P1021/P1012 Ethernet (eTSEC) Specific FAQs

Document created by Omar Cruz Lopez Employee on Aug 6, 2012Last modified by Omar Cruz Lopez Employee on Aug 6, 2012
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For P1021 eTSEC, can I connect eTSEC RGMII with other vendor CPU/FPGA which also supports RGMII Ethernet MAC? In other words, the other side of eTSEC is not a PHY, but a MAC.

You can definitely do that but you should remember to connect TX signals of P1021 to RX signals of another MAC and vice versa for MAC mode RGMII as shown below: P10xx_TXD [0:3] -> FPGA_RXD [0:3] P10xx_TX_CTL->FPGA_RX_CTL P10xx_TX_CLK->FPGA_RX_CLK P10xx_RXD [0:3]<-FPGA_TXD[0:3] P10xx_RX_CTL<-FPGA_TX_CTL P10xx_RX_CLK<-FPGA_TX_CLK Also, you have to take the clock delay into consideration.

If I didn’t use RGMII, can MDIO/MDC and LVdd be configured at 3.3V for P1012/P1021?

The LVdd bank can be operated at 2.5V (for RGMII) and 3.3V(MII/RMII). All the eTSEC IOs including MDIO and MDC can operate at both the voltages.

I measured the rise/fall time for RMII interface (800ps) to be lower than P1012/P1021 hardware Spec requirement (min 1ns). Is that a problem? How can I rectify it?

When a requirement/condition is specified in hardware spec, it means that we test/guarantee our device to work at that particular condition.

For RMII, the hardware spec is inherited from the RMII spec, which states that the rise and fall time should be from 1ns to 5ns. The reason behind is that the RMII spec wants to simplify the layout requirement such that no termination or impedance matching is needed.

Although it can be said that a faster rise/fall time is not likely to cause a failure, in order to meet the hardware spec and/or the RMII spec, below steps are recommended:

1. match impedance and add serial termination for the CLK, or 2. use a slower CLK source

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