Controlling Design Implementation
CPLD Schematic Design Guide
Start with the letter ``a"
Contain two characters; the first character is ``b"
Start with ``c" and end with ``d"
Basic TIMESPEC Syntax
Within the TIMESPEC primitive, you use the following syntax to
specify timing requirements between specific end points:
The From-To statements are TS attributes that reside in the
TIMESPEC primitive. The parameters
be one of the following:
previously created TNM identifiers
groups defined in TIMEGRP symbols
Predefined groups consist of FFS or PADS and are discussed in the
"Using Predefined Groups" section. TNMs are introduced in the
"Creating User-Defined Groups Using TNMs" section. TIMEGRP
symbols are introduced in the "Creating New Groups from Existing
Keywords, such as FROM, TO, and TS appear in the documen-
tation in upper case; however, you can enter them in the TIMESPEC
primitive in either upper or lower case. You cannot enter them in a
combination of lower and upper case.
The delay parameter defines the maximum delay for the attribute.
Nanoseconds are the default units for specifying delay time in TS
attributes. You can also specify delay using other units, such as pico-
seconds or megahertz. Refer to the "Specifying Time Delay in TS
Attributes" section later in this chapter for more information on time
The following examples illustrate the use of From-To TS attributes:
The parameters source_group and dest_group must be one of the following: · predefined groups · previously created TNM identifiers · groups defined in TIMEGRP symbols Predefined groups consist of FFS or PADS and are discussed in the "Using Predefined Groups" section.