Arria V Hard Processor System Technical Reference Manual

ID 683011
Date 12/02/2022
Public
Document Table of Contents

16.4.12. Clocks

There are two clock inputs to the quad SPI controller: l4_mp_clk and qspi_ref_clk; and one clock output: qspi_clk. The quad SPI flash controller uses the l4_mp_clk clock to clock the data slave transfers and register slave accesses. The qspi_ref_clk clock is the reference clock for the quad SPI controller and is used to serialize the data and drive the external SPI interface. The qspi_clk clock is the clock source for the connected flash devices.

The following is true for the following reference clocks:
  • qspi_ref_clk should be greater than l4_mp_clk
  • qspi_ref_clk must be greater than two times qspi_clk

The qspi_clk clock is derived by dividing down the qspi_ref_clk clock by the baud rate divisor field (bauddiv) of the cfg register.