Clocking - 2022.2 English

Vitis Networking P4 User Guide (UG1308)

Document ID
2022.2 English

The Clocking tab is shown in the following figure.

Figure 1. Clocking Tab

Values entered are used to evaluate the impact of the clock frequency on latency within the system and also for implementation.

AXI Stream Clock
Enter the AXI stream clock frequency in MHz (up to a maximum of 600 MHz). For reliable timing closure use 300 MHz or below.
CAM Memory Clock
Enter the CAM Memory Clock frequency in MHz (up to a maximum of 600 MHz). The CAM Memory Clock allows for the CAMs to run at a higher rate than the AXI Stream clock to reduce resource utilization. There are no requirements on the ratio between the two clocks, but they must both be derived from the same original clock source. The ratio between the CAM Memory Clock and the PKT_RATE parameter determines the TDM_FACTOR which can help achieve potential resource savings. Refer to the CAM product guides listed in References) for details on the TDM_FACTOR to achieve potential resource savings.