Hello
Could you give me your advice about the function of ADIN1200 Polarity Inversion Correction ?
Qustion1
Is Polarity Inversion Correction done during Auto negotiation ?
Question2
How is Polarity Inversion Correction done ?
( I think that PHY of TX inverts polarity of output. for exmple MDI_0_P becomes MDI_0_N internally. Is my understanding correct ?)
Regards,
Teli
Hi Teli,
In the ADIN1200, polarity correction is applied only to 10BASE-T links, while 100BASE-TX is unaffected by polarity due to its MLT3 encoding.
Polarity inversion is detected by analyzing the sign of the 10BASE-T received signals. If the signals do not have the expected sign (where NLPs are expected to be positive pulses and the first bit of a packet, encoded in Manchester, should be a 1), they are inverted. Additionally, bit 10 of PHY_STATUS_1 is set to indicate this inversion.
Refer to the figure below, which shows a crossover cable connecting the ADIN1200 and its link partner, with the pair connected to the ADIN1200 RD MDI pins having inverted polarity.
During auto-negotiation, the polarity of FLPs is also corrected if necessary, ensuring that auto-negotiation can continue. However, the polarity of a 10BASE-T link is detected once the link is established, regardless of whether auto-negotiation is enabled.
regards,
Mark
