At 01:16 PM 1/1/97 -0700, you wrote:
>Hello all,
>
>Has anyone looked into using the iButton cans (www.ibutton.com) from Dallas
>Semi? They use a 1-wire interface which probably would work with a PIC,
>though there may be some issues dealing with the 115kbit/sec transfer rate.
>These things seem like a great application of the PIC, which could provide
>a gateway to real-world elements using the DS1990 as an authentication
>tool. Am I totally wrong here? Sorry, I've been lurking in this group for a
>while, and haven't made the leap from Stamps to PICs, so I'm not really
>familiar with the throughput possible with an entry-level PIC.
>
>Thanks,
> Nathan

 Nathan,
 As plenty of other people on the list have stated, hooking a DS1990 to a
pic really is not all that hard to do. I did a digital 'lock' using a 16c54
that worked just fine. I would however like to see some of the dallas/pic
crc routines because I just faked it.

 As for the 115kbit/sec specification, that's a bit misleading. The basic
time slot period can be anything from 60us to 120us. I believe the 115kbit
transfer rate comes from the Dalles Semiconductor software/hardware trick of
using the IBM serial port to generate the 1-wire protocol.

hope this helps....

carl