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DP83826E: KSZ8081MNX/RNB to DP83826 System Rollover - LED1 configuration

Leonardo Costa
Prodigy 20 points
Part Number: DP83826E

Hello,

i'm following the SNLA338 document in order to support the DP83826 physical controller in a firmware already supporting the KSZ8081. But i have a problem configuring the LED1 output pin. I noticed a mismatch between the SNLA338 document and the DP83826E datasheet:

- SNLA338 pag. 3 par. 2.6 , "Program register 0x0460 with 0x0001 for the LED to stay high OR register 0x0460 with 0x0008 for a blinking LED"

- DP83826E, pag. 86 par. 9.5.75, "Bit 15-12 LED1 Control"

in the first document the first 4 bits of the 0x0460 register are specified for the LED1 configuration, but those bits in the second document are tagged as "RESERVED" while tha last 4 bits are tagged as "LED1 Control" and they are also tagged as Read Only. So the LED1 cannot be configured. I tried to write the last 4 bits of the 0x0460 register and they actually are Read Only. If i write  the first 4 bits as specified in the first document i see a change in the LED1 behaviour, but not as expected. I need an Activity blinking led, with a blinking frequency as configured in the 0x0018 register, on LED1 pin in order to be compliant with the firmware supporting the KSZ8081.

Best Regards,

Leonardo Costa

  • 0
    TI__Mastermind 39755 points

    Hi Leonardo,

    I am checking with the team regarding this.

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    TI__Mastermind 39755 points

    Hi Leonardo,

    This appears to be a typo on our datasheet. We will look to correct it in upcoming revisions. You may confirm the following in your testing:

    - [15:12] is Reserved

    - [11:8] is LED3 control

    - [7:4] is LED2 control

    - [3:0] is LED1 control

    Sincerely,

    Gerome

  • 0 in reply to Gerome Cacho
    Prodigy 20 points

    Hello,

    thanks for the reply. Now i'm using the [3:0] bits for the LED1 control, but i can only switch between LINK OK and LINK OK/BLINK on TX/RX Activity functions. If i write 8h i get the LINK OK/BLINK on TX/RX Activity function, otherwise for any other number i get the LINK OK function.

    Best Regards,

    Leonardo

  • 0 in reply to Leonardo Costa
    TI__Mastermind 39755 points

    Hi Leonardo,

    Can you give me a register log of you programming the bitfield in different modes, as well as readbacks on that Reg 460 to confirm your writes are being accepted? Is the bitfield not changing outside of [3] and therefore is only working to be between 0x0 and 0x8? Or is the bitfield changing and the LED not acting the way you intend for it to be? Have you scoped this pin out to determine that the LED is changing in different ways between modes? What are your intended modes you want to do in your final application?

    Sincerely,

    Gerome