In the case of a single word transfer, after all bits have been transferred, the
SSInFss
line is returned
to its idle High state one
SSInClk
period after the last bit has been captured.
For continuous back-to-back transfers, the
SSInFss
pin is held Low between successive data
words, and termination is the same as that of the single word transfer.
17.3.7.5
Freescale SPI Frame Format with SPO=1 and SPH=0
Single and continuous transmission signal sequences for Freescale SPI format with
SPO
=1 and
SPH
=0 are shown in Figure 17-7 on page 1238 and Figure 17-8 on page 1238.
Note:
This Freescale SPI frame format configuration is only available when operating in Legacy
SSI mode of operation.
Figure 17-7. Freescale SPI Frame Format (Single Transfer) with SPO=1 and SPH=0
SSInClk
SSInFss
SSInRx
SSInTx
Q
MSB
MSB
LSB
LSB
4 to 16 bits
Note:
Q is undefined.
Figure 17-8. Freescale SPI Frame Format (Continuous Transfer) with SPO=1 and SPH=0
SSInClk
SSInFss
SSInTx/SSInRx
MSB
LSB
LSB
MSB
4 to 16 bits
In this configuration, during idle periods:
■
SSInClk
is forced High
■
SSInFss
is forced High
■ The transmit data line
SSInDAT0/SSInTX
is tristated
■ When the QSSI is configured as a master, it enables the
SSInClk
pad
■ When the QSSI is configured as a slave, it disables the
SSInClk
pad
June 18, 2014
1238
Texas Instruments-Production Data
Quad Synchronous Serial Interface (QSSI)