Using TPTHRU or TPSYNC in a FROM-TO Constraint

It is sometimes convenient to define intermediate points on a path to which a specification applies. This defines the maximum allowable delay and has the following syntax.

Schematic syntax in TIMESPEC primitive

TSidentifier=FROM source_group THRU thru_point [THRU thru_point] TO dest_group allowable_delay [units]

TSidentifier=FROM source_group THRU thru_point [THRU thru_point] allowable_delay [units]

TSidentifier=THRU thru_point [THRU thru_point] TO dest_group allowable_delay [units]

UCF syntax

TIMESPEC TSidentifier=FROM source_group THRU thru_point [THRU thru_point] TO dest_group allowable_delay [units];

TIMESPEC TSidentifier=FROM source_group THRU thru_point [THRU thru_point] allowable_delay [units];

TIMESPEC TSidentifier=THRU thru_point [THRU thru_point] allowable_delay [units];

Unspecified FROM or TO, as in the second and third syntax statements, implies all points.

• identifier is an ASCII string made up of the characters A..Z, a..z, 0..9, underbar (_), and forward slash (/).
  
  
• source_group and dest_group are user-defined, predefined groups or TPSYNCs.
  
  
• thru_point is an intermediate point used to qualify the path, defined using a TPTHRU attribute.
  
  
• allowable_delay is the timing requirement.
  
  
• units is an optional field to indicate the units for the allowable delay. Default units are nanoseconds, but the timing number can be followed by ps, ns, us, ms, GHz, MHz, or KHz to indicate the intended units.
  
  

The example shows how to use the TPTHRU attribute with the THRU attribute on a schematic. The UCF syntax is as follows.

INST FLOPA TNM=A;
INST FLOPB TNM=B;
NET MYNET TPTHRU=ABC
TIMESPEC TSpath1=FROM A THRU ABC TO B 30;

The following schematic shows the placement of the TPTHRU attribute and the resultant path that is defined.

Figure 4.18 TPTHRU Example