TM4C1233C3PM Datasheet, PDF (933/1214 Pages) Texas Instruments – Tiva Microcontroller

Tiva^™ TM4C1233C3PM Microcontroller
SSInClk period, meaning that data is captured on the falling edges and propagated on the rising
edges of the SSInClk signal.
In the case of a single word transmission, after all bits of the data word are transferred, the SSInFss
line is returned to its idle High state one SSInClk period after the last bit has been captured.
However, in the case of continuous back-to-back transmissions, the SSInFss signal must be pulsed
High between each data word transfer because the slave select pin freezes the data in its serial
peripheral register and does not allow it to be altered if the SPH bit is clear. Therefore, the master
device must raise the SSInFss pin of the slave device between each data transfer to enable the
serial peripheral data write. On completion of the continuous transfer, the SSInFss pin is returned
to its idle state one SSInClk period after the last bit has been captured.
15.3.4.6
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
15-9 on page 933, which covers both single and continuous transfers.
Figure 15-9. Freescale SPI Frame Format with SPO=1 and SPH=1
SSInClk
SSInFss
SSInRx
Q MSB
SSInTx
MSB
4 to 16 bits
LSB Q
LSB
Note: Q is undefined.
In this configuration, during idle periods:
■ SSInClk is forced High
■ SSInFss is forced High
■ The transmit data line SSInTx is tristated
■ When the SSI is configured as a master, it enables the SSInClk pad
■ When the SSI is configured as a slave, it disables the SSInClk pad
If the SSI is enabled and valid data is in the transmit FIFO, the start of transmission is signified by
the SSInFss master signal being driven Low. The master SSInTx output pad is enabled. After an
additional one-half SSInClk period, both master and slave data are enabled onto their respective
transmission lines. At the same time, SSInClk is enabled with a falling edge transition. Data is then
captured on the rising edges and propagated on the falling edges of the SSInClk signal.
After all bits have been transferred, in the case of a single word transmission, the SSInFss line is
returned to its idle high state one SSInClk period after the last bit has been captured.
June 12, 2014
933
Texas Instruments-Production Data