DP83TC811R-Q1: DP83TC811RWRNDRQ1

Hi Yigal,

This might be a typo but you mentioned that EN and WAKE pins are used as output however they are input pins to the PHY. Your schematics shows the correct signal direction on the EN and WAKE pin but I would like to confirm that you are using EN and WAKE pin as inputs to the PHY. 

Next, you are sending a negative pulse on the RESET pin. How long is this negative pulse? Can you check that RESET pin is back to the correct VDDIO voltage once the reset pulse has completed?

Can you also probe pin 16 CLKOUT pin of the PHY to check that there is clock output? If you have the ability to read registers please try reading registers 0x0002 and 0x0003 of the PHY to check if you are getting the same values as mentioned in the datasheet?

-Regards

Aniruddha

Hi Anirudha,

Finally i got the 25Mhz clock working , after EN and WAKE is set the clock start running.

Now i have another problem.

I'm working with Analog Devices ADSP-SC584 Sharc device.

Previously we worked with EVAL ADSP-SC584 EZ BOARD .

On this EVAL we worked with BCM89810 PHY (broadcom). We are using lwIP TCP stack library.

For some reason when i start the MAC i get PHY initialization failure. 

I checked the EMAC settings on DSP . Everything is set for RGMII mode.

Are there any difference in basic PHY initialization between the broadcom PHY and TI PHY (both automotive)

Please Advice.

Hi Yigal,

Glad to hear that your initial issue was resolved. For the next question, it is reasonable to expect differences between Broadcomm PHY and TI PHY initialization. However, I will only be able to comment from the TI PHY perspective. Can you share more details about the initialization error that you are seeing? What exact errors are you seeing on your board? 

Also, we have a dedicate Linux Driver for DP83TC811. Can you check if you are using the TI linux driver?

-Regards

Aniruddha

Hi Anirudha,

Finally the PHY is working.

I have a last question:

For some reason i can't leave the RX_D2 pin unstrapped.

If it is strapped to work in RGMII mode it works fine after i configure both TX and RX Delay on.

If it is not strapped even if i reconfigure the xMII_CTRL Register (0x0017 ) over Serial Interface it does not work.

Please Advice.

Hi Anirudha,

Finally the PHY is working.

I have a last question:

For some reason i can't leave the RX_D2 pin unstrapped.

If it is strapped to work in RGMII mode it works fine after i configure both TX and RX Delay on.

If it is not strapped even if i reconfigure the xMII_CTRL Register (0x0017 ) over Serial Interface it does not work.

Please Advice.

Hi Yigal,

When you leave it unstrapped, what is the voltage on RX_D2 pin during power up? Maybe the processor has internal straps that are affecting the voltage the PHY reads on RX_D2.

-Regards

Aniruddha

Hi Aniruddha,

When the RX_D2 is unstrapped it is set in MODE 1 - (00) meaning no PU or PD connected.

This is illegal state for  MAC interface Selection Bootstraps Table 20 in the datasheet.

MAC[2] -0  MAC[1] -0 MAC[1] -0  is RGMII reserved state (if PU is connected to RX_D2 pin it will set RGMII Alighn mode state).

As i understand the strapping is sampled by the PHY only during Power up or Hardware Reset and it can be changed by writing to the PHY registers over serial interface.

 There is xMII_CTRL Register (0x0017) in the PHY and i write to it and set it to work in RGMII mode and read it back for verification it seems that it is configured but still does not work.

Please Advise.

Hi Yigal,

Yes, MAC [2:0] is a reserved state but what I want to confirm is if the MAC that you are using has any internal pull resistors. You mentioned that when you leave it with no straps the PHY doesn't work. It is possible that the MAC has internal pull resistors that will cause incorrect voltage on the RX_D2 pin causing the PHY to enter into a incorrect mode.

When RX_2 pin is left floating and the PHY does not work, can you still read registers? Can you try reading register 0x467? This register will contain the status of the PHY strap pins.

-Regards

Aniruddha

Hi Aniruddha,

I can read the register and i see that the strapping is in RX_D2 Bootstrap mode1 (00) that means MAC Interface reserved state (Table 20 in datasheet).

Hi Yigal,

In this case, I think the PHY is strapping as per expected. You will need to add pull up resistor on RX_D2 to put it in strap mode 4. This way RGMII Align mode will be activated assuming RX_D1 and RX_D0 are left open.

-Regards

Aniruddha