ilinx的7 series fpga transceivers wizard用於自定義的serdes編碼。
要選擇多個serdes端口，如下圖，點擊對應的名稱，然后右邊選擇use該設備就可以。
生成后example文件中的support GT_USRCLK_SOURCE 文件，有個時鍾文件。打開了悲劇了。所以經常debug調試，用其他的接收的時鍾，無緣無故的出現no arm clk。實在是火大。
module k7_serdesx8_GT_USRCLK_SOURCE 這個文件
BUFG txoutclk_bufg0_i
(
.I (gt0_txoutclk_i),
.O (gt0_txusrclk_i)
);
BUFG rxoutclk_bufg1_i
(
.I (gt0_rxoutclk_i),
.O (gt0_rxusrclk_i)
);
assign GT0_TXUSRCLK_OUT = gt0_txusrclk_i;
assign GT0_TXUSRCLK2_OUT = gt0_txusrclk_i;
assign GT0_RXUSRCLK_OUT = gt0_rxusrclk_i;
assign GT0_RXUSRCLK2_OUT = gt0_rxusrclk_i;
assign GT1_TXUSRCLK_OUT = gt0_txusrclk_i;
assign GT1_TXUSRCLK2_OUT = gt0_txusrclk_i;
assign GT1_RXUSRCLK_OUT = gt0_rxusrclk_i;
assign GT1_RXUSRCLK2_OUT = gt0_rxusrclk_i;
assign GT2_TXUSRCLK_OUT = gt0_txusrclk_i;
assign GT2_TXUSRCLK2_OUT = gt0_txusrclk_i;
assign GT2_RXUSRCLK_OUT = gt0_rxusrclk_i;
assign GT2_RXUSRCLK2_OUT = gt0_rxusrclk_i;
assign GT3_TXUSRCLK_OUT = gt0_txusrclk_i;
assign GT3_TXUSRCLK2_OUT = gt0_txusrclk_i;
assign GT3_RXUSRCLK_OUT = gt0_rxusrclk_i;
assign GT3_RXUSRCLK2_OUT = gt0_rxusrclk_i;
辦法就是自己增加代碼，使用bufg模式，引出其他的時鍾。代碼如下：
BUFG txoutclk_bufg0_i
(
.I (gt0_txoutclk_i),
.O (gt0_txusrclk_i)
);
BUFG rxoutclk_bufg0_i
(
.I (gt0_rxoutclk_i),
.O (gt0_rxusrclk_i)
);
////////////////////////////////1
BUFG txoutclk_bufg1_i
(
.I (gt1_txoutclk_i),
.O (gt1_txusrclk_i)
);
BUFG rxoutclk_bufg1_i
(
.I (gt1_rxoutclk_i),
.O (gt1_rxusrclk_i)
);
////////////////////////////////2
BUFG txoutclk_bufg2_i
(
.I (gt2_txoutclk_i),
.O (gt2_txusrclk_i)
);
BUFG rxoutclk_bufg2_i
(
.I (gt2_rxoutclk_i),
.O (gt2_rxusrclk_i)
);
////////////////////////////////3
BUFG txoutclk_bufg3_i
(
.I (gt3_txoutclk_i),
.O (gt3_txusrclk_i)
);
BUFG rxoutclk_bufg3_i
(
.I (gt3_rxoutclk_i),
.O (gt3_rxusrclk_i)
);
assign GT0_TXUSRCLK_OUT = gt0_txusrclk_i;
assign GT0_TXUSRCLK2_OUT = gt0_txusrclk_i;
assign GT0_RXUSRCLK_OUT = gt0_rxusrclk_i;
assign GT0_RXUSRCLK2_OUT = gt0_rxusrclk_i;
assign GT1_TXUSRCLK_OUT = gt1_txusrclk_i;
assign GT1_TXUSRCLK2_OUT = gt1_txusrclk_i;
assign GT1_RXUSRCLK_OUT = gt1_rxusrclk_i;
assign GT1_RXUSRCLK2_OUT = gt1_rxusrclk_i;
assign GT2_TXUSRCLK_OUT = gt2_txusrclk_i;
assign GT2_TXUSRCLK2_OUT = gt2_txusrclk_i;
assign GT2_RXUSRCLK_OUT = gt2_rxusrclk_i;
assign GT2_RXUSRCLK2_OUT = gt2_rxusrclk_i;
assign GT3_TXUSRCLK_OUT = gt3_txusrclk_i;
assign GT3_TXUSRCLK2_OUT = gt3_txusrclk_i;
assign GT3_RXUSRCLK_OUT = gt3_rxusrclk_i;
assign GT3_RXUSRCLK2_OUT = gt3_rxusrclk_i;
這樣每個端口發送和接收的時鍾都是獨立的。如果不是這么設定，那個可能多個端口接收時鍾不一樣就完蛋