AR# 438: SYNOPSYS - XNFPREP issues ERROR 3673, due to multiple clock buffers inserted.
AR# 438
SYNOPSYS - XNFPREP issues ERROR 3673, due to multiple clock buffers inserted.
Description
Keywords: Synopsys, XNFPREP, Error3673, global buffers
Urgency: Standard
General Description: The FPGA Compiler and the Design Compiler are capable of automatically inserting global buffers (BUFG) on clock nets and high fan-out nets. However, a problem lies in the number of global buffers that get inserted, as the compiler may insert more global buffers than are available on the device. This causes XNFPREP to terminate with Error Message 3673.
Solution
To avoid the excessive use of global buffers on clock nets, explicitly define which ports are clock ports. Do this by declaring that all ports are "not clock" ports; then, define which ports are indeed clock ports.