[sdiy] moog module designs

[Scott Gravenhorst]

ASSI <Stromeko at Compuserve.DE> wrote:
>Hi Tim, Scott,
>
>On Samstag, 23. April 2005 20:11, Scott Gravenhorst wrote:
>> Looking at this again, I disagree that this truth table correctly
>> shows what happens with J and K both high.  if X means "don't care",
>> then the table is ambiguous.  i.e., for J=H and K=X, what of X is
>> high? then J=H, K=H and Q=H.  Now look at J=X and K=H.  If X is H,
>> then J=H and K=H and then Q is LOW?  That conflicts with the first
>> statement.
>
>you are losing me here. Just write out the X explicitly as H and L and 
>keep the lines with J and K both high:
>
>J	K	Q 	-> 	Q	Q'
>
>H	H	L		H	L
>H	H	H		L	H

Yeah, I get this, but you're _adding_ a dependancy on Q that is not
present in the ST Micro datasheet.  It has input columns for J and K and
an output column (so labeled) for Q.  Philips describes this behavior
better IMHO by doing it on one line as:

inputs     output
J  K       Q
-----------------
H  H       not Q



>When J and K are both H (and S and R both L), then the next output 
>depends only on the previous Q, more specifically it toggles.
>
>> Thats what bit me. If J is high the IC doesn't care what K is at, its
>> going to put a high out the Q output.
>
>No, it's going to put out Q'.

I don't read it that way, it doesn't cite the dependancy on Q.  Philips
does by stating that Q = invert Q after the clock edge.  So to me, the
ST truth table is ambiguous.  I'm looking at the PDF right now, I don't
see any indication that one should consider J, K _and_ Q as 3 input
logical expression.


>> This means that I'll have to expand my lab IC notebook to include
>> datasheets for multiple versions of standard parts. And my wife
>> wonders why I don't want to work electronics proffesionally anymore.
>
>The datasheet is correct and the truth table expands to a normal JK 
>flip-flop.
>
>On Samstag, 23. April 2005 19:17, Scott Gravenhorst wrote:
>> Thanks again, I looked at their data sheet, the internal schematic
>> isn't even close to the Philips sheet.
>
>They use a transfer gate D-FF instead of the RS-FF that you seem to 
>expect, which isn't exactly uncommon in CMOS. This leads to the input 
>circuitry shown in the data sheet (check any textbook for the 
>transformations between different FF types).
>
>> The ST Micro abortion has a 
>> J-K input circuit that cannot possibly ever consider the logic state
>> of both J and K inputs being high.
>
>It can. Whatever was wrong with the '4027 that Tim used it, wasn't the 
>data sheet. I'd suspect the culprit with the setup and hold times if 
>the problem is specific to the ST part.

Ok, I get this, my problem is of a semantic nature with the way the
truth table is presented.  It is my contention that the data sheet
should be indicating a dependancy on Q and it clearly does not say that.
 It works only when you know enough to assume the dependancy on Q and I
think that's righteously lame.


>
>Achim.
>-- 
>+<[Q+ Matrix-12 WAVE#46 Neuron microQkb Andromeda XTk sonic heaven]>+
>
>Factory and User Sound Singles for Waldorf Q, microQ and rackAttack:
>http://Stromeko.Synth.net/#WaldorfSounds
>

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