BUILD_ECS MACRO

The BUILD_ECS MACRO Creates a Named ELECTRICAL_CONSTRAINT_SET (ECS) which can be applied to matching NetNames 

Electrical Constraint Sets

An Electrical Constraint Set (ECS) is use to constrain the Electrical attributes of Nets 

BUILD_ECS can constrain many different parameters for a group of signals, and can also apply a PHYSICAL_CONSTRANT_SET (PCS) to the same group.

PARAMETERS that can be constrained include VIAS_MAX,VIAS_MATCH,MIN_PROP_DLY,MAX_PROP_DLY,MIN_TOTAL_ETCH,MAX_TOTAL_ETCH,

TOP_MAP_MODE,TOP_VERIFY_SCHEDULE,TOP_SCHEDULE_CONTROL,STUB_LENGTH,MAX_EXPOSED,MAX_PARALLEL,LAYER_SETS

BUILD_ECS  

This Line tells dal constraints to create a new named ECS

syntax: 

BUILD_ECS  | NAME=> | NAME_FOR_ECS

the TYPE=> Attribute  tells dal constraints what type of ECS the user wants to create

Valid options are: DIFF_PAIR and SINGLE_ENDED

Syntax:

TYPE=>[DIFF_PAIR|SINGLE_ENDED]

The DIFF_PAIR ECS is used to create Dynamic (DPA) and Static Differential Pair Routing Rules.

These are very powerful constraints which Allegro PCB uses to control the skew between the diff_pair mate nets. 

The DYNAMIC 

ASSIGN_PCS

The ASSIGN_PCS=>Attribute assigns an existing  PCS to any nets assigned to this ECS

The PCS may have been created using the BUILD_PCS MACRO or when dal constraints imported the stackup.

Syntax: 

ASSIGN_PCS=>PCS_NAME

Example

ASSIGN_PCS=>90_OHM_DIFF

TRACE_WIDTH_PARAMETERS

the TRACE_WIDTH_PARAMETERS attribute provides a list of routing widths and spacing for each routing layer (using the UNITS attribute)

example syntax for TYPE=>DIFF_IMPEDANCE  

TRACE_WIDTH_PARAMETERS=> L1,L24=10/7.5:L4,L5,L8,L9,L16,L17,L20,L21=3.7/5

This specifies that target diff_pair nets  on Layers 1 and 24  should be routed at 10 mils and 7.5 mil edge to edge spacing. On layers 4,5,6,7,8,9,16,17 and 21 target diff_pairs should be routed at 3.75 mils and 5  mil spacing

example syntax for TYPE=>SINGLE_ENDED_IMPEDANCE 

TRACE_WIDTH_PARAMETERS=> L1,L24=12:L4,L5,L8,L9,L16,L17,L20,L21=6

This specifies that target single_ended nets  on Layers 1 and 24  should be routed at 12 mils, On layers 4,5,6,7,8,9,16,17 and 21 target single_ended nets should be routed at 6 mils

example syntax for TYPE=>POWER

MEMBERS

The MEMBERS=> Attribute tells dal constraints what nets to apply the new PCS to. 

This is an optional attribute when you are creating a PCS that will be assigned from an ECS.

The syntax is MEMBERS=>net_match1,net_match2.... net_matchN

like

MEMBERS=>P48V,P48V_RTN

This tells dal constraints to assign this PCS to any net containing 'P48V' or 'P48V_RTN'

in this case the net_match is a simple text pattern 

The MEMBERS net_matches are treated as regular expressions by dal constraints and are quite powerful.

To see more information on regular expression entry see  Regular Expressions In CadEnhance Tools

NOT_MATCHING

the NOT_MATCHING=>Attribute is optional and works together with the MEMBERS attribute to fully define the set of target nets

the NOT_MATCHING is a  comma seperated list of patterns that will be used to exclude nets from the set of nets that match the MEMBER patterns

Together the 2 attributes make very simple to define a large set of nets without having to create a very large list of specific matches