Wiznet W7500, Справочное руководство

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W7500x Reference Manual Version1.1.0
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Figure 58 shows the Texas Instruments synchronous serial frame format when back-to-back
frames are transmitted.
SSPFSSOUT/
SSPFSSIN
SSPTXD/
SSPRXD
4 to 16 bits
SSPCLKOUT/
SSPCLKIN
MSB LSB
nSSPOE (=0)
Figure 58.
Texas Instruments synchronous serial frame format, continuous transfers
Motorola SPI frame format
The Motorola SPI interface is a four-wire interface where the SSPFSSOUT signal behaves as a
slave select. The main feature of the Motorola SPI format is that you can program the inactive
state and phase of the SSPCLKOUT signal using the SPO and SPH bits of the SSPSCR0 control
register.
SPO, clock polarity
When the SPO clock polarity control bit is LOW, it produces a steady state LOW value on the
SSPCLKOUT pin. If the SPO clock polarity control bit is HIGH, a steady state HIGH value is
placed on the SSPCLKOUT pin when data is not being transferred.
SPH, clock phase
The SPH control bit selects the clock edge that captures data and enables it to change state.
It has the most impact on the first bit transmitted by either permitting or not permitting a
clock transition before the first data capture edge.
When the SPH phase control bit is LOW, data is captured on the first clock edge transition.
When the SPH clock phase control bit is HIGH, data is captured on the second clock edge
transition.
Figure 59 and Figure 60 show single and continuous transmission signal sequences for Motorola
SPI format with SPO=0, SPH=0.