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32059L–AVR32–01/2012
AT32UC3B
BITS: Bits Per Transfer
The BITS field determines the number of data bits transferred. Reserved values should not be used.
CSAAT: Chip Select Active After Transfer
0: The Peripheral Chip Select Line rises as soon as the last transfer is achieved.
1: The Peripheral Chip Select does not rise after the last transfer is achieved. It remains active until a new transfer is requested
on a different chip select.
CSNAAT: Chip Select Not Active After Transfer
0 = The Peripheral Chip Select Line rises as soon as the last transfer is acheived
1 = The Peripheral Chip Select Line rises after every transfer
CSNAAT can be used to force the Peripheral Chip Select Line to go inactive after every transfer. This allows successful
interfacing to SPI slave devices that require this behavior.
NCPHA: Clock Phase
0: Data is changed on the leading edge of SPCK and captured on the following edge of SPCK.
1: Data is captured on the leading edge of SPCK and changed on the following edge of SPCK.
NCPHA determines which edge of SPCK causes data to change and which edge causes data to be captured. NCPHA is used
with CPOL to produce the required clock/data relationship between master and slave devices.
CPOL: Clock Polarity
0: The inactive state value of SPCK is logic level zero.
1: The inactive state value of SPCK is logic level one.
CPOL is used to determine the inactive state value of the serial clock (SPCK). It is used with NCPHA to produce the required
clock/data relationship between master and slave devices.
BITS
Bits Per Transfer
0000
8
0001
9
0010
10
0011
11
0100
12
0101
13
0110
14
0111
15
1000
16
1001
Reserved
1010
Reserved
1011
Reserved
1100
Reserved
1101
Reserved
1110
Reserved
1111
Reserved