On Thu, Sep 16, 1999 at 06:06:07PM +1000, Gennette Bruce wrote:
> > -----Original Message-----
> > From: Duilio Foschi [SMTP:foschid@SUMMER.ETRURIA.NET]
> > Sent: Thursday, 16 September 1999 17:15
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      transferring data
> >
> > can PICs talk transfer data from one to another using one of their pins ?
> > (w/o a UART, I mean).
> >
> > Can 8051 uPs do the same ?
> >
> > Thank you
> >
> > Duilio Foschi
> >
>         1 pin on each for one way transfer with self syncing, 2 pins on each
> for two way transfer with self syncing, 3 pins on each if a clocking or
> comms enable signal is used to synchronize all comms.
>
>         Self syncing usually involves sending a pattern in front of the data
> to allow the receiver to do its housekeeping (break out of whatever other
> routine it was doing) and watch for the start-of-data pattern. 6 x ASCII <U>
> '01010101' is a good door bell pattern to use, followed by a null '00000000'
> and char 255 '11111111' giving a big 'ding-dong' wake up followed by an
> unmistakable 8 x 0 and 8 x 1 to identify the start of data -
>         0101010101010101010101010101010101010101010101010000000011111111
>
I'd suggest the emulation of I2C protocol, which allows 2 way transfer with
clock syncing on just two wires.
However it requires rather sophisticated software, if you are using PIC
without MSSP :-(.
--
                              Wojciech M. Zabolotny
        http://www.ise.pw.edu.pl/~wzab  <--> wzab@ise.pw.edu.pl

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