DP83849IVS-EVK: Does MDI-X not work if auto-negotiation is turned off?

naotoku okamura

Prodigy 30 points

Part Number: DP83849IVS-EVK
Other Parts Discussed in Thread: DP83848I

In an environment where communication was possible with auto-negotiation,

if the communication speed is set to fixed, the link will go down.

If the DP83849IVS is set to a fixed communication speed, will MDI-X not work?

over 1 year ago

0 naotoku okamura over 1 year ago

Prodigy 30 points

>DP83848I: When auto-negotiation is disabled, can detect MDI or MIDX?

Is it the same answer as in this thread?

If possible, I would like to turn off only auto negotiation and use auto MDI/MDI-X.

Best Regards,

Okamura

0 Rahul over 1 year ago

TI__Expert 8640 points

Neither Auto-Negotiation nor Auto-MDIX is required to be enabled in forcing crossover of the MDI pairs. Forced crossover can be achieved through the FORCE_MDIX bit, bit 14 of PHYCR (19h) register.

Please refer to Section 2.2 in the datasheet:
https://www.ti.com/lit/ds/symlink/dp83849c.pdf?ts=1669669201742&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83849C

Yes, it follows same as DP83848 when force mode is not set "The Auto-MDIX algorithm requires that the Auto-Negotiation Enable bit in the BMCR register to be set. If Auto-Negotiation is not enabled, Auto-MDIX should be disabled as well. "

Please refer to the MDIX_EN description in page 65 of the datasheet.

Regards,
Rahul

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DP83849IVS-EVK: Does MDI-X not work if auto-negotiation is turned off?