report_rskm (::quartus::sta)

The following table displays information for the report_rskm Tcl command:

Tcl Package and Version

Belongs to ::quartus::sta 1.0

Syntax report_rskm [-h | -help] [-long_help] [-append] [-file <name> ] [-panel_name <name> ] [-stdout]
Arguments -h | -help Short help
-long_help Long help with examples and possible return values
-append If output is sent to a file, this option appends the result to that file. Otherwise, the file will be overwritten. This option is not supported for HTML files.
-file <name> Sends the results to an ASCII or HTML file. Depending on the extension
-panel_name <name> Sends the results to the panel and specifies the name of the new panel
-stdout Send output to stdout, via messages. You only need to use this option if you have selected another output format, such as a file, and would also like to receive messages.
Reports RSKM for dedicated LVDS circuitry.

In designs that use dedicated LVDS circuitry, receiver input skew
margin (RSKM) is the time margin available before the LVDS receiver
megafunction fails to operate. RSKM is defined as the total time
margin that remains after subtracting the sampling window (SW) size
and the receiver channel-to-channel skew (RCCS) from the time unit
interval (TUI), as expressed in the following formula:

RSKM = (TUI - SW - RCCS) /2

The time unit interval is the LVDS clock period (1/fmax). The sampling
window is the period of time that the input data must be stable to
ensure that the data is successfully sampled by the LVDS receiver
megafunction. The sampling window size varies by device speed
grade. RCCS is the difference between the fastest and slowest data
output transitions, including the tco variation and clock skew. To
obtain an accurate analysis of an LVDS circuit, you should assign an
appropriate input delay to the LVDS receiver megafunction. RCCS is
equal to the difference between maximum input delay and minimum input
delay. If no input delay is set, RCCS defaults to zero.
Example Usage
project_open top

# Ensure a tccs of 1ns
set_input_delay -max -clock lvds_clk 2ns [get_ports lvds_input]
set_input_delay -min -clock lvds_clk 1ns [get_ports lvds_input]

# Show lvds information
Return Value Code Name Code String Return
TCL_OK 0 INFO: Operation successful
TCL_ERROR 1 ERROR: Timing netlist does not exist. Use create_timing_netlist to create a timing netlist.
TCL_ERROR 1 ERROR: Report database is not open