The block design synthesis flow allows you to create complex systems using custom and AMD IP. The Vivado IP integrator creates a block design (BD) file in this flow. AMD or custom IP is added to the .bd file and connected as a system. This flow offers the following advantages:
- Encapsulates a great deal of functionality into a small design.
- Allows focus on the system rather than individual parts of the system.
- Enables easier and faster setup and synthesis of the design.
The following figure shows an example of a block design.
When creating the block design, you can run synthesis using either out-of-context (OOC) synthesis mode or global synthesis mode. If you use out-of-context synthesis mode, the block design is synthesized separately from the rest of the design. When hierarchies outside the BD file change, this enables faster resynthesis.
When you use global synthesis mode, the system compiles and synthesizes the full design each time. Setting up global synthesis mode is easier because you set constraints at a global level. However, using this mode results in a higher runtime on resynthesis. You can improve runtime using incremental synthesis.