SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
The OSPI module has two main clock sources for the Octal-SPI controller.
The source for the interface clocks corresponds to the configuration and data buses. The data bus clock (OSPI_HCLK) is the main system clock used to transfer data over the data bus between a master on the system interconnect and the OSPI module. The data bus clock also drives the internal OSPI SRAM. The configuration bus clock (OSPI_PCLK) is used to access the OSPI configuration register and perform basic configuration and for interrupt handling. The OSPI reference clock (OSPI_RCLK) drives the SPI transmit and receive logic in the OSPI module. It is also used to generate the output SPI protocol clock (OSPI_OCLK) and for oversampling of the input data. Using the reference clock (OSPI_RCLK) allows the OSPI module to decouple the frequency of the SPI flash device from the device system clocks, thereby providing more flexible clocking solution.
There is no particular clock ratio requirement between configuration (OSPI_PCLK) and data bus (OSPI_HCLK) clocks.