The SigmaDSP products (and most devices from Analog Devices with SPI ports) use SPI Mode 3, in which CPOL = 1 and CPHA = 1.
CPHA = 1: The data changes on the falling edge of the clock and is read/written on the rising edge of the clock.
CPOL = 1: When the bus is idle, the clock signal is high.
For reference:
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(image from Total Phase, http://www.totalphase.com/ )
This FAQ was generated from the following discussion: Looking for detailed info on adau1961 spi protocol