DP83848K: Cannot connect with 100 Mbps but 10 Mbps works

Hi Rushit,

Are you sure your link partner can do 100Mbps?

Have you tried connecting to other link partners?  You can use your computer as a link partner to test out.

Kind regards,

ross 

Hi Ross,

Myself Ritesh Prajapati working with Rushit from software side for this Ethernet issue.

No, we are able to connect ethernet only on 10 Mbps speed not 100 Mbps speed and we have checked that Auto-negotiation is working fine without any issue.

Following are software details on which we are working

• Linux Kernel Version 3.8.7
• Ethernet Driver STMMAC

We have did following test-cases to check and debug Ethernet connectivity on our product board in which Ethernet cable of our board is directly connected with one Laptop using point to point direction connection and also we have installed TFTPD32 utility for DHCP server IP assignment.

Please Have a look of following tables with results which we have verified with direct P2P communication.

Test Case	Board Configuration	Leptop Configuration	Result
1	Auto negotiation	Auto negotiation	Failed
2	Auto negotiation	100 FULL	Failed
3	Auto negotiation	100 HALF	Failed
4	100 FULL	100 FULL	Failed
5	100 HALF	100 HALF	Failed
6	Auto Negotitation	10 FULL	PASS
7	Auto Negotitation	10 HALF	PASS
8	10 FULL	10 FULL	PASS
9	10 HALF	10 HALF	PASS

Please let me know if you have any idea or configurations required to be set to debug or get some clue for this type of issue and also lert me know if need any further informations from software side.

Regards,

Ritesh Prajapati

Please find attached the testing sheet which shows the Rx_DV & CRS_DV signals are different at 100 Mbps in our board but the signals are same at 10 Mbps when it is compared with ref board with same IC.

Testing.xls 

Please provide us the probable reasons for the same asap,also for your ref find below the screenshot of the same.

Hi Ross,

I have also one requirement to check this issue that do you have any type of utility or way to check loop-back test of TX and RX pins of this phy to validate it?

Please let me know if you have idea or informations for this ASAP.

Regards,

Ritesh Prajapati

Hello Ritesh,

Thanks for the detailed debug. I'm afraid I will have to ask for some more data. It looks like the PHY can auto-negotiate when link partner is forced to 10M mode. But this can also mean that the PHY in the laptop might have issue with 100M mode. Can you test link between DP83848-DP83848? Program both the DP83848K for auto-neg 10/100 and see to what speeds they link up.

Unfortunately there is no internal reverse loopback between TX and RX pins. You will have to make a external reverse loopback cable. The easiest way is to cut and rework an existing ethernet cable.

1. Cut the CAT5 cable with about 1 foot of cable and the RJ45 connector
2. Strip off about 3~4 inches of the outside plastic shield to expose the 4 pairs of twisted pair cable
3. Bend back pairs 4/5 and 7/8 (these will not be used)
4. Solder pair 1/2 to pair 3/6
1. Solder wire 1 to wire 3
2. Solder wire 2 to wire 6
5. Now you have a loopback cable.
Plug the cable into DP83848 board and link should be established (assuming Auto-Neg is enabled).

-Regards,
Aniruddha

Hi,

Thanks for quick reply and your valuable feedback.

One more update regarding 10 Mbps is that we are not getting 10 Mbps fully working as we have checked it with larger packets like 1024 byets of data transfer and we are getting some packets are dropped while testing using ping command to internal and external network.

So, it means 10 Mbps network is also not working properly as per standard Ethernet connectivity.

You are saying that do we need to test with our 2 diffent boards in what check same physical chip is used to check and validate connection like P2P connection. Correct?

We have also measured clock which we are getting proper using CRO.

Do you have any idea regarding any other toll except ethtool to debug this issue ? Any debug informations from driver perspective?

Let me know if any other way to debug the from driver or any command line tool to check in details

Hello Ritesh,

My intention is to first confirm that the problem is actually on the DP83848K board. Link issues can also come up if the Link partner has problems, in your case that would be the Laptop ethernet card.

