SV: Re: SV: Re: [sdiy] Camel*ont* soft Da synth!

[Scott Gravenhorst]

Magnus Danielson <cfmd at bredband.net> wrote:
>From: karl dalen <dalenkarl at yahoo.se>
>Subject: SV: Re: SV: Re: [sdiy] Camel*ont* soft Da synth!
>Date: Thu, 4 May 2006 00:00:41 +0200 (CEST)
>Message-ID: <20060503220041.84670.qmail at web25510.mail.ukl.yahoo.com>
>
>> 
>> --- Magnus Danielson <cfmd at bredband.net> skrev:
>> 
>> > From: karl dalen <dalenkarl at yahoo.se>
>> > Subject: SV: Re: [sdiy] Camel*ont* soft Da synth!
>> > Date: Wed, 3 May 2006 23:31:38 +0200 (CEST)
>> > Message-ID: <20060503213138.73231.qmail at web25510.mail.ukl.yahoo.com>
>> > 
>> > > 
>> > > --- Paul Maddox <P.Maddox at signal.QinetiQ.com> skrev:

[trimmed]

>> Right, and no baud rate clock either! 
>
>Ah... that is *almost* right, I will actually agree with you since there is no
>_REAL_ baud rate clock thing which would make it directly usefull, but you can
>actually change the clock division from /1, /16 and /64. Woopie! Three baud-
>rates programmable!
>
>> Holy crap!

Some trivia:

3 baud rates yes, but these are not equal internally.  These divide ratios actually control
the number of times each bit is sampled.  AFAIR, it works like this: for /16, the bit is
sampled 16 times.  The sample is then sent to a counter (which is reset to zero at the start
of each bit), if a sample is high (or one) then the counter is clocked once.  If it's zero it
is not clocked.  At the end of the 16 counts (or 1 or 64 depending on the setting) the high
bit of the counter (I think it's a 3 bit counter for /16) is the bit that is shifted into the
output register.  This has the effect of suppressing noise, more than 1/2 of the bits have to
be a one for the output to be a one.  For /64, the same thing happens, but there are more bits
in the counter.  With /1, there is no counter, so this is the least noise immune and /64 is
the best.  In a very quiet system, these can be used as different baud rates, but if you want
high noise immunity, you need to use the /64 and crank up the clock freq.


Pardon me if this is trivia that everyone knows...



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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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