The Intel® Quartus® Prime software does not automatically generate the I/O timing constraints for the Generic Serial Flash Interface Intel® FPGA IP file. To enable the SPI pin interface using the general purpose I/O pins, you must manually enter the timing constraints. Follow the timing guidelines and examples to ensure that the Timing Analyzer analyzes the I/O timing correctly.

• Constrain the input clock of the Generic Serial Flash Interface Intel® FPGA IP. Example:

  #**************************************************************
  # Create Clock
  #**************************************************************
  #constrain the base clock using create_clock, this is typically a clock coming into the device on an input clock pin
  #here, clk_clk is a 10ns clock with a 50 percent duty cycle, where the first rising edge occurs at 0ns applied to port clk_clk 
  create_clock -name {clk_clk} -period 10.000 -waveform { 0.000 5.00 } [get_ports {clk_clk}]

• Create a timing constraint to dclk, which is the SPI output clock from Generic Serial Flash Interface Intel® FPGA IP. The maximum SPI clock is half of the input clock. Example:

  #**************************************************************
  # Create Generated Clock
  #**************************************************************
  #constrain the generated clock dclk. The input clock of GSFI IP is used and created a counter logic to generate a slower DCLK that is used as SPI clock  
  #here, we set the maximum dclk, which is half of the input clk_clk
  #refer to the GSFI UG, and you find that the maximum SPI clock baud-rate divisor is 2.
  create_generated_clock -name {dclk_int} -source [get_ports {clk_clk}] -divide_by 2  [get_pins {u0|intel_generic_serial_flash_interface_top_0|intel_generic_serial_flash_interface_top_0|qspi_inf_inst|flash_clk_reg|q}]
  create_generated_clock -name {dclk} -source [get_pins {u0|intel_generic_serial_flash_interface_top_0|intel_generic_serial_flash_interface_top_0|qspi_inf_inst|flash_clk_reg|q}] [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_dclk}]

• Set a multicycle path to change the setup and hold clock relationship between the input clock and the SPI clock. Example:
  Note: The multicycle path is different in Intel® Quartus® Prime Pro Edition and Intel® Quartus® Prime Standard Edition.
  • In Intel® Quartus® Prime Pro Edition:

    #**************************************************************
    # Set Multicycle Path
    #**************************************************************
    # For a divide by 2 DCLK
    # SPI lactched data on rising edge dclk and FPGA driven data output on rising edge clk_clk
    set_multicycle_path -setup -start -from  [get_clocks {clk_clk}]  -to  [get_clocks {dclk}] 2
    set_multicycle_path -hold -start -from  [get_clocks {clk_clk}]  -to  [get_clocks {dclk}] 1
    # SPI driven data on falling edge of dclk and FPGA latched data on failing edge of clk_clk
    set_multicycle_path -setup -end -from [get_clocks {dclk}] -to [get_clocks {clk_clk}]  2
    set_multicycle_path -hold -end -from [get_clocks {dclk}] -to [get_clocks {clk_clk}]  1
    

  • Intel® Quartus® Prime Standard Edition:

    #**************************************************************
    # Set Multicycle Path
    #**************************************************************
    # For a divide by 2 DCLK
    # SPI lactched data on rising edge dclk and FPGA driven data output on rising edge clk_clk
    set_multicycle_path -setup -start -from  [get_clocks {clk_clk}]  -to  [get_clocks {dclk}] 2
    set_multicycle_path -hold -start -from  [get_clocks {clk_clk}]  -to  [get_clocks {dclk}] 1
    # SPI driven data on falling edge of dclk and FPGA latched data on second rising edge of clk_clk
    set_multicycle_path -setup -end -from [get_clocks {dclk}] -to [get_clocks {clk_clk}]  1
    set_multicycle_path -hold -end -from [get_clocks {dclk}] -to [get_clocks {clk_clk}]  1
    

• Set the input and output delays for the quad serial peripheral interface (QSPI) IO pin. Example:

  #**************************************************************
  # Set Input Delay
  #**************************************************************
  #$input_delay is determined by Tco values and board parameters (outside of FPGA) 
  #$input_delay_max = data_trace_max - clk_trace_min + ext_tco_max
  #$input_delay_min = data_trace_min - clk_trace_max + ext_tco_min
  
  set_input_delay -clock { dclk } -max -clock_fall -add_delay $input_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[0]}]
  set_input_delay -clock { dclk } -min -clock_fall -add_delay $input_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[0]}]
  set_input_delay -clock { dclk } -max -clock_fall -add_delay $input_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[1]}]
  set_input_delay -clock { dclk } -min -clock_fall -add_delay $input_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[1]}]
  set_input_delay -clock { dclk } -max -clock_fall -add_delay $input_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[2]}]
  set_input_delay -clock { dclk } -min -clock_fall -add_delay $input_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[2]}]
  set_input_delay -clock { dclk } -max -clock_fall -add_delay $input_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[3]}]
  set_input_delay -clock { dclk } -min -clock_fall -add_delay $input_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[3]}]

  #**************************************************************
  # Set Output Delay
  #**************************************************************
  #$output_delay is determined by Th and Tsu values and board parameters (outside of FPGA) 
  #$output_delay_max = data_trace_max + Tsu - clk_trace_min
  #$output_delay_min = data_trace_min - Th - clk_trace_max
  set_output_delay -clock { dclk } -max -add_delay $output_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[0]}]
  set_output_delay -clock { dclk } -min -add_delay $output_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[0]}]
  set_output_delay -clock { dclk } -max -add_delay $output_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[1]}]
  set_output_delay -clock { dclk } -min -add_delay $output_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[1]}]
  set_output_delay -clock { dclk } -max -add_delay $output_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[2]}]
  set_output_delay -clock { dclk } -min -add_delay $output_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[2]}]
  set_output_delay -clock { dclk } -max -add_delay $output_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[3]}]
  set_output_delay -clock { dclk } -min -add_delay $output_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_data[3]}]
  set_output_delay -clock { dclk } -max -add_delay $output_delay_max [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_ncs}]
  set_output_delay -clock { dclk } -min -add_delay $output_delay_min [get_ports {intel_generic_serial_flash_interface_top_0_qspi_pins_ncs}]