SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
The SSI includes a programmable bit rate clock divider and prescaler to generate the serial output clock. Bit rates are supported to 2 MHz and higher, although maximum bit rate is determined by peripheral devices.
The serial bit rate is derived by dividing-down the input clock (CMCLK). The clock is first divided by an even prescale value CPSDVSR from 2 to 254, which is programmed in the SSI Clock Prescale (SSICPSR) register. The clock is further divided by a value from 1 to 256, which is 1 + SCR, where SCR is the value programmed in the SSI Control 0 (SSICR0) register.
The frequency of the output clock SSIClk is defined by:
For master mode, the system clock must be at least two times faster than the SSIClk, with the restriction that SSIClk cannot be faster than (CMCLK/2).
For slave mode, the system clock must be at least 12 times faster than the SSIClk. In slave mode, maximum frequency of operation is (CMCLK/12).
See the Electrical Characteristics chapter in the device data sheet to view SSI timing parameters.