DP83869HM: MDC preamble and transaction interval in SMI

Toshihiro Watanabe

Genius 10235 points

Part Number: DP83869HM

Hello,

1) In datasheet figure 4, there is Powerup timing chart.

T2 is "Powerup to SMI ready: Post power-up stabilization time prior to MDC preamble for register access"

Does MDC preamble mean 32 MDC clocks?

In MDC preamble period, do we need to send data via MDIO pin?

2) The customer use SMI and only one PHY loaded on SMI. I think we need to follow Figure 28 and 29.

How long we should wait for next read/write after previous read/write done? One clock idle needed or can communicate without idle period?

Best regards,

Toshihiro Watanabe

over 5 years ago

0 Vibhu Vanjari over 5 years ago

TI__Genius 11900 points

Hello Toshihiro-san,

1) Yes, if you look at that figure you will see that after T2 there are 32 MDC clocks. Yes, we do need to send the preamble to the PHY via the MDIO pin.

2) Yes, please follow those figures. Please allow the idle to be two MDC clock cycles between read/write SMI commands.

Thanks,

Vibhu

0 Toshihiro Watanabe over 5 years ago in reply to Vibhu Vanjari

TI__Genius 10235 points

Hello Vibhu-san,

Regarding 1), we need to send preamble via MDIO. What data should we send as preamble?

Best regards,

Toshihiro Watanabe

0 Toshihiro Watanabe over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 10235 points

Hello Vibhu-san,

I think we need to send preamble data while sending 32 MDC clocks.

Could you let us know what data we should send?

Best regards,

Toshihiro Watanabe

0 Vibhu Vanjari over 5 years ago in reply to Toshihiro Watanabe

TI__Genius 11900 points

Hello Toshihiro-san,

32 bits all 1s on MDIO along with MDC.

Thanks,

Vibhu

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DP83869HM: MDC preamble and transaction interval in SMI