AR# 116: XC3000/XC4000: Can I source ACLK/GCLK from internal logic? BUFGS, BUFGP?
AR# 116
XC3000/XC4000: Can I source ACLK/GCLK from internal logic? BUFGS, BUFGP?
ソリューション
Users are sometimes concerned that global buffer resources are either not accessible from internal logic, or that the use of one with internal logic forces the wasting of an input pin. The following summarizes this for the different families of FPGAs:
2k: You can source either ACLK or GCLK from internal logic at no cost, i.e. no IOB is used up.
3k: You can source either ACLK or GCLK from internal logic at no cost.
4k: You can source BUFGS from internal logic at no cost, but sourcing BUFGP internally uses up the IOB dedicated for that clock buffer.