DP83848J: Not getting link when connected to a 1Gbps router. Most times with a 100 Mbps switch it properly works

Matteo Ghittorelli

Part Number: DP83848J

We develop an IoT gateway based on ESP32 + DP83848J as PHY for ehternet. The PHY is working properly getting the link when connected to a 100 Mbps switch. If we directly connect the Ethernet to a modem router (or some switches) it does not get the link. We already tried to fix the PHY speed and duplex mode, and disabling autonegotiation.

In this case we get the link with most of the routers (only at 10 Mbps) but then the ARP messages result corrupted and we are not able to properly get the IP from the router.

We produced 10 devices and not all of them show the same problem with the same network device (router/switches).

We made several tests and the strapping is OK, Voltages on PFB and RBIAS are OK.

Can someone give us some guidance how to proceed?

Thanks a lot

over 2 years ago

+1 Melissa Chang over 2 years ago

TI__Genius 14005 points

Hi Matteo,

Thank you for reposting this in a new thread. For personal reference, I will link your previous thread here: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1224989/dp83848j-not-getting-link-when-connected-to-a-router-most-times-with-a-100-mbps-switch-it-properly-works

I have a few tests for you to try:

- Could you provide a scope shot of your MDI signal? The fact that lower data rates are able to link make me wonder if the issue lies in the quality of the signal. There are instructions for how to do this in this app note in section 3.4.7: https://www.ti.com/lit/an/snla246b/snla246b.pdf?ts=1692927342776&ref_url=https%253A%252F%252Fwww.google.com%252F

- Could you also try the following test:

Enable loopback mode by setting the LOOPBACK bit of BMCR register to 1
(Optional) Set the bit PSR_15 in PHYCR to use 15 bit pseudo random sequence, instead of the default 9 bit sequence
Start the BIST by setting the BIST_START bit of PHYCR register to 1
Read the results by reading the BIST_STATUS bit of PHYCR, to check whether it is a 1(pass) or 0(fail)

Additionally, what do you mean by the ARP messages are corrupted? What do the corrupted messages look like compared to the original messages?

Best regards,

Melissa

0 Matteo Ghittorelli over 2 years ago in reply to Melissa Chang

Prodigy 20 points

We finally found the problem in the ethernet connector, by changing this component all the devices became working.

Thanks a lot for the support

0 Melissa Chang over 2 years ago in reply to Matteo Ghittorelli

TI__Genius 14005 points

Hi Matteo,

I'm glad to hear it works now! Would you be able to elaborate on the connector issue? Was it a specific part number that does not work with our device? What is the new part number?

Best regards,

Melissa

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DP83848J: Not getting link when connected to a 1Gbps router. Most times with a 100 Mbps switch it properly works