I have used the SPI on the 18C452 to talk with 15 slaves.
I've had great success for years now noving streams of data to/from slaves.

Now I want to use the Slave Select feature.

The selected slave gets the first byte and generates the appropriate IRQ.
The slave moves the received byte into the appropriate memory location,
clears the IRQ flag bit, returns from the IRQ....

The next byte from the master is TOTALLY ignored, no IRQ generated.

Can this mean that the master must de-select the slave between bytes?
The master currently is asserting Slave Select for the entire stream of bytes...

The system works just fine if I don't use the built in Slave Select feature.

I am ready to eat crow if you show me where my error in thinking is...




BTW:  The spec. sheet 18C452 page 122 has what I think is an error...
14.2.1.2 ENABLING SPI I/O

.
.
.
SDO must have TRISC<5> bit cleared.  (Sure! Makes sense)

SCK (Slave mode) must have TRISC<3> bit set. (Also makes sense)
SS must have TRISC<4> bit set.  (HUH?  SS is TRISA<5>!!!)

I could believe:
SDI must have TRISC<4> bit set. (You have to set the pin to input to recieve data !)
SS must have TRISA<5> bit set. (You have to set the pin to input to recieve slave select!)

And YES, I'm at work today tring to get the system going again.

Any Help is gratefully appreciated.

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  |  __O    Thomas C. Sefranek  tcs@cmcorp.com
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