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Original question:

DP83848I : PHY - Test with BIST mode

DP83849IF: BIST in external loopback

Yash Naik
Prodigy 230 points

Part Number: DP83849IF

Hi,

I have gone through the below post/thread for testing BIST in external loopback.

https://e2e.ti.com/support/interface/f/138/p/225948/805414

I did BIST in external loopback using loopback cable by following below steps in firmware:

1. Set the LOOPBACK bit of BMCR register to 1 

2. Set the BIST_START bit of PHYCR registe to 1

3 Then read the BIST_STATUS bit of PHYCR, to check whether it is a 1(pass) or 0(fail)

The BIST_STATUS bit of PHYCR shows 1-pass.

Are all the above steps to test BIST in an external loopback correct? , or do I need to enable PMD_LOOPBACK bit in RBR register?

Many Thanks.

Yash

  • 0
    TI__Genius 11725 points

    Hi Yash,

    The special cable described in the thread you linked is for external loopback. PMD_loopback, setting the RBR register, is not required for your testing. 

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    Prodigy 230 points

    Hi,

    Does that mean I only need to enable the BIST bit and not the internal loopback bit-LOOPBACK bit of BMCR register?

    I did BIST in external loopback using loopback cable by following below steps in firmware:

    1. Set the LOOPBACK bit of BMCR register to 1 

    2. Set the BIST_START bit of PHYCR registe to 1

    3 Then read the BIST_STATUS bit of PHYCR, to check whether it is a 1(pass) or 0(fail)

    The BIST_STATUS bit of PHYCR shows 1-pass.

    Are all the above steps to test BIST in an external loopback correct?

  • 0 in reply to Yash Naik
    TI__Genius 11725 points

    Hi Yash,

    Yes that is correct, LOOPBACK bit enables MII loopback, loopback between the MAC and PHY. Refer to 5.7 for additional information.

    Thank you,

    Nikhil