AM623: RGMII internal delay question

Dear,

I discovered that there is a delay in the transmission clock and data of am623 when measuring RGMII. We made sure that the internal delay was not activated on the phy side, however, the datasheet of am623 mentioned that "TXC is delayed internally before being driven to the RGMII[x]_TXC pin." It also stated that "This internal delay is always enabled". I would like to inquire if the delay is automatically turned on if no input is given, and if so, what is the default delay time?

Thanks for your help.

Best regards,

Tommy

Shine：

 internal delay是一直使能的。没有具体的delay时间值，请看下面的帖子。https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1292438/am625-rgmii-internal-transmit-delay-selection/4905992

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Lin Tommy：

Dear,

The answer is "There is no exact delay value. The min delay is provided in the data sheet". What is the minimum delay time value for AM623?

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Shine：

1.2ns, 请看数据手册上的表Table 7-37. RGMII[x]_TD[3:0] and RGMII[x]_TX_CTL Switching Characteristics – RGMII Modehttps://www.ti.com/lit/ds/symlink/am625.pdf

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Lin Tommy：

Hi Shine,

According to our measurement, the delay time appears to be 2ns.

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Shine：

请问具体有什么问题？

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Lin Tommy：

Hi Shine,

You mentioned that the minimum delay time value for AM623 is 1.2ns (according to datasheet table 7-37), but our measurement value seems to be 2ns.

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Shine：

最小值是1.2ns, 2ns大于等于1.2ns正常。

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Lin Tommy：

Hi Shine,

May I confirm that the internal delay value for AM623 is 2ns, rather than the minimum value of 1.2ns?

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Shine：

上面e2e的帖子里工程师回复了，没有特定的值。There is no exact delay value. The min delay is provided in the data sheet"

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Lin Tommy：

Hi Shine,

Does "There is no exact delay value" mean that the delay time varies for each component?

Why is there no precise delay time?

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Shine：

是的，这可能是芯片内部的设计。

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Lin Tommy：

Hi Shine,

Thank you for your response.

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Shine：

不客气~