Ints are not needed. Here's my macro code to send/rcv SPI:

; send one byte out/in on SPI
; operates from Bank0
; value is w is sent out, contains output in w when returns
sndSPI  macro
             movwf   sspbuf
             bsf     status,5
             btfss   sspstat,bf
             goto    $-1
             bcf     status,5
             movf    sspbuf,w
       endm
;

--Bob

----- Original Message -----
From: "Thomas N" <thomasn101@HOTMAIL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, November 27, 2002 11:12 PM
Subject: Re: [PIC]: SPI protocol


> Thank you for your comments!
>
> When you write data to SSPBUF, how do you know when the data transmision
> is completed?  The only way to know this is thru interrupt.  If I send 2
> bytes of data, interrupt will happen 2 times.  How do I know which
> interrupt is the second interrupt(when the second byte is sent)?
>
> Regards,
> Thomas
>
>
> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Bob Axtell
> Sent: Wednesday, November 27, 2002 8:45 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]: SPI protocol
>
> > I have some problems with the project I am working on, and I need your
> > help!
> >
> > 1.      I have 2 devices on the SPI bus (one 16-bit and one 8-bit).
> > Each device has its own Chip Select signal.  What I want to do is:
> >
> > For 16-bit device
> >             Select the chip
> >             Send 16 bits of data
> >             Deselect the chip
> >
> > For 8-bit device
> >             Select the chip
> >             Send 8 bits of data
> >             Deselect the chip
> >
> > I have no problem writing the code for multiple 8-bit devices, but
> when
> > it comes to a mixture of 8-bit and 16-bit devices, I am totally stuck.
> > I am thinking of using a variable in the ISR to indicate whether it is
> a
> > 8-bit or 16-bit device, but I think it needs Mutual Exclusion.  I am
> > using the 16F877.  Please help!
>
> Unless the chip is selected, whatever happens on the clock and data
> lines means nothing. [16b]: Just select that chip, send the first
> byte/capture
> data out, then send the second byte/capture data out, then deselect the
> chip.
>  [8b]: Just select the chip, send the byte/capture data out, then
> deselect
> the
> chip.
>
> > 2.      The SPI module on the 16F877 can be configured to run at
> > different speed.  Don't we always want to run it at the fastest speed?
>
> Not quite true. Some SPI devices cannot have a clock faster than 1Mhz
> or even 400Khz. At 20Mhz, the fastest SPI is 4Mhz.
>
> > Thank you for your help!
> > Best regards,
> > Thomas
> >
> > --
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> >
> >
> >
>
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>

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