13 Replies Latest reply on Nov 20, 2017 4:23 AM by Bert_L

    I210 - unused MDI pins when configuring 100BASE-T

    Bert_L Green Belt

      I am using the I210IT in my design as a fixed 100BASE-T controller. As there are only two transformers used which are connected to MDI-0 and MDI-1, the MDI-2 and MDI-3 pins are not in use. Can I leave these unused pins open or do I have to terminate them?

        • Re: I210 - unused MDI pins when configuring 100BASE-T
          Carlos_A Brown Belt

          Hello, Bert_L:

           

          Thank you for contacting Intel Embedded Community.

           

          It is unclear for us if your design is in 1000BASE-T, 100BASE-TX, or 10BASE-T mode. However, the information that may help you is stated in the third row of Table 2-7, on page 27 of the Intel(R) Ethernet Controller I210 Datasheet document # 333016.

           

          We hope that this information may help you.

           

          Best regards,

          Carlos_A.

            • Re: I210 - unused MDI pins when configuring 100BASE-T
              Bert_L Green Belt

              Hello Carlos,

               

              Thanks for your suggestion. The design uses the 100BASE-TX mode. When following the related content in table 2-7 of the datasheet, the unused MDI pins are stated as 'unused'. Furthermore, the note in paragraph 2.3.6: 'The I210 has built in termination resistors. As a result, external termination resistors should not be used.' give me the idea that these pins can be left open. However, in paragraph 12.5.5, figure 12-12 the unused MDI pins are pulled to a supply (being +1.5V in the figure, +1.9V in the text) through 50ohm resistors so I am in doubt.

              Currently in the design the pins are open. It functions as expected but we see occasionally (e.g. once a day) that the link is lost for a short time. I was wondering if this link loss has anything to do with the unused/open MDI pins?

               

              Thanks in advance,

              Bert

                • Re: I210 - unused MDI pins when configuring 100BASE-T
                  Carlos_A Brown Belt

                  Hello, Bert_L:

                   

                  Thanks for your reply.

                   

                  They can be left as NC as long as there are no traces coming off of the pad.

                   

                  We hope that this information may help you.

                   

                  Best regards,

                  Carlos_A.

                    • Re: I210 - unused MDI pins when configuring 100BASE-T
                      Bert_L Green Belt

                      Hello Carlos,

                       

                      Thanks for your information. Unfortunately there are traces present: approx. 0.5 inch of (well-shielded) trace and a 31mil testspot for testability reason. Do you think this can cause the problem that we are chasing after (sporadic link loss?).

                       

                      Best regards,

                      Bert

                        • Re: I210 - unused MDI pins when configuring 100BASE-T
                          Carlos_A Brown Belt

                          Hello, Bert_L:

                           

                          Thanks for your update.

                           

                          In order to find a solution to this inconvenience, could you please add a 10k pull down to each of those lines and let us know the outcomes of these changes?

                           

                          Waiting for your reply.

                           

                          Best regards,

                          Carlos_A.

                            • Re: I210 - unused MDI pins when configuring 100BASE-T
                              Bert_L Green Belt

                              Hello Carlos,

                               

                              I have added 10kohm pulldown resistors on the testspots which are connected to the MDI_2_N, MDI_2_P, MDI_3_N and MDI_3_P pins. I retested the setup but unfortunately the link loss still occurs.

                              As the link loss problem only appears on the 100BASE-TX ports and not on the other 1000BASE-T ports I am doubting if the controllers are configured correctly. Which configuration setting is needed for setting the I210 to fixed 100BASE-TX?

                               

                              Best regards,

                              Bert

                                • Re: I210 - unused MDI pins when configuring 100BASE-T
                                  zygmuntturkiewicz Community Member

                                  Hello Bert,

                                                     please apply the rules as described in i210 data sheet, chapter: 12.5.5 Designing the I210 as a 10/100 Mb/s Only Device.

                                  Install the 50 ohm resistors to 1.5V rail as discussed in the data sheet if the unused MDI lines do not go to magnetics.

                                   

                                  It is also very important to disable the 1G operation as stated in the data sheet in chapter 12.5.5:

                                   

                                  1. Set bit 4 of the Software Defined Pins Control (LAN Base Address + Word 0x20) to 0b. Setting bit 4
                                  to 1b disables 1000 Mb/s (GbE) operation in all power modes.

                                   

                                  If you install the resistors and disable 1G mode, then all shall work well.

                                   

                                  Thanks,

                                  Zygmunt

                                    • Re: I210 - unused MDI pins when configuring 100BASE-T
                                      Bert_L Green Belt

                                      Hello Zygmunt,

                                       

                                      Thanks for your advice. We have installed the 50 ohm resistors as shown in figure 12-12 of the data sheet because our circuit cannot be connected to magnetics easily.

                                      Unfortunately it is not clear for us how to set bit 4 of this register in our system persistently. We have tried to change the register content in EEUPDATE as well as in LANCONF but we could not see changed results in supported link modes and advertised link modes when listing the modified NIC through (Linux) ethtool. Maybe this is due to our unfamiliarity with these tools. Or it is needed to patch the .bin file and reprogram the flash?

                                       

                                      I hope you can give us an advice how to set the bit and how to check if this is succeeded.

                                       

                                      Thanks in advance,

                                      Bert