Routing Secondary Power and Ground Pins
To use Zroute to perform secondary power and ground pin routing,

Verify that the secondary power and ground pins have the appropriate attributes in the standard cell frame views.

Set the routing constraints for secondary power and ground pin routing.

Perform secondary power and ground pin routing by using the route_group command.

The following topics describe these steps.

Verifying the Secondary Power and Ground Pin Attributes
Before you use Zroute to perform secondary power and ground pin routing, you must verify that the cell libraries have the correct attributes on the secondary power and ground pins of the standard cell frame views.

The following attributes are required for secondary power and ground pins:

is_secondary_pg

This attribute must have a setting of true.

port_type

This attribute must have a setting of power or ground.

To verify that these attributes are correctly set on the library pins in the standard cell frame view, use the following command:

icc2_shell> report_attributes -application \
   [get_lib_pins -of_objects reflib/cell/frame -all \
      -filter "name == attr_name"]
where reflib is the cell library name, cell is the name of the library cell you want to check (or * if you want to check all library cells), and attr_name is either is_secondary_pg or port_type.

See Also
Identifying Secondary PG Pins
Setting the Routing Constraints
You can set routing constraints for secondary power and ground pin routing in the same way as for regular signal routing. For example, you can set constraints by

Defining the minimum and maximum routing layers by using the set_routing_rule command

For more information about using the set_routing_rule command, see Specifying Net-Specific Layer Constraints.

Specifying the preferred pin connections by setting the route.common.single_connection_to_pins and route.common.connect_within_pins_by_layer_name application options

For example, to require a single connection to the secondary power and ground pins and require that the M1 connections use vias contained within the pin shapes, use the following command:

icc2_shell> set_app_options \
   -name route.common.single_connection_to_pins \
   -value standard_cell_pins
icc2_shell> set_app_options \
   -name route.common.connect_within_pins_by_layer_name \
   -value {{M1 via_standard_cell_pins}}
Defining the maximum number of power or ground pins in a cluster by setting the route.common.number_of_secondary_pg_pin_connections application option

A cluster is a set of connected secondary power or ground pins that has one connection to a PG strap or ring. By default, the value of this option is 0, which means that there is no limit on the number of secondary power or ground pins in a cluster.

For example, to connect all secondary power and ground pins directly to a PG strap or ring, use the following command:

icc2_shell> set_app_options \
   -name route.common.number_of_secondary_pg_pin_connections \
   -value 1
Defining a nondefault routing rule for secondary power and ground pin routing

For example, to define a nondefault routing rule named wideSVDD for wide M1 and M2 and set the nondefault routing rule on the VDD2 net, to which the secondary power and ground pins are connected, use the following commands:

icc2_shell> create_routing_rule wideSVDD -widths { M1 0.3 M2 0.3 }
icc2_shell> set_routing_rule -rule wideSVDD {VDD2}
For more information about using nondefault routing rules, see Using Nondefault Routing Rules.

By default, the constraints apply to both the secondary power and ground connections and the tie-off connections. To separate these connections so that you can set constraints only for the secondary power and ground connections, set the route.common.separate_tie_off_from_secondary_pg application option to true.

Routing the Secondary Power and Ground Pins
If the secondary power and ground pins have the appropriate attributes in the frame view, you can use Zroute to route the secondary power and ground pins.

By default, Zroute performs four topology ECO iterations to fix secondary PG cluster fanout violations.The topology ECO iterations can be time consuming, so you can control the effort level, and therefore the runtime, by setting the route.detail.topology_eco_effort_level application option to one of the following values:

off, which disables topology ECO

low, which peforms one topology ECO iteration

medium, which peforms four topology ECO iterations; this is the default

high, which peforms eight topology ECO iterations

For example, to connect the secondary power pins to the VDD1 net, run the following command:

icc2_shell> route_group -nets VDD1
The following example add new cells, which have secondary power and ground pins, to a block; logically connects the power and ground pins; and then connects the secondary power pins to the VDD2 net.

icc2_shell> add_buffer {TOP/U1001/Z} {libA/BUFHVT} \
   -new_cell_names mynewHVT 
icc2_shell> add_buffer {TOP/U1002/Z} {libA/BUFHVT} \
   -new_cell_names mynewHVT 
icc2_shell> legalize_placement
icc2_shell> connect_pg_net -automatic
icc2_shell> route_group -nets {VDD2}