DP83848I: Scrambler Bypass Option

Takahiro Ogo

Part Number: DP83848I
Other Parts Discussed in Thread: DP83849I,

Hi,
I have just one question.

My customer want to disable Scrambler function of DP83848I and DP83849I for their 100base test.
#Sorry, I mistook the device number in previous post. My customer are using both.

Can DP83848I/DP83849I bypass the Scrambler by setting any register?

I think DP83848I have a method to bypass the scrambler.
According to the DP83848I datasheet, "Scrambler block (bypass option)" is writtne on it.
Also, on page 49, there is a SCRAM_BYPASS bit in PCSR register of Table 6-8. Register Table.

But, on page 62, there is no SCRAM_BYPASS bit in PCSR register.

Can we use Scrambler Bypass Option? My customer want to use it.

Best Regards,
Taka

over 8 years ago

0 Rob Rodrigues over 8 years ago

TI__Mastermind 19780 points

Hi Taka-san,

What test is your customer trying to perform? Is this a compliance test that requires special outputs from the PHY? If yes, then please see this post about outputting special sequences from the PHY.

e2e.ti.com/.../491013

Best Regards,

0 Takahiro Ogo over 8 years ago in reply to Rob Rodrigues

Genius 5940 points

Hi Rob-san,
Thank you for your reply.

This is not a compliance test. Currently, communication error between DP83848/9 and other PHY(Microchip) has occurred.
They think there is a problem with Jitter between them. So, they want to output the data which is not encrypted and measure the Jitter.

Best Regards,
Taka

0 Rob Rodrigues over 8 years ago in reply to Takahiro Ogo

TI__Mastermind 19780 points

Hi Taka-san,

If this is debug, then they can try to use the scrambler bypass bits. I do not have data on why the bit was reserved in the datasheet.

You can also perform compliance testing on the DP83848 and Microchip part to make sure they meet the IEEE defined TX jitter tolerance.

Best Regards,

Interface

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DP83848I: Scrambler Bypass Option