inverted back thru U52. Is this necessary?
>>
>> And why are there after the RX discriminator (U51, U53) those two Schmitt Triggers of U52. I think if I do the hole cicuit on a PCB I have short wires so those Triggers aren't necessary!?
>>     
>
> The Schmitt trigger inverters are there to invert the signal. Their Schmitt function
> is unused.
>
> CL<
>   
>> Thx for your help.
>>
>> Greetz Sord
>>
>>
>> -- 
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>>
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>>     
>
>
>   





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