In this article, we explore several crucial aspects related to power domain concepts in UPF. We begin by explaining the fundamental power domain concept, providing a clear understanding of its importance in power management. The discussion then moves to the implementation of a power domain with a single hierarchical instance, elaborating on how it functions within a design. We also cover the creation of power domain instances with child elements, highlighting the complexities and benefits of such configurations. Additionally, we delve into the process of creating further hierarchy within power domains, illustrating how designers can manage and optimize power distribution effectively. This article includes a detailed explanation of the UPF power domain creation command, accompanied by a practical example to demonstrate its application. Lastly, we address the commands for creating UPF power ports and power nets, emphasizing their roles in establishing robust power connections within the design framework.
Power Domain (PD) Concept :
Blocks which can be operated with the same power supply are identified & tied together. This forms a Power Domain. A particular power domain can be completely kept OFF or ON irrespective of the neighboring block. A power domain contains a collection of design elements that share a primary power and ground supply net. The logic hierarchy level where a power domain is created is called the scope of the power domain. Any design elements that belong to a power domain are said to be in the extent of that power domain.
PD with Single-Hierarchy-Instance:
In this case the only element in the power domain is A, which could be a Hard Macro or a Soft IP (e.g., an instance of a Verilog module).
Instance with Child Elements :
Here the scope of the power domain is the same as the extent, and the power domain is contiguous.
- Supply port on A is created using create_supply_port command .
- Then supply port is connected to supply net using connect_supply_net command.
- create_supply_net command applied explicitly in scope A and implicitly in U1 and U2 .
- Supply ports implicitly created on U1 and U2 to connect all the supply nets together.
PD-A contains U1/UA and U2:
Here the topology of the logic design is even more complex. Here the power domain consists of U1/UA and U2. The two instances in the same power domain which are neither contiguous nor adjacent in the logic design, resulting in a non-contiguous power domain.
In this case, when the create_supply_net command is executed to create a supply net in the power domain, the supply net is explicitly created in A using the name specified in the create_supply_net command.
Supply ports and supply nets are also implicitly created in U1, U1/UA, and U2. The supply net in U1 connects only to the port on U1 and U1/UA.
Power Domain Creation Command:
A power domain is created using UPF command :
create_power_domain <domain_name> [-elements list] [-include_scope] [-scope instance_name]
<domain_name> The new power domain; this shall be a simple (non-hierarchical) name.
[-elements list] Use this set of design elements in the power domain.
[-include_scope] Include the scope of the domain in the extent of the power domain.
[-scope instance_name] Create the power domain within this logic hierarchy scope.
Power Domain : Example
Power Domain : Example
Power Ports & Power Nets:
- Power comes from main power sources through I/O pad-ring via Power Port.
- The Supply Nets are used to connect Power Ports to Power Pins of each of the cells.
- create_supply_port <port_name> [ -domain domain_name ] [ -direction < in | out >]
- create_supply_net <net_name> -domain <domain_name> [-reuse] [-resolve <unresolved | one_hot | parallel>]
-reuse Extend net_name as a supply net within domain_name. No new nets are created.
-resolve <unresolved | one_hot | parallel> A resolution mechanism which determines the state and voltage of the supply net from the state and voltage values supplied by each of the individual switches. The default is unresolved.
Watch the video lecture here :
Courtesy : Image by www.pngegg.com
