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IMXRT: option to configure delay in RMII path

Question asked by Geo Varghese on Jun 19, 2018
Latest reply on Jun 26, 2018 by Artur Petukhov

We are using IMXRT1051 in one of our design which is interfaced with an Ethernet switch IP175D using RMII. We are facing an issue here. The packets from IMXRT to external PC via the IP175D switch reaches fine. But when we are trying to send packet from external PC to the IMXRT, the data packet received is having CRC error.

 

We tried the following with Ethernet interface.

  • Configured imxrt ENET_REF_CLK as input to receive reference clock from IP75D switch. Then we connected the RMII1_MAC_CLK_OUT(50MHz RMII clock out) of switch to GPIO_B1_10 pin of IMXRT to receive 50MHz RMII reference clock. With this configuration we are getting CRC error on packets received at the IMXRT.
  • Configured iMXRT ENET_REF_CLK as RMII reference clock out. Then we connected the RMII1_MAC_CLK_IN(RMII CLK IN) of switch to GPIO_B1_10 pin of IMXRT to receive the 50MHz RMII reference clock. With this configuration also we are getting CRC error on packets received at the IMXRT.

We are assuming that there is issue in timing between the TX of the switch and RX side of the IMXRT. Is there any register option to configure delay in RMII RX side of IMXRT?

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