• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 33 subscribers
  • Views 268 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83826I: Configuring LED2 to indicate LINK status

Markus Moisio
Prodigy 10 points
Part Number: DP83826I

Hello,

We are trying to configure the DP83826I PHY to indicate link status in LED2 output. We are using it in enhanced mode and have configured to register as follows:

460h = 0x3000 -> LED2 source is LINK OK

305h = 0x0000 -> LED2 GPIO configuration is LED2

We have external pull-down on pin28 and LED2 polarity is then active HIGH. The problem is that we see no change in LED2 output of pin28 from DP83826I when we are causing link UP/DOWN events. Register shows correctly that link is established (or lost) but it is not reflected on LED2. Pin 28 should be by default be in LED2 mode as we are using RMII. For example LED0 by default is correctly showing the link status.

Have we missed something? 

Curious thing is that when we read 305h register it's value changes when cable is connected and link is up. With link up 305h = 0xcde1 and when link is down 305h = 0x0000 (as it should be, that's what we write to it in boot up). We are not writing register 305h after boot up. 

Thanks for any help I can get.

  • 0
    TI__Mastermind 24988 points

    Hi Markus,

    Can you share the schematic so I can confirm the LED layout?

    The described configuration seems correct - how are you writing registers in the extended space? Have you read the register values back to see if they match the intended configuration?

    Thank you,

    Evan

  • 0 in reply to Evan Mayhew
    Prodigy 10 points

    HI Evan,

     Thanks for your comments. We are using MDIO interface to configure the registers of the PHY. We use Renesas RZN2L processor and it has integrated MDIO master. We have read the registers back to confirm that it works. That's when we found out the strange behaviour of 305h register which changes values depending on if cable is plugged or not. All other register we read, for example link status in 001h register seem to correctly change status with the cable attached etc. So that should work.

    Below is the schematic for the led, It does not actually have a LED attached but that could not be the problem I hope.

  • 0 in reply to Markus Moisio
    Prodigy 10 points

    Problem solved. It was a missconfiguration issue after all. We were writing/reading the extended registers (>32 address) wrongly. We though that we were doing it correctly as it partly worked but after using the REGCR and ADDAR registers properly to read/write them we manged to get the LED2 working like we want.

    Thank you again, Evan.