DP83867IR: CRC error in MII mode

Lin_Charles

Part Number: DP83867IR
Other Parts Discussed in Thread: DP83867E

Hi team,

My customer is using DP83867IR in their current design. Schematic has been review by team before. When they do MII loopback, they find that in 1000M mode, no CRCerror. While in 100M mode, they can find 0.1% data loss. Could you please help suggest some methods to identify the root cause? Thanks.

BR,

Charles Lin

over 5 years ago

0 Cecilia Reyes over 5 years ago

TI__Genius 9920 points

Hi Charles,

Some items to review would be the input clock quality. Could you confirm it is withing the PPM spec we recommend?

Can you also share with me the cable length you are using?

Thanks,

Cecilia

0 Lin_Charles over 5 years ago in reply to Cecilia Reyes

TI__Expert 4260 points

Hi Cecilia,

Thank you for your help here. For the clock quality, Customer have 6 PHY in their system, they all use FPGA to generate clock,

2 using RGMII are good for 100M/1000M communication. They think clock quality will not be an issue.

While 3 of 4 DP83867E failed in 100M loopback test, 0.1% data rate. Could you please help check below questions from customer,

1.What may cause 100M data rate have 0.1% CRC error? While 1000M is all ok?

2. For the cable length, which cable length do you mean here. From RJ45 to test euipment?

3. Any other methods to find the root cause?

Thank you for your help here.

Port	Interface	Data rate	Loopback	Result
ETH1	RGMII	100/1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH2	RGMII	100/1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH3	SGMII	100/1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH4	SGMII	1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH4	SGMII	100Mbps	MAC loopback: Good Reverse loopback: Good MII loopback: Bad, crc error, data error rate 0.1%	Bad
ETH5	SGMII	1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH5	SGMII	100Mbps	MAC loopback: Good Reverse loopback: Good MII loopback: Bad, crc error, data error rate 0.1%	Bad
ETH6	SGMII	1000Mbps	MAC Loopback, MII loop back, Reverse loopback	Good
ETH6	SGMII	100Mbps	MAC loopback: Good Reverse loopback: Good MII loopback: Bad, crc error, data error rate 0.1%	Bad

BR,

Charles Lin

0 Cecilia Reyes over 5 years ago in reply to Lin_Charles

TI__Genius 9920 points

Hi Charles,

That is correct we are referring to the rj45 cable and it is for anything less than 1m of cables.

Register DSP Feedforward Equalizer Configuration (DSP_FFE_CFG), Address 0x012C of the datasheet has more information in regards to this

That is a typical issue we see occurring with CRC errors

Thanks,

Cecilia

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DP83867IR: CRC error in MII mode