Example 3: User-Defined Pattern with SET_DEFAULT Command - 1.0 English

AXI High Bandwidth Memory Controller v1.0 LogiCORE IP Product Guide (PG276)

Document ID
PG276
Release Date
2021-08-06
Version
1.0 English

If you have a large set of commands most of which have the same value in the columns, you can set default values to these and specify the keyword DEFAULT or leave it blank in the respective columns. In the following example, you should always send the same address 0 except in the third command where it is to a different address. Hence, specify the default address as 0 and override it to 'hA5A5_A5A5 in the third command.

You can also set the default Write and Read bandwidths. The units are specified in Mb/s. When the default bandwidth is specified, the AXI-TG internally calculates the delay to be applied between consecutive AXI transactions to achieve the specified bandwidth.

The calculation assumes an ideal AXI slave which does not apply any back pressure (All READY signals of AXI3 are always asserted). In case the slave applies back pressure, the AXI-TG does not push traffic at the specified bandwidth and the actual bandwidth is lower. You can specify either the default bandwidth or the default start_delay+intra_byte_delay (as both commands indirectly control the delay in the AXI transactions). The latest command overrides the previous command.

SET_DEFAULT Command Usage