Am Sonntag, 24. Dezember 2006 16:41 schrieb Japie:
> On Sun, 24 Dec 2006 14:17:18 +0200, Paul Alfille wrote:
> >> Can owfs/1wire read in mili-seconds?
> >
> > That might be pushing it.10 to 100 msec.
>
> That would do, 10.000rpm ~ 180 pulses per second, but if I take a pulse
>
> >from the cams it wil be 90 p/sec. so 10ms. will do.
>
> Is that speed limited by the sensor or the fs?
>
The speed is limited by the onewire bus system. The bitrate for adressing a
remote sensor is 16kBit, which limits sampling speed to ~10..30ms.
To count pulses, you can use the DS2423 counter chip, which gets you around
that limitation. Just sample the total amount of pulses counted by this chip
once a second, and you'll get an exact (but delayed) readout.
> >> Are there pressure sensors up to 10bar?
> >
> > Not currently, though I'm they could be built, there are voltage
> > sensors with temperature compensation.
>
> Could something be home-brew?
> There are plenty electric pressure sensors around, maybe they can be
> hoocked-up to a 1wire.
>
Yes. You can use either the voltage (e.g. DS2450) or the current sensor (e.g.
DS27xx) chips for that purpose.
> Actualy my project is similar to a weather station, only the readings are
> a bit higher but we need: rpm, temp, pressure and humidity only "abnormal"
> thing would be a way to collect data from our trothle control (100K
> potentiometer)
>
The main difference to a weather station is the sampling rate needed. Weather
in "open air" doesn't change as drastically as in intake and exhaust pipes of
an engine.
Kind regards
Jan
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