Microchip did the WORST job implementing SPI in the PICs.
Slave select is NOT,... it is slave sync, and TX enable.

There are modes within the 4 possible that do not work with
continuous data.  There are modes that do not interrupt after
the first byte unless you disable the SPI and re enable it every byte.

There are modes that with slave select DISABLED! the SPI continued on
answering the clock/data stream.
I ended up having to add an external PAL to qualify the SPI clock
to get SPI to work correctly.

  *
  |  __O    Thomas C. Sefranek   WA1RHP@ARRL.NET
  |_-\<,_   Amateur Radio Operator: WA1RHP
  (*)/ (*)  Bicycle mobile on 145.41, PL 74.4

http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Thomas
> Sent: Friday, March 26, 2004 10:34 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [PIC:] SPI Slave - Need to toggle /SS signal for every byte?
>
>
> Hi,
> If a Master PIC wants to send multiple bytes of data
> to a Slave PIC (with SS enabled) using SPI, does it
> have to pull the SS line high at the end of every
> byte?  The slave receives data perfectly with this:
> - SS low
>   - Send data
>   - Delay 10ms
> - SS high
> - SS low
>   - Send data
>   - Delay 10ms
> - SS high
>
> However, The slave doesn't receive data properly with
> this:
> - SS low
>   - Send data
>   - Delay 10ms
>   - Send data
>   - Delay 10ms
> - SS high
>
> Both the slave and the master are F877 @ 20Mhz.  Did I
> do something wrong?
> Regards,
> Thomas
>
> --
> http://www.piclist.com hint: To leave the PICList
> mailto:piclist-unsubscribe-request@mitvma.mit.edu
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads