Hi,

please clarify. In fact, the main question is, whether you want that
amount of said iButtons (5-10 pcs) exactly at once, or rather you want
only to set up reader stations. That is, iButton reader stations can be
connected to ONE one-wire bus provided there is no collision, i. e. only
one iButton is connected at one time. With other words: one one-wire bus
can serve a vaste amount of reader stations IF there is only one button.
Further: Dallas provides a sophisticated mechanism called Search ROM which
makes possible to connect more Buttons at a time to a particular bus. And
this only one pin of a PIC!

The allowed length of the bus I do not know off the cut, but this can be
the major factor to calculate the number of PICS, which, on the other
hand, can be connected together to a RS-485 bus.

I hope this helps.

Regards,
Imre


On Thu, 21 Oct 1999, Les wrote:

> Hi.
> I was looking into the single-wire iButtons, and wanted to hook up aprox 100
> "reader-stations" spread out over 50,000 square feet, which all funnel down
> to a single PC via serial port. (Or perhaps a couple serial ports if need
> be)
>
> What I envision is having several pics, each having the capability to
> provide contacts to read 5-10 iButtons..  Each of these pics would reside on
> some common bus and eventually stream the data to a PC with a serial port.
> Each contact station would append a "station-id" to the 64bit serial number
> that the iButton reports...
>
> Has anyone been exposed to a setup like this?
>
>
> Leslie Bester
> Chief Technical Officer
> Gallmark Corporation
> 500-280 Smith St.
> Winnipeg, MB.   R3C 1K2
>
> Contact Specifications:
> 204-944-1119 (voice office)
> 204-949-0768 (fax office)
> 204-933-5164 (pager)
> 204-229-1082 (cellular)
> les@gallmark.mb.ca (email)
> pager@gallmark.mb.ca (email pager)
>
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