DP83TG720R-Q1: link up time

Chuqiang Wen

Part Number: DP83TG720R-Q1

Hi Expert,

My customer have some questions regarding to the linkup time between PHY to PHY. The background is the OEM has performance requirement for linkup time. The OEM want that the time to establish a link shall be less than 100 msec after ECU wakeup, and customer's products need to use Slave Mode.

Cusomer has some investigate for the link up time. Customer use CanOE for Ethernet testing. I found that if they set CanOE to slave mode, and set DP83TG720R-Q1 to master mode, link up time is stable.

If they set CanOE to master mode, and set DP83TG720R-Q1 to slave mode, link up time is unstable. You can see the start up waveform for DP83TG720R-Q1 master mode.

Question:

They measure the linkup time by between reset signal and GPIO_0 link status. Do you think this is a proper way for linkup time?
If not, please suggest the proper way to measure the linkup time.
Why the linkup time is different between slave mode and master mode of 720?

Thanks!

Ethan Wen

over 3 years ago

0 Alvaro (Al-vuh-roe) Reyes over 3 years ago

TI__Mastermind 19621 points

Hi Ethan,

The procedure to measure linkup time is as follows:

Step 1: Follow power up sequence as per DS

Step 2: After the RESET is released, load the initialization register configuration into the PHY (as per app note:

https://www.ti.com/lit/an/snla371a/snla371a.pdf?ts=1660930587581&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDP83TG720R-Q1

)

Step 3: Start the link up time measurement and wait for GPIO_0 to toggle for link status.

Regards,

Alvaro

0 Chuqiang Wen over 3 years ago in reply to Alvaro (Al-vuh-roe) Reyes

TI__Expert 5815 points

Hi Alvaro,

Thanks for your detailed reply.

Does customer need to config all the registers to the optimized value?
I saw a testing IOP in this app note. It says the link-status is indicated by bit 15 of register 0x180. So this bit of 0x180 is match with the GPIO_0 status?
The link up time after RESET should be refer to the T6.5 which shows as below, correct?

Regards,

Ethan Wen

0 Alvaro (Al-vuh-roe) Reyes over 3 years ago in reply to Chuqiang Wen

TI__Mastermind 19621 points

Hi Ethan,

Does customer need to config all the registers to the optimized value?
- Yes, we recommend them as a minimum requirement
I saw a testing IOP in this app note. It says the link-status is indicated by bit 15 of register 0x180. So this bit of 0x180 is match with the GPIO_0 status?
- Yes, it should match.

The link up time after RESET should be refer to the T6.5 which shows as below, correct?
- It'll be this 1.5 ms + whatever time it takes to link up
  - Link up time is measured after the PHY is ready
    - i.e. after the recommend settings/configuration is loaded (not after RESET)

Regards,

Alvaro

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DP83TG720R-Q1: link up time