下面是 EMAC 的RX_CLK, TX_CLK的输出，为什么要加DDR LOGIC，注释看的不太明白
// Drive client clocks off chip
// DDr logic is used for this purpose to ensure that clock routing/timing to the pin is
// balanced as part of the clock tree
assign not_rx_clk_int = ~(rx_clk_int);
assign not_tx_clk_int = ~(tx_clk_int);
ODDR2 rx_clk_ddr (
.Q (rx_clk),
.C0 (rx_clk_int),
.C1 (not_rx_clk_int),
.CE (1'b1),
.D0 (1'b1),
.D1 (1'b0),
.R (reset),
.S (1'b0)
);
ODDR2 tx_clk_ddr (
.Q (tx_clk),
.C0 (tx_clk_int),
.C1 (not_tx_clk_int),
.CE (1'b1),
.D0 (1'b1),
.D1 (1'b0),
.R (reset),
.S (1'b0)
); |
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