LM3S5K36 Datasheet, PDF (669/1050 Pages) Texas Instruments – Stellaris® LM3S5K36 Microcontroller

Stellaris^® LM3S5K36 Microcontroller
14.3.4.6
Freescale SPI Frame Format with SPO=1 and SPH=1
The transfer signal sequence for Freescale SPI format with SPO=1 and SPH=1 is shown in Figure
14-9 on page 669, which covers both single and continuous transfers.
Figure 14-9. Freescale SPI Frame Format with SPO=1 and SPH=1
SSIClk
SSIFss
SSIRx
SSITx
Q MSB
MSB
4 to 16 bits
LSB Q
LSB
Note: Q is undefined.
In this configuration, during idle periods:
■ SSIClk is forced High
■ SSIFss is forced High
■ The transmit data line SSITx is arbitrarily forced Low
■ When the SSI is configured as a master, it enables the SSIClk pad
■ When the SSI is configured as a slave, it disables the SSIClk pad
If the SSI is enabled and valid data is in the transmit FIFO, the start of transmission is signified by
the SSIFss master signal being driven Low. The master SSITx output pad is enabled. After an
additional one-half SSIClk period, both master and slave data are enabled onto their respective
transmission lines. At the same time, SSIClk is enabled with a falling edge transition. Data is then
captured on the rising edges and propagated on the falling edges of the SSIClk signal.
After all bits have been transferred, in the case of a single word transmission, the SSIFss line is
returned to its idle high state one SSIClk period after the last bit has been captured.
For continuous back-to-back transmissions, the SSIFss pin remains in its active Low state until the
final bit of the last word has been captured and then returns to its idle state as described above.
For continuous back-to-back transfers, the SSIFss pin is held Low between successive data words
and termination is the same as that of the single word transfer.
14.3.4.7
MICROWIRE Frame Format
Figure 14-10 on page 670 shows the MICROWIRE frame format for a single frame. Figure
14-11 on page 671 shows the same format when back-to-back frames are transmitted.
January 21, 2012
669
Texas Instruments-Production Data