Am Samstag, 20. August 2011, 22:59:35 schrieb p4trykx:
> Hello
> As the 1-wire counter is discontinued I tried to make my own counter from
> ds2408 and 8-bit counter with bit output 74hc590.
>
The DS2408 is discontinued, too. I think the chips will be available a while
through brokers, though the price could rise. The DS2423 is hard to get
already.
(Other useful chips like the DS2409 are discontinued, too. I think it is time
to think about home-brewn replacement parts using AVR or PIC controllers.)
> I suspect that I need to add some capacitor to smooth the change form low
> to high.
>
No. The inputs of 74HC590 are *not* schmitt-trigger ones. So there is no
hysteresis, but a really tiny gap at 1/2 Vdd where the input may toggle at
high speed. To avoid this, the transition must be as fast as possible.
So either remove the RC filter (C1) from the input or better, put 1/6 40106
between the filter and the 74HC590 clock inputs. You could skip Q1, R3, R2 in
that case, too, the 40106 will do the amplifying and inversion.
>
> And another question about DS2408 behavior. Shouldn't RSTZ change it's
> state while performing read from sensed.BYTE?
>
No. RSTZ is an input. It can be used by an external circuit to switch off the
PIO outputs to avoid a "wired-or" of the input data with the current output
data.
Kind regards
Jan
------------------------------------------------------------------------------
Get a FREE DOWNLOAD! and learn more about uberSVN rich system,
user administration capabilities and model configuration. Take
the hassle out of deploying and managing Subversion and the
tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2
_______________________________________________
Owfs-developers mailing list
Owfs-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/owfs-developers
