EBAZ4205 PL时钟
EBAZ4205默认的PL时钟是没有连接的，又不想每次都用PS分时钟出来给PL使用。
群里有同志说用网口的晶振即可，短接R1485：
对应FPGA管脚U18
管脚约束
#led
set_property PACKAGE_PIN W13 [get_ports {led_b}]
#set_property PACKAGE_PIN W14 [get_ports {led_r}]
set_property IOSTANDARD LVCMOS33 [get_ports {led_b}]
#set_property IOSTANDARD LVCMOS33 [get_ports {led_r}]
set_property PACKAGE_PIN U18 [get_ports {clk_pl}]
set_property IOSTANDARD LVCMOS33 [get_ports {clk_pl}]