SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
When the input data of the IPIPEIF module does not come from the VP but from memory, it is useful to have control of the rate at which the data is fetched from memory to avoid overflow conditions or to avoid peak bandwidth requirements. The IPIPEIF_CFG1[10] CLKSEL bit is equal to 1 for fractional divider use.
The ISP clock ISP_FCLK is divided to generate the pixel clock, which goes to the ISIF and IPIPE modules when data is read from memory (IPIPEIF_CFG1[15:14] INPSRC1 = IPIPEIF_CFG1[3:2] INPSRC2 = 1 or 3). The IPIPEIF_CLKDIV register selects the divider ratio: M and N values in the IPIPEIF_CLKDIV[15:0] CLKDIV bit field.
Given an input clock of clock rate ISP_FCLK, the fractional clock divider generates an output clock with average clock rate fOUT.
Where fOUT = ISP_FCLK x M/N, and M = 1 through 256, and N = 1 through 256.
The fractional clock divider logic is synchronous and uses only the positive clock edge of the input clock.