Connecting Interface Signals - 2020.2 English

Vivado Design Suite User Guide: Designing IP Subsystems Using IP Integrator (UG994)

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2020.2 English

To connect to the individual signals or buses that are part of an interface pin, you can expand the interface pin to display those individual signals. Clicking the + symbol on the interface expands the interface to display its contents.

In the following figure, you can see that the interface pin M_AXI_DP on the microblaze_0 instance is connected to the S00_AXI interface pin on the microblaze_0_axi_periph instance. In addition, two individual signals of the interface (AWVALID and BREADY) are connected to a third instance, util_vector_logic_0, to AND the signals.

When individual signals of an interface are separately connected from the rest of the interface, the signals must include all of the pins needed to complete the connection. In the example shown in the following figure, both the master and slave AXI interface pins are expanded to enable connection to the individual AWVALID and BREADY signals, as well as connecting to the pins of the Utility Vector Logic cell.

Important: Individually connected interface signals are no longer connected as part of the interface in the BD. The individual signal is essentially removed from the interface. The entire signal must be manually connected.
Figure 1. Expanding the Interface to Make a Connection

When connections to an interface pin are overridden by connection to individual signals or bus pins of the interface, the Vivado tool issues a warning similar to the following:

WARNING: [BD 41-1306] The connection to interface pin /microblaze_0/M_AXI_DP_AWVALID is being overridden by the user. This pin will not be connected as a part of interface connection M_AXI_DP.

This warning should be expected because the connection is no longer be included as a part of the interface, and you must manually complete the connection.

After making connections to signals or buses inside of an interface pin, you can collapse the interface to shrink the block and hide the details of the pin. Clicking on the - symbol on an expanded interface pin collapses it to hide its contents.

As seen in the following figure, the separately connected signals or buses of the interface continue to be shown as needed to properly display the connections of the BD.

Figure 2. Collapsing the Interface