SWCU185G January 2018 – June 2024 CC1312PSIP , CC1312R , CC1352P , CC1352R , CC2642R , CC2642R-Q1 , CC2652P , CC2652PSIP , CC2652R , CC2652RB , CC2652RSIP , CC2662R-Q1
Figure 14-23 shows the transfer signal sequence for Motorola SPI format with SPO = 1 and SPH = 1, which covers both single and continuous transfers.
In this configuration, the following occurs during idle periods:
If the SSI is enabled and valid data is in the TX FIFO, the start of transmission is signified by the SSIn_FSS master signal going low. The master SSIn_TX output DIO is enabled. After an additional one-half SSIn_CLK period, both master and slave data are enabled onto their respective transmission lines. At the same time, SSIn_CLK is enabled with a falling-edge transition. Data is then captured on the rising edges and propagated on the falling edges of the SSIn_CLK signal.
For a single word transmission, after all bits are transferred, the SSIn_FSS line returns to its IDLE high state one SSIn_CLK period after the last bit is captured.
For continuous back-to-back transmissions, the SSIn_FSS pin remains in its active low state until the final bit of the last word is captured and then returns to its IDLE state.
For continuous back-to-back transfers, the SSIn_FSS pin is held low between successive data words and terminates like a single-word transfer.