You are correct, I meant for you to connect DP83848 with another DP83848 and see if they link in 100M. The loopback cable will allow the DP83848 to link with itself. Please post the update when you finish these two testing.

We do not have a dedicated debug tool but we do have linux driver for DP83848. You can find it here: www.ti.com/.../ethernet-sw

-Regards,
Aniruddha

Hi Aniruddha,

Thanks for your suggestions and inputs.

We have also one reference board which is Intel Galileo Gen 2 board on which same SoC as well as TI Phy are same as we are using in our development board. So, Its working fine with 10 Mbps and 100 Mpbs with Negotiation and without negotiation into that reference board.

We have also did some test-cases with direct DP83848K board to DP83848K board and cross cable and faced same issues like its not working into 100 Mbps speed and its working on 10 Mbps speed but with some errors while checking using ping requests with large packets.

Please find following tables in which I have included all possible test-cases with DP83848K board to DP83848K board and with reference board as well in which its working fine without any issue.

Test Case

	Board 1 Details	Board2 Details	Result(Ping Test)
Test1	auto negotiation ON	auto negotiation ON	OK. without packet loss
	Referrence Board 1 (Intel Galileo Gen 2 board)	Referrence Board 2 (Intel Galileo Gen 2 board)
	Automatic speed will set 100Mbps Full Duplex	Automatic speed will set 100Mbps Full Duplex
Test2	auto negotiation ON	auto negotiation ON	Failed
	Referrence Board 1 (Intel Galileo Gen 2 board)	OUR Developed Board1
	Automatic speed will set 100Mbps Full Duplex	Automatic speed will set 100Mbps Full Duplex
Test3	SET Speed 10Mbps	auto negotiation ON	OK. without packet loss
	Referrence Board 1 (Intel Galileo Gen 2 board)	Referrence Board 2 (Intel Galileo Gen 2 board)
	Speed will set 10Mbps Full Duplex	Automatic Speed will set 10Mbps half Duplex
Test4	SET Speed 10Mbps	auto negotiation ON	OK but some packets was missed
	Referrence Board 1 (Intel Galileo Gen 2 board)	OUR Developed Board1
	Speed will set 10Mbps Full Duplex	Automatic Speed will set 10Mbps half Duplex

Let me know if you need any more informations or want to test with any other test-cases.

Regards,

Ritesh Prajapati

Hi Aniruddha,

Do you need any extra informations from my side or its enough informations for you?

Regards,

Ritesh Prajapati

Hello Ritesh,

Would you be able to share the schematics with us?

-Regards,
Aniruddha

Please find attached the schematic of our processor ,PSU,PHY IC & Connector, share your views on it1778.ethernet schematic.pdf.

I will be happy if you can review it with layout, please share your email id (to share layout files).

Thanks in advance for your concern.

Regards,

Rushit6560.ethernet schematic.pdf

Hi Aniruddha,

Rushit has shared Ethernet Interface with Intel Quark x1000 SoC in previous reply. So, Please let us know if you need any other informations apart from that section to verify or to get any clue for Ethernet Interface.

Let us know your suggestions or inputs after reviewing attached schematic which is shared by Rushit.

Regards,

Ritesh Prajapati

Hi Aniruddha,

Any update regarding Ethernet issue? Have you reviewed Schematic shared by Rushit?

Let me know if you have any update or clue for that

Regards,

Ritesh Prajapati

Hi Ritesh,

I have looked at the schematic and nothing stands out as incorrect.
One thing i am curious to see though is how your MDI (cable side) signaling looks.
Can you show me the following:
1. Fast Link Pulse Burst during auto-negotiation
2. Single link pulse when PHY is forced into 10Mbps operation
3. 100Mbps (MLT3 signaling) with infinite persistence enabled. I want to see the eye opening.

For all of these, please use a 100 ohm termination cable.
Search for 'Analog loopback terminations' on page 10.
Example of termination cable:
www.ti.com/.../snla266.pdf

Kind regards,
Ross