Clocking

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GEM requires the following clocks:

Table 1. Transmit Clock Frequencies
MAC Speed Mode (Mbps) gtx_clk (MHz) tx_clk (MHz)
SGMII GMII SGMII MII
10 125 N/A 1.25 2.5
100 125 N/A 12.5 25
1000 125 125 125 125

The following table lists the required frequencies of the receive clock.

Table 2. Receive Clock Frequencies
MAC Speed Mode (Mbps) pcs_rx_clk (MHz) rx_clk (MHz)
SGMII GMII/MII SGMII GMII/MII
10 125 N/A 1.25 2.5
100 125 N/A 12.5 25
1000 125 N/A 62.5 125

For more information about GEM Clocking, see PolarFire FPGA and PolarFire SoC FPGA Clocking Resources User Guide .