Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 11/11/2022
Public

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19.4.6.2. Texas Instruments Synchronous Serial Protocol (SSP)

Data transfers begin by asserting the frame indicator line (ss_0_n) for one serial clock period. Data to be transmitted are driven onto the txd line one serial clock cycle later; similarly data from the slave are driven onto the rxd line. Data are propagated on the rising edge of the serial clock (sclk_out/sclk_in) and captured on the falling edge. The length of the data frame ranges from 4 to 16 or 32 bits depending on the maximum transfer size.

Note: The slave select signal (ss_0_n) takes effect only when used as slave SPI. For master SPI, the data transmission begins as soon as the output enable signal is deasserted.
Figure 89. SSP Serial Format

Continuous data frames are transferred in the same way as single data frames. The frame indicator is asserted for one clock period during the same cycle as the LSB from the current transfer, indicating that another data frame follows. †

Figure 90. SSP Serial Format Continuous Transfer