> -----Original Message-----
> From: D Lloyd [SMTP:dan.lloyd@GB.ABB.COM]
> Sent: Wednesday, September 20, 2000 3:27 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [OT]: PC simulating SPI slave/master
>
>
>
> Hi,
>
> Thinking a bit more about it, the PC will be purely the slave device and I
> dont
> really need any "master" functionality. I have found a program that
> squirts out
> SPI data from a PC so this may suffice to some extent, although I wanted
> to
> create my own data structures etc.
>
That sounds very much like it's the master to me.  Is the PC responsible for
generating the clock (SCK) or does the embedded system produce the clock?

> As to the speed, the embedded host can only
> clock fast enough for 60 kilobits per second; I imagine that if this
> 533Mhz PC
> cannot manage that (under DOS - I just know Windows is going to be
> trouncing it)
> then it is time to pack in!
>
As a master you could probably get in excess of 1Mbit/sec through the serial
port in DOS with a fast CPU and tight coding.  You could even use something
like VB and get a decent data rate, although timing is tricky.  With a slave
implementaion, the PC has to poll the clock to look for a 1-0 or 0-1
transistion before reading in the state of the data line.  You would have to
sample the clock at several times the maximum speed of the bus to get
reliable results.

> The other way I can imagine it working is for me to borrow our contractors
> 877
> dev kit and plonk a load of data in that, then set it up to deliver the
> synchronous serial data.......Oh joy(!)
>
> Regards,
> Dan
>
I was going to suggest knocking up an SPI to RS232 converter using a PIC!
Nice little project for you.  But serialously :o) I would use Qbasic or a
Dos compiler to do the job of a master.

Mike




> |------------->
> |(Embedded    |
> |image moved  |
> |to file:     |
> |pic16904.pcx)|
> |             |
> |------------->
>
> >------------------------------------------------------------------------|
>   |Michael Rigby-Jones <mrjones@NORTELNETWORKS.COM>
> |
>   |20/09/2000 15:11
> |
>
> >------------------------------------------------------------------------|
>
>
>
> Please respond to pic microcontroller discussion list
> <PICLIST@MITVMA.MIT.EDU>
>
> To:   PICLIST@MITVMA.MIT.EDU
> cc:    (bcc: Dan Lloyd/GBPTD/ABB)
> Subject:  Re: [OT]: PC simulating SPI slave/master
>
> Security Level:?         Internal
>
>
>
> I don't have any SPI code, but a master implementation would be very
> simple
> to write, even in something like QBASIC.  I think making an SPI slave that
> works at reasonable frequencies will be pretty hard work though.  You will
> have to be polling the clock line at a ridiculous rate for say, a 500KHz
> SPI
> clock.  Unlike I2C (AFAIK) you can't use clock stretching to slow the
> slave
> down.
>
> Mike
>
>
>
> > -----Original Message-----
> > From: D Lloyd [SMTP:dan.lloyd@GB.ABB.COM]
> > Sent: Wednesday, September 20, 2000 2:18 PM
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      [OT]: PC simulating SPI slave/master
> >
> > Hi,
> >
> > I am on the verge of writing some parallel port control code to simulate
> > the PC
> > as being an SPI slave or master to prove out an embedded system.
> > Eventually, I'd
> > like the PC to supply data (as though it were the peripheral it is
> > simulating)
> > to the embedded micro for testing purposes (as the peripheral doesnt
> > actually
> > exist, as yet....if that makes sense!)
> >
> > I just wondered if anyone has written such a beast? I dont imagine too
> > much work
> > involved (just bit bashing the parallel port to generate the clock and
> > data) but
> > it could save some valuable time if anyone out there has done this
> > already..
> >
> > Any help would be greatly appreciated.
> >
> > Regards,
> >
> > Dan Lloyd
> >
> > --
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