DP83867CS: Always the same value when reading via MDIO

Mario Bernhard

Part Number: DP83867CS
Other Parts Discussed in Thread: USB-2-MDIO

Hello,
on a customer-specific board is a DP83867CS to a LS1012A connected. It is the only PHY at this MDI (MDIO) bus. When reading the register (Status, PHYIDR1, PYHIDR2,...) I always get a response the value 0x9B19.
It is possible that this is a kind of error code ?

Best regards,

Mario

over 5 years ago

0 Geet Modi over 5 years ago

TI__Mastermind 26320 points

Hi,

Do you have pull-up on MDIO ?
Have you tried using MDIO-USB tool provided by TI ?

Regards,
Geet

0 Mario Bernhard over 5 years ago in reply to Geet Modi

Prodigy 80 points

Hello,

I have done it with PULL-UP 2.2k and 4.7k and without tested - no change.

USB-2-MDIO i didn't use since I'm neither an MSP430 LounchPad still a windows.

I use a Linux kernel 4.9 from the yocto freescale meta. I checked the communication via oscilloscope. The "read" questions to the PHY are correct.

Greeting
Mario

0 Ross Pimentel over 5 years ago in reply to Mario Bernhard

TI__Mastermind 23675 points

Hi Mario,

Can you probe MDC and MDIO for us so that we can see the transaction?
Can you send the schematic?

0 Mario Bernhard over 5 years ago in reply to Ross Pimentel

Prodigy 80 points

Hi,

the image of the oscilloscope is without a Pull-Up. So I get the board.

I had subsequently pull on MDC and MDIO. But since I do not have the right equipment for such work to do, I removed this for safety's sake.

Best regards,

Mario

0 Geet Modi over 5 years ago in reply to Mario Bernhard

TI__Mastermind 26320 points

Hi Mario,

Your schematics does not show Pull-up on MDIO. Please add only on MDIO. MDC do not need Pull-up.

Also, you may want to measure do basic checks :
a. the XTAL is clocking correctly at 25 MHz.
b. Supply voltage are with in range.
c. Device is not in RESET : Reset is active low.

Regards,
Geet

0 Mario Bernhard over 5 years ago in reply to Geet Modi

Prodigy 80 points

Hi,

I have now only at MDIO a 2.2K Pull-up - no change.

Clock and voltage are:
X_I 25Mhz
VDDIO 1.80 V
VDD1P0 1.04 V
VDDA2P5 2.51 V
RESET_N 1.25 V

Best regards,
Mario

0 Ross Pimentel over 5 years ago in reply to Mario Bernhard

TI__Mastermind 23675 points

Hi Mario,

The device could be on the boarder of being in reset.
When the PHY has a VDDIO of 1.8V, the min VIH is 0.7*VDDIO.
This means that VIH is 1.26V.
Can you drive RESET high to 1.8V?

0 Mario Bernhard over 5 years ago in reply to Ross Pimentel

Prodigy 80 points

Hi,

I have the reset voltage raised on 1.8 V.

At the behavior of the PHY unfortunately, nothing changed.

Best regards,
Mario

0 Geet Modi over 5 years ago in reply to Mario Bernhard

TI__Mastermind 26320 points

1. How you are reading the MDIO registers ? Which tool ?
2. Which tool you are using to read ?
3. Did you try various phy id : 00 to 16 ?
4. Do you see clock on RX_CLK ?
Regards,
Geet

0 Mario Bernhard over 5 years ago in reply to Geet Modi

Prodigy 80 points

Hi,

I am using the Freescale Kernel 4.9 (yocto) because the MDIO bus is connected via their package engine.
The driver initialization reads and writes on the bus. Where can I see the always the same answer from the bus arrives.

Yes I have changed some code in the kernel and scanned the entire address area 0-31 (5-Bit)
only to ID 0 can I get an answer.

RX_CLK - the PHY is connected via SGMII - this pin is not used.

Best regards,
Mario

0 Geet Modi over 5 years ago in reply to Mario Bernhard

TI__Mastermind 26320 points

Hi,

Typically we see zero when the MDIO and MDC are connected without common ground. Can you check if you have common for Freescale and TI Phy.

Suggest you order MSP432 LP and use TI tool to confirm.

Regards,
Geet

0 Mario Bernhard over 5 years ago in reply to Geet Modi

Prodigy 80 points

Hi,

I'm not sure how i can check this in the PHY. This is equipped as a 48-pin QFN package. GND is on the bottom.

I suspect a defective board and have obtained from the manufacturer if i can get another test board.

I would like to thank for all the help.

Regards,

Mario

0 Geet Modi over 5 years ago in reply to Mario Bernhard

TI__Mastermind 26320 points

Sure. If it still doesn't, suggest use USB-MDIO tool from ti on MSP432 LaunchPad.

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DP83867CS: Always the same value when reading via MDIO