7161 - Radiant: How are multiple lines of constraints handled in the device constraint editor?

Description:

When handling multiple constraint commands in a constraint files, there might be confusion in which settings are applied. This FAQ will give examples on how device constraint editor handles it. See examples below for ldc_set_sysconfig below: 

 

 1. Usecase: Only one line for ldc_set_sysconfig constraint.

In this case, there is no issue as you only have one line  for constraint command ldc_set_sysconfig , the device constraint editor should handle it properly. See below:

2.Usecase: Multiple ldc_set_sysconfig constraint for different PARAMETERS. See below for example.

 

In here multiple ldc_set_sysconfig lines are used but HAVE DIFFERENT PARAMETERS. In this case, there will be no confusion as every line sets a different setting. The only setting affected will be the setting inside { }. See below for the reflected setting in the device constraint editor.

3. Usecase: Different lines with SAME PARAMETERS

See below for example:

Notice from the sample settings above that SLAVE_SPI_PORT has a setting DISABLE on line 1 and SERIAL on line 3. In this case, there might be confusion on user side on which settings will be applied. In scenarios like these, IT IS THE LATER line that is followed. In this example, the device constraint editor will have a SLAVE_SPI_PORT setting of SERIAL and the DISABLE setting from line 1 will not take effect.

IMPLICATIONS:

During multiple lines of same commands in the constraint files. User should make sure that there are no conflicting settings such as the same in usecase 3. Take note that no warning or error will occur if the command has valid format of arguments.

 

SOLUTION/GENERAL RECOMMENDATIONS:

• Always check the device constraint editor if it reflects the settings intended. To make sure that there are no conflicting parameter settings use Device Constraint editor when setting constraints.

• If editing the .pdc file manually, make sure to always check if the desired setting is reflected in the device constraint editor.

 

 

 

• Related Articles

• 7262 - Radiant and Diamond: HDL pin constraints not seen in Spreadsheet View/Device Constraint Editor

  Description: In Lattice Radiant and Diamond, while using the Spreadsheet View/Device Constraint Editor, it is possible to not see the HDL pin constraints reflected in GUI. Solution: This may be because the pins mentioned in the lines of code have ...

• 6485 - Lattice Radiant: What is Glitchfilter in Device constraint editor?

  Glitch Fliter is used to prevent short-duration events of glitches, This is used to prevent False tripping on noise in a system. GLITCHFilter in device constraints , enables 1ns glitch filtering.

• 6329 - Lattice Radiant: Why do Radiant constraint editors remove customer variables and equations in PDC (constraints) file?

  TCL commands and Constraint Commands cannot be joint on to the same constraint file. The Timing and Physical constraints found in constraint file (.pdc) are the only object accepted and read by the tool. The TCL commands for setting certain variables ...

• 6440 - Device Constraint Editor: How to choose the D-PHY location for Crosslink-NX?

  Description: To set the location of the desired HARD DPHY module via Radiant, do the following procedures: (1) Create a top module either using verilog or vhdl source code. (2) Under the top module, insert the synthesis loc = DPHY1 inside the ...

• 7277 - Lattice Radiant / PLL: What compilation process or stage does the software automatically define the create_generated_clock constraints of the PLL clock outputs? Can the user use the generated clocks on other constraints define in the pre-synthesis stage (e.g. set_clock_groups, etc.)?

  Any clock output of the PLL has an automatically create_generated_clock constraint defined in the post-synthesis stage. Thus, user can use the generated clocks on their constraints as long as they are using post-synthesis constraints. If the user ...