Joined: 14 Aug 2004 Posts: 1384 Location: Dallas / Fort Worth, Texas (USA)
Posted: Tue Jul 26, 2011 4:54 pm Post subject:
That is as designed for the AVR. This is from the AVR chip document (pdf)... "When configured as a Master, the SPI interface has no automatic control of the SS line. This must be handled by user software before communication can start."
I use another pin for chip select and that works. The problem is if I need pin 16 (SS) for input SPI dies. Shouldn't I be able to do that? Another words not use the SS pin for SPI at all?
EDIT: Ok I read through the data sheet again and the bascom help. It is explained so now I get it. Not exactly intuitive through.
Quote:
If SS is configured as an output, the pin is a general output pin which does not affect the SPI
system. Typically, the pin will be driving the SS pin of the SPI Slave.
If SS is configured as an input, it must be held high to ensure Master SPI operation. If the SS pin
is driven low by peripheral circuitry when the SPI is configured as a Master with the SS pin
defined as an input, the SPI system interprets this as another master selecting the SPI as a
slave and starting to send data to it.
